Class Client (2.23.0-rc)

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The Google Cloud Storage (GCS) Client.

This is the main class to interact with GCS. It provides member functions to invoke all the APIs in the service.

Performance

Creating an object of this type is a relatively low-cost operation. Connections to the service are created on demand. Copy-assignment and copy-construction are also relatively low-cost operations, they should be comparable to copying a few shared pointers. The first request (or any request that requires a new connection) incurs the cost of creating the connection and authenticating with the service. Note that the library may need to perform other bookkeeping operations that may impact performance. For example, access tokens need to be refreshed from time to time, and this may impact the performance of some operations.

Connection Pool

By default this class uses HTTPS to communicate with the service. Creating a new HTTPS session is relatively expensive, as it must go through the TCP/IP and SSL handshakes. To minimize this overhead the class maintains a connection pool to the service. After each request completes the connection is returned to the pool, and reused in future requests. Note that for downloads (implemented by the ReadObject() member function) the connection remains in use until the download completes. Therefore, having multiple downloads open at the same time requires multiple connections. The application can limit the maximum size of this connection pool using storage::ConnectionPoolSizeOption. If returning a connection to the pool would make the pool larger than this limit then the oldest connection in the pool is closed (recall that all connections in the pool are inactive). Note that this is the maximum size of the pool, the client library does not create connections until needed.

Note that the application may (at times) use more connections than the maximum size of the pool. For example if N downloads are in progress the library may need N connections, even if the pool size is smaller.

Two clients that compare equal share the same connection pool. Two clients created with the default constructor or with the constructor from a google::cloud::Options are never equal and do not share connection pools. Clients created via copy (or move) construction compare equal and share the connection pool.

Thread-safety

Instances of this class created via copy-construction or copy-assignment share the underlying pool of connections. Access to these copies via multiple threads is guaranteed to work. Two threads operating on the same instance of this class is not guaranteed to work.

Credentials

The default approach for creating a Client uses Google Application Default Credentials (ADCs). Note that a default-constructed client uses the ADCs:

  namespace gcs = ::google::cloud::storage;
  [](std::string const& bucket_name, std::string const& object_name) {
    auto client = gcs::Client();
    PerformSomeOperations(client, bucket_name, object_name);
  }

Finding or loading the ADCs can fail. This will result in run-time errors when making requests.

If you prefer to explicitly load the ADCs use:

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::Options;
  using ::google::cloud::UnifiedCredentialsOption;
  [](std::string const& bucket_name, std::string const& object_name) {
    auto client = gcs::Client(Options{}.set<UnifiedCredentialsOption>(
        google::cloud::MakeGoogleDefaultCredentials()));
    PerformSomeOperations(client, bucket_name, object_name);
  }

To load a service account credentials key file use:

  namespace gcs = ::google::cloud::storage;
  [](std::string const& filename, std::string const& bucket_name,
     std::string const& object_name) {
    auto is = std::ifstream(filename);
    is.exceptions(std::ios::badbit);
    auto json_string =
        std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
    auto credentials =
        google::cloud::MakeServiceAccountCredentials(json_string);
    auto client = gcs::Client(
        google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
            credentials));
    PerformSomeOperations(client, bucket_name, object_name);
  }

Other credential types are available, including:

• google::cloud::MakeInsecureCredentials() for anonymous access to public GCS buckets or objects.
• google::cloud::MakeAccessTokenCredentials() to use an access token obtained through any out-of-band mechanism.
• google::cloud::MakeImpersonateServiceAccountCredentials() to use the IAM credentials service and [impersonate a service account].
• google::cloud::MakeServiceAccountCredentials() to use a service account key file.

Error Handling

This class uses StatusOr<T> to report errors. When an operation fails to perform its work the returned StatusOr<T> contains the error details. If the ok() member function in the StatusOr<T> returns true then it contains the expected result. Please consult the StatusOr<T> documentation for more details.

namespace gcs = google::cloud::storage;
gcs::Client client = ...;
google::cloud::StatusOr<gcs::BucketMetadata> bucket_metadata =
    client.GetBucketMetadata("my-bucket");

if (!bucket_metadata) {
  std::cerr << "Error getting metadata for my-bucket: "
            << bucket_metadata.status() << "\n";
  return;
}

// Use bucket_metadata as a smart pointer here, e.g.:
std::cout << "The generation for " << bucket_metadata->name() " is "
          << bucket_metadata->generation() << "\n";

In addition, the main page contains examples using StatusOr<T> to handle errors.

Optional Request Options

Most of the member functions in this class can receive optional request options. For example, the default when reading multi-version objects is to retrieve the latest version:

auto stream = gcs.ReadObject("my-bucket", "my-object");

Some applications may want to retrieve specific versions. In this case just provide the Generation request option:

auto stream = gcs.ReadObject(
    "my-bucket", "my-object", gcs::Generation(generation));

Each function documents the types accepted as optional request options. These parameters can be specified in any order. Specifying a request option that is not applicable to a member function results in a compile-time error.

All operations support the following common request options:

• Fields: return a partial response, which includes only the desired fields.
• QuotaUser: attribute the request to this specific label for quota purposes.
• UserProject: change the request costs (if applicable) to this GCP project.
• CustomHeader: include a custom header with the request. These are typically used for testing, though they are sometimes helpful if environments where HTTPS traffic is mediated by a proxy.
• IfMatchEtag: a pre-condition, the operation succeeds only if the resource ETag matches. Typically used in OCC loops ("change X only if its Etag is still Y"). Note that GCS sometimes ignores this header, we recommend you use the GCS specific pre-conditions (e.g., IfGenerationMatch, IfMetagenerationMatch and their *NotMatch counterparts) instead.
• IfNoneMatchEtag: a pre-condition, abort the operation if the resource ETag has not changed. Typically used in caching ("return the contents of X only if the Etag is different from the last value I got, which was Y"). Note that GCS sometimes ignores this header, we recommend you use the GCS specific pre-conditions (e.g., IfGenerationMatch, IfMetagenerationMatch and their *NotMatch counterparts) instead.
• UserIp: attribute the request to this specific IP address for quota purpose. Not recommended, prefer QuotaUser instead.

Per-operation Overrides

In addition to the request options, which are passed on to the service to modify the request, you can specify options that override the local behavior of the library. For example, you can override the local retry policy:

  namespace g = ::google::cloud;
  namespace gcs = ::google::cloud::storage;
  [](std::string const& bucket_name, std::string const& object_name_1,
     std::string const& object_name_2) {
    auto client = gcs::Client();
    auto metadata = client.InsertObject(
        bucket_name, object_name_1,
        "The quick brown fox jumps over the lazy dog",
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedTimeRetryPolicy(std::chrono::minutes(5)).clone()));
    if (!metadata) throw std::move(metadata).status();

    auto is =
        client.ReadObject(bucket_name, object_name_1,
                          g::Options{}.set<gcs::RetryPolicyOption>(
                              gcs::LimitedErrorCountRetryPolicy(10).clone()));
    auto contents = std::string{std::istreambuf_iterator<char>(is.rdbuf()), {}};
    if (is.bad()) throw google::cloud::Status(is.status());

    auto os = client.WriteObject(
        bucket_name, object_name_2,
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedTimeRetryPolicy(std::chrono::minutes(5)).clone()));
    os << contents;
    os.Close();
    if (os.bad()) throw google::cloud::Status(os.metadata().status());

    auto result = client.DeleteObject(
        bucket_name, object_name_1, gcs::Generation(metadata->generation()),
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedErrorCountRetryPolicy(12).clone()));
    if (!result.ok()) throw std::move(metadata).status();

    metadata = os.metadata();
    result = client.DeleteObject(
        bucket_name, object_name_2, gcs::Generation(metadata->generation()),
        g::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedErrorCountRetryPolicy(12).clone()));
    if (!result.ok()) throw std::move(metadata).status();
  }

Retry, Backoff, and Idempotency Policies

The library automatically retries requests that fail with transient errors, and follows the recommended practice to backoff between retries.

The default policies are to continue retrying for up to 15 minutes, and to use truncated (at 5 minutes) exponential backoff, doubling the maximum backoff period between retries. Likewise, the idempotency policy is configured to retry all operations.

The application can override these policies when constructing objects of this class. The documentation for the constructors show examples of this in action.

See Also

https://cloud.google.com/storage/ for an overview of GCS.

See Also

https://cloud.google.com/storage/docs/key-terms for an introduction of the key terms used in GCS.

See Also

https://cloud.google.com/storage/docs/json_api/ for an overview of the underlying API.

See Also

https://cloud.google.com/docs/authentication/production for details about Application Default Credentials.

See Also

google::cloud::StatusOr.

See Also

LimitedTimeRetryPolicy and LimitedErrorCountRetryPolicy for alternative retry policies.

See Also

ExponentialBackoffPolicy to configure different parameters for the exponential backoff policy.

See Also

AlwaysRetryIdempotencyPolicy and StrictIdempotencyPolicy for alternative idempotency policies.

Constructors

Client(Options)

Build a new client.

See Also

ClientOptionList for a list of useful Client Library Configuration.

Idempotency Policy Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](std::string const& bucket_name, std::string const& object_name,
     std::string const& contents) {
    // Create a client that only retries idempotent operations, the default is
    // to retry all operations.
    auto client =
        gcs::Client(google::cloud::Options{}.set<gcs::IdempotencyPolicyOption>(
            gcs::StrictIdempotencyPolicy().clone()));
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents),
                            gcs::IfGenerationMatch(0));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Modified Retry Policy Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](std::string const& bucket_name, std::string const& object_name,
     std::string const& contents) {
    // Create a client that only gives up on the third error. The default policy
    // is to retry for several minutes.
    auto client =
        gcs::Client(google::cloud::Options{}.set<gcs::RetryPolicyOption>(
            gcs::LimitedErrorCountRetryPolicy(3).clone()));

    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents),
                            gcs::IfGenerationMatch(0));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Change Credentials Example

  namespace gcs = ::google::cloud::storage;
  [](std::string const& filename, std::string const& bucket_name,
     std::string const& object_name) {
    auto is = std::ifstream(filename);
    is.exceptions(std::ios::badbit);
    auto json_string =
        std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
    auto credentials =
        google::cloud::MakeServiceAccountCredentials(json_string);
    auto client = gcs::Client(
        google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
            credentials));
    PerformSomeOperations(client, bucket_name, object_name);
  }

Parameter
Name	Description
opts	Options the configuration parameters for the Client.

Client(ClientOptions, Policies &&...)

Creates the default client type given the options.

Deprecated: use the constructor from google::cloud::Options instead.

Parameters
Name	Description
options	ClientOptions the client options, these are used to control credentials, buffer sizes, etc.
policies	Policies &&... the client policies, these control the behavior of the client, for example, how to backoff when an operation needs to be retried, or what operations cannot be retried because they are not idempotent.
typename...

Client(std::shared_ptr< oauth2::Credentials >, Policies &&...)

Creates the default client type given the credentials and policies.

Deprecated: use the constructor from google::cloud::Options instead.

Parameters
Name	Description
credentials	std::shared_ptr< oauth2::Credentials > a set of credentials to initialize the ClientOptions.
policies	Policies &&... the client policies, these control the behavior of the client, for example, how to backoff when an operation needs to be retried, or what operations cannot be retried because they are not idempotent.
typename...

Client(std::shared_ptr< internal::StorageConnection > const &, Policies &&...)

Builds a client and maybe override the retry, idempotency, and/or backoff policies.

Deprecated: This was intended only for test code, applications should not use it.

Parameters
Name	Description
connection	std::shared_ptr< internal::StorageConnection > const &
policies	Policies &&...
typename...

Client(std::shared_ptr< internal::StorageConnection >, NoDecorations)

Builds a client with a specific StorageConnection, without decorations.

Deprecated: This was intended only for test code, applications should not use it.

Parameters
Name	Description
connection	std::shared_ptr< internal::StorageConnection >
	NoDecorations

Functions

ListBucketsForProject(std::string const &, Options &&...)

Fetches the list of buckets for a given project.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& project_id) {
    int count = 0;
    for (auto&& bucket_metadata : client.ListBucketsForProject(project_id)) {
      if (!bucket_metadata) throw std::move(bucket_metadata).status();

      std::cout << bucket_metadata->name() << "\n";
      ++count;
    }

    if (count == 0) {
      std::cout << "No buckets in project " << project_id << "\n";
    }
  }

Parameters
Name	Description
project_id	std::string const & the project to query.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include MaxResults, Prefix, Projection, and UserProject. OverrideDefaultProject is accepted, but has no effect.
typename...

Returns
Type	Description
ListBucketsReader

ListBuckets(Options &&...)

Fetches the list of buckets for the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

• Any parameters of type OverrideDefaultProject, with a value.
• Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
• Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
• The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client) {
    int count = 0;
    gcs::ListBucketsReader bucket_list = client.ListBuckets();
    for (auto&& bucket_metadata : bucket_list) {
      if (!bucket_metadata) throw std::move(bucket_metadata).status();

      std::cout << bucket_metadata->name() << "\n";
      ++count;
    }

    if (count == 0) {
      std::cout << "No buckets in default project\n";
    }
  }

Parameters
Name	Description
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include MaxResults, Prefix, Projection, UserProject, and OverrideDefaultProject.
typename...

Returns
Type	Description
ListBucketsReader

CreateBucket(std::string, BucketMetadata, Options &&...)

Creates a new Google Cloud Storage bucket using the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

• Any parameters of type OverrideDefaultProject, with a value.
• Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
• Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
• The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This operation is always idempotent. It fails if the bucket already exists.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.CreateBucket(bucket_name, gcs::BucketMetadata());
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    std::cout << "Bucket " << bucket_metadata->name() << " created."
              << "\nFull Metadata: " << *bucket_metadata << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access ?".

Parameters
Name	Description
bucket_name	std::string the name of the new bucket.
metadata	BucketMetadata the metadata for the new Bucket. The name field is ignored in favor of bucket_name.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include PredefinedAcl, PredefinedDefaultObjectAcl, Projection, UserProject, and OverrideDefaultProject.
typename...

Returns
Type	Description
StatusOr< BucketMetadata >

CreateBucketForProject(std::string, std::string, BucketMetadata, Options &&...)

Creates a new Google Cloud Storage Bucket in a given project.

Idempotency

This operation is always idempotent. It fails if the bucket already exists.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& project_id) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.CreateBucketForProject(bucket_name, project_id,
                                      gcs::BucketMetadata{});
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    std::cout << "Bucket " << bucket_metadata->name() << " created for project "
              << project_id << " [" << bucket_metadata->project_number() << "]"
              << "\nFull Metadata: " << *bucket_metadata << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access ?".

Parameters
Name	Description
bucket_name	std::string the name of the new bucket.
project_id	std::string the id of the project that will host the new bucket.
metadata	BucketMetadata the metadata for the new Bucket. The name field is ignored in favor of bucket_name.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include PredefinedAcl, PredefinedDefaultObjectAcl, Projection, and UserProject. OverrideDefaultProject is accepted, but has no effect.
typename...

Returns
Type	Description
StatusOr< BucketMetadata >

GetBucketMetadata(std::string const &, Options &&...)

Fetches the bucket metadata.

Idempotency

This is a read-only operation and is always idempotent.

Example

  // [START storage_get_bucket_metadata]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.GetBucketMetadata(bucket_name);
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    std::cout << "The metadata for bucket " << bucket_metadata->name() << " is "
              << *bucket_metadata << "\n";
  }
  // [END storage_get_bucket_metadata]

Parameters
Name	Description
bucket_name	std::string const & query metadata information about this bucket.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include IfMetagenerationMatch, IfMetagenerationNotMatch, UserProject, and Projection.
typename...

Returns
Type	Description
StatusOr< BucketMetadata >

DeleteBucket(std::string const &, Options &&...)

Deletes a Google Cloud Storage Bucket.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name) {
    google::cloud::Status status = client.DeleteBucket(bucket_name);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "The bucket " << bucket_name << " was deleted successfully.\n";
  }

Parameters
Name	Description
bucket_name	std::string const & the bucket to be deleted.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include IfMetagenerationMatch, IfMetagenerationNotMatch, and UserProject.
typename...

Returns
Type	Description
Status

UpdateBucket(std::string, BucketMetadata, Options &&...)

Updates the metadata in a Google Cloud Storage Bucket.

A Buckets: update request changes all the writeable attributes of a bucket, in contrast, a Buckets: patch request only changes the subset of the attributes included in the request. This function creates a Buckets: update request to change the writable attributes in BucketMetadata.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case,IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& storage_class) {
    StatusOr<gcs::BucketMetadata> meta = client.GetBucketMetadata(bucket_name);
    if (!meta) throw std::move(meta).status();

    meta->set_storage_class(storage_class);
    StatusOr<gcs::BucketMetadata> updated =
        client.UpdateBucket(bucket_name, *meta);
    if (!updated) throw std::move(updated).status();

    std::cout << "Updated the storage class in " << updated->name() << " to "
              << updated->storage_class() << "."
              << "\nFull metadata:" << *updated << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access ?".

Parameters
Name	Description
bucket_name	std::string the name of the new bucket.
metadata	BucketMetadata the new metadata for the Bucket. The name field is ignored in favor of bucket_name.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include IfMetagenerationMatch, IfMetagenerationNotMatch, PredefinedAcl, PredefinedDefaultObjectAcl, Projection, and UserProject.
typename...

Returns
Type	Description
StatusOr< BucketMetadata >

PatchBucket(std::string, BucketMetadata const &, BucketMetadata const &, Options &&...)

Computes the difference between two BucketMetadata objects and patches a bucket based on that difference.

A Buckets: update request changes all the writeable attributes of a bucket, in contrast, a Buckets: patch request only changes the subset of the attributes included in the request.

This function creates a patch request to change the writeable attributes in original to the values in updated. Non-writeable attributes are ignored, and attributes not present in updated are removed. Typically this function is used after the application obtained a value with GetBucketMetadata and has modified these parameters.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& storage_class) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    gcs::BucketMetadata desired = *original;
    desired.set_storage_class(storage_class);

    StatusOr<gcs::BucketMetadata> patched =
        client.PatchBucket(bucket_name, *original, desired);
    if (!patched) throw std::move(patched).status();

    std::cout << "Storage class for bucket " << patched->name()
              << " has been patched to " << patched->storage_class() << "."
              << "\nFull metadata: " << *patched << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access?".

Parameters
Name	Description
bucket_name	std::string the bucket to be updated.
original	BucketMetadata const & the initial value of the bucket metadata.
updated	BucketMetadata const & the updated value for the bucket metadata.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include IfMetagenerationMatch, IfMetagenerationNotMatch, PredefinedAcl, PredefinedDefaultObjectAcl, Projection, and UserProject.
typename...

Returns
Type	Description
StatusOr< BucketMetadata >

PatchBucket(std::string, BucketMetadataPatchBuilder const &, Options &&...)

Patches the metadata in a Google Cloud Storage Bucket given a desired set changes.

A Buckets: update request changes all the writeable attributes of a bucket, in contrast, a Buckets: patch request only changes the subset of the attributes included in the request. This function creates a patch request based on the given BucketMetadataPatchBuilder which represents the desired set of changes.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& storage_class) {
    StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
        bucket_name,
        gcs::BucketMetadataPatchBuilder().SetStorageClass(storage_class));
    if (!patched) throw std::move(patched).status();

    std::cout << "Storage class for bucket " << patched->name()
              << " has been patched to " << patched->storage_class() << "."
              << "\nFull metadata: " << *patched << "\n";
  }

See Also

Before enabling Uniform Bucket Level Access please review the feature documentation, as well as "Should you use uniform bucket-level access ?".

Parameters
Name	Description
bucket_name	std::string the bucket to be updated.
builder	BucketMetadataPatchBuilder const & the set of updates to perform in the Bucket.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include IfMetagenerationMatch, IfMetagenerationNotMatch, PredefinedAcl, PredefinedDefaultObjectAcl, Projection, and UserProject.
typename...

Returns
Type	Description
StatusOr< BucketMetadata >

GetNativeBucketIamPolicy(std::string const &, Options &&...)

Fetches the native IAM policy for a Bucket.

Google Cloud Identity & Access Management (IAM) lets administrators authorize who can take action on specific resources, including Google Cloud Storage Buckets. This operation allows you to query the IAM policies for a Bucket. IAM policies are a superset of the Bucket ACL, changes to the Bucket ACL are reflected in the IAM policy, and vice-versa. The documentation describes the mapping between legacy Bucket ACLs and IAM policies.

Consult the documentation for a more detailed description of IAM policies and their use in Google Cloud Storage.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    auto policy = client.GetNativeBucketIamPolicy(
        bucket_name, gcs::RequestedPolicyVersion(3));

    if (!policy) throw std::move(policy).status();
    std::cout << "The IAM policy for bucket " << bucket_name << " is "
              << *policy << "\n";
  }

See Also

google::cloud::storage::NativeIamPolicy for details about the NativeIamPolicy class.

Parameters
Name	Description
bucket_name	std::string const & query metadata information about this bucket.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< NativeIamPolicy >

SetNativeBucketIamPolicy(std::string const &, NativeIamPolicy const &, Options &&...)

Sets the native IAM Policy for a Bucket.

Google Cloud Identity & Access Management (IAM) lets administrators authorize who can take action on specific resources, including Google Cloud Storage Buckets. This operation allows you to set the IAM policies for a Bucket. IAM policies are a superset of the Bucket ACL, changes to the Bucket ACL are reflected in the IAM policy, and vice-versa. The documentation describes the mapping between legacy Bucket ACLs and IAM policies.

Consult the documentation for a more detailed description of IAM policies their use in Google Cloud Storage.

Note: The server rejects requests where the ETag value of the policy does not match the current ETag. Effectively this means that applications must use GetNativeBucketIamPolicy() to fetch the current value and ETag before calling SetNativeBucketIamPolicy(). Applications should use optimistic concurrency control techniques to retry changes in case some other application modified the IAM policy between the GetNativeBucketIamPolicy and SetNativeBucketIamPolicy calls.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example: adding a new member

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& role, std::string const& member) {
    auto policy = client.GetNativeBucketIamPolicy(
        bucket_name, gcs::RequestedPolicyVersion(3));

    if (!policy) throw std::move(policy).status();

    policy->set_version(3);
    for (auto& binding : policy->bindings()) {
      if (binding.role() != role || binding.has_condition()) {
        continue;
      }
      auto& members = binding.members();
      if (std::find(members.begin(), members.end(), member) == members.end()) {
        members.emplace_back(member);
      }
    }

    auto updated = client.SetNativeBucketIamPolicy(bucket_name, *policy);
    if (!updated) throw std::move(updated).status();

    std::cout << "Updated IAM policy bucket " << bucket_name
              << ". The new policy is " << *updated << "\n";
  }

Example: removing a IAM member

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& role, std::string const& member) {
    auto policy = client.GetNativeBucketIamPolicy(
        bucket_name, gcs::RequestedPolicyVersion(3));
    if (!policy) throw std::move(policy).status();

    policy->set_version(3);
    std::vector<google::cloud::storage::NativeIamBinding> updated_bindings;
    for (auto& binding : policy->bindings()) {
      auto& members = binding.members();
      if (binding.role() == role && !binding.has_condition()) {
        members.erase(std::remove(members.begin(), members.end(), member),
                      members.end());
      }
      if (!members.empty()) {
        updated_bindings.emplace_back(std::move(binding));
      }
    }
    policy->bindings() = std::move(updated_bindings);

    auto updated = client.SetNativeBucketIamPolicy(bucket_name, *policy);
    if (!updated) throw std::move(updated).status();

    std::cout << "Updated IAM policy bucket " << bucket_name
              << ". The new policy is " << *updated << "\n";
  }

See Also

google::cloud::storage::NativeIamPolicy for details about the NativeIamPolicy class.

Parameters
Name	Description
bucket_name	std::string const & query metadata information about this bucket.
iam_policy	NativeIamPolicy const & the new IAM policy.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< NativeIamPolicy >

TestBucketIamPermissions(std::string, std::vector< std::string >, Options &&...)

Tests the IAM permissions of the caller against a Bucket.

Google Cloud Identity & Access Management (IAM) lets administrators authorize who can take action on specific resources, including Google Cloud Storage Buckets. This operation tests the permissions of the caller for a Bucket. You must provide a list of permissions, this API will return the subset of those permissions that the current caller has in the given Bucket.

Consult the documentation for a more detailed description of IAM policies their use in Google Cloud Storage.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::vector<std::string> const& permissions) {
    StatusOr<std::vector<std::string>> actual_permissions =
        client.TestBucketIamPermissions(bucket_name, permissions);
    if (!actual_permissions) throw std::move(actual_permissions).status();

    if (actual_permissions->empty()) {
      std::cout << "The caller does not hold any of the tested permissions the"
                << " bucket " << bucket_name << "\n";
      return;
    }

    std::cout << "The caller is authorized for the following permissions on "
              << bucket_name << ": ";
    for (auto const& permission : *actual_permissions) {
      std::cout << "\n    " << permission;
    }
    std::cout << "\n";
  }

Parameters
Name	Description
bucket_name	std::string query metadata information about this bucket.
permissions	std::vector< std::string > the list of permissions to check.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< std::vector< std::string > >

LockBucketRetentionPolicy(std::string const &, std::uint64_t, Options &&...)

Locks the retention policy for a bucket.

Warning: Locking a retention policy is an irreversible action. Once locked, you must delete the entire bucket in order to "remove" the bucket's retention policy. However, before you can delete the bucket, you must be able to delete all the objects in the bucket, which itself is only possible if all the objects have reached the retention period set by the retention policy.

The Bucket Lock feature allows you to configure a data retention policy for a Cloud Storage bucket that governs how long objects in the bucket must be retained. The feature also allows you to lock the data retention policy, permanently preventing the policy from being reduced or removed.

Idempotency

This operation is always idempotent because the metageneration parameter is always required, and it acts as a pre-condition on the operation.

Example: lock the retention policy

  // [START storage_lock_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    StatusOr<gcs::BucketMetadata> updated_metadata =
        client.LockBucketRetentionPolicy(bucket_name,
                                         original->metageneration());
    if (!updated_metadata) throw std::move(updated_metadata).status();

    if (!updated_metadata->has_retention_policy()) {
      std::cerr << "The bucket " << updated_metadata->name()
                << " does not have a retention policy, even though the"
                << " operation to set it was successful.\n"
                << "This is unexpected, and may indicate that another"
                << " application has modified the bucket concurrently.\n";
      return;
    }

    std::cout << "Retention policy successfully locked for bucket "
              << updated_metadata->name() << "\nNew retention policy is: "
              << updated_metadata->retention_policy()
              << "\nFull metadata: " << *updated_metadata << "\n";
  }
  // [END storage_lock_retention_policy]

Example: get the current retention policy

  // [START storage_get_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> bucket_metadata =
        client.GetBucketMetadata(bucket_name);
    if (!bucket_metadata) throw std::move(bucket_metadata).status();

    if (!bucket_metadata->has_retention_policy()) {
      std::cout << "The bucket " << bucket_metadata->name()
                << " does not have a retention policy set.\n";
      return;
    }

    std::cout << "The bucket " << bucket_metadata->name()
              << " retention policy is set to "
              << bucket_metadata->retention_policy() << "\n";
  }
  // [END storage_get_retention_policy]

Example: set the current retention policy

  // [START storage_set_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::chrono::seconds period) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
        bucket_name,
        gcs::BucketMetadataPatchBuilder().SetRetentionPolicy(period),
        gcs::IfMetagenerationMatch(original->metageneration()));
    if (!patched) throw std::move(patched).status();

    if (!patched->has_retention_policy()) {
      std::cout << "The bucket " << patched->name()
                << " does not have a retention policy set.\n";
      return;
    }

    std::cout << "The bucket " << patched->name()
              << " retention policy is set to " << patched->retention_policy()
              << "\n";
  }
  // [END storage_set_retention_policy]

Example: remove the retention policy

  // [START storage_remove_retention_policy]
  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<gcs::BucketMetadata> original =
        client.GetBucketMetadata(bucket_name);
    if (!original) throw std::move(original).status();

    StatusOr<gcs::BucketMetadata> patched = client.PatchBucket(
        bucket_name, gcs::BucketMetadataPatchBuilder().ResetRetentionPolicy(),
        gcs::IfMetagenerationMatch(original->metageneration()));
    if (!patched) throw std::move(patched).status();

    if (!patched->has_retention_policy()) {
      std::cout << "The bucket " << patched->name()
                << " does not have a retention policy set.\n";
      return;
    }

    std::cout << "The bucket " << patched->name()
              << " retention policy is set to " << patched->retention_policy()
              << ". This is unexpected, maybe a concurrent change by another"
              << " application?\n";
  }
  // [END storage_remove_retention_policy]

See Also

https://cloud.google.com/storage/docs/bucket-lock for a description of the Bucket Lock feature.

See Also

https://cloud.google.com/storage/docs/using-bucket-lock for examples of how to use the Bucket Lock and retention policy features.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
metageneration	std::uint64_t the expected value of the metageneration on the bucket. The request will fail if the metageneration does not match the current value.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< BucketMetadata >

InsertObject(std::string const &, std::string const &, absl::string_view, Options &&...)

Creates an object given its name and contents.

If you need to perform larger uploads or uploads where the data is not contiguous in memory, use WriteObject(). This function always performs a single-shot upload, while WriteObject() always uses resumable uploads. The service documentation has recommendations on the upload size vs. single-shot or resumable uploads.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& contents) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type,
     std::string const& contents) {
    // Setting the object metadata (via the `gcs::WithObjectMadata` option)
    // requires a multipart upload, the library prefers simple uploads unless
    // required as in this case.
    StatusOr<gcs::ObjectMetadata> object_metadata = client.InsertObject(
        bucket_name, object_name, std::move(contents),
        gcs::WithObjectMetadata(
            gcs::ObjectMetadata().set_content_type(content_type)));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nThe contentType was set to "
              << object_metadata->content_type()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that will contain the object.
object_name	std::string const & the name of the object to be created.
contents	absl::string_view the contents (media) for the new object.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include ContentEncoding, ContentType, Crc32cChecksumValue, DisableCrc32cChecksum, DisableMD5Hash, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, KmsKeyName, MD5HashValue, PredefinedAcl, Projection, UserProject, and WithObjectMetadata.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

InsertObject(std::string const &, std::string const &, std::string const &, Options &&...)

Creates an object given its name and contents.

If you need to perform larger uploads or uploads where the data is not contiguous in memory, use WriteObject(). This function always performs a single-shot upload, while WriteObject() always uses resumable uploads. The service documentation has recommendations on the upload size vs. single-shot or resumable uploads.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& contents) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type,
     std::string const& contents) {
    // Setting the object metadata (via the `gcs::WithObjectMadata` option)
    // requires a multipart upload, the library prefers simple uploads unless
    // required as in this case.
    StatusOr<gcs::ObjectMetadata> object_metadata = client.InsertObject(
        bucket_name, object_name, std::move(contents),
        gcs::WithObjectMetadata(
            gcs::ObjectMetadata().set_content_type(content_type)));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nThe contentType was set to "
              << object_metadata->content_type()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that will contain the object.
object_name	std::string const & the name of the object to be created.
contents	std::string const & the contents (media) for the new object.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include ContentEncoding, ContentType, Crc32cChecksumValue, DisableCrc32cChecksum, DisableMD5Hash, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, KmsKeyName, MD5HashValue, PredefinedAcl, Projection, UserProject, and WithObjectMetadata.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

InsertObject(std::string const &, std::string const &, char const *, Options &&...)

Creates an object given its name and contents.

If you need to perform larger uploads or uploads where the data is not contiguous in memory, use WriteObject(). This function always performs a single-shot upload, while WriteObject() always uses resumable uploads. The service documentation has recommendations on the upload size vs. single-shot or resumable uploads.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& contents) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.InsertObject(bucket_name, object_name, std::move(contents));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type,
     std::string const& contents) {
    // Setting the object metadata (via the `gcs::WithObjectMadata` option)
    // requires a multipart upload, the library prefers simple uploads unless
    // required as in this case.
    StatusOr<gcs::ObjectMetadata> object_metadata = client.InsertObject(
        bucket_name, object_name, std::move(contents),
        gcs::WithObjectMetadata(
            gcs::ObjectMetadata().set_content_type(content_type)));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The object " << object_metadata->name()
              << " was created in bucket " << object_metadata->bucket()
              << "\nThe contentType was set to "
              << object_metadata->content_type()
              << "\nFull metadata: " << *object_metadata << "\n";
  }

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that will contain the object.
object_name	std::string const & the name of the object to be created.
contents	char const * the contents (media) for the new object.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include ContentEncoding, ContentType, Crc32cChecksumValue, DisableCrc32cChecksum, DisableMD5Hash, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, KmsKeyName, MD5HashValue, PredefinedAcl, Projection, UserProject, and WithObjectMetadata.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

CopyObject(std::string, std::string, std::string, std::string, Options &&...)

Copies an existing object.

Use CopyObject to copy between objects in the same location and storage class. Copying objects across locations or storage classes can fail for large objects and retrying the operation will not succeed.

Note: Prefer using RewriteObject() to copy objects, RewriteObject() can copy objects to different locations, with different storage class, and/or with different encryption keys.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name) {
    StatusOr<gcs::ObjectMetadata> new_copy_meta =
        client.CopyObject(source_bucket_name, source_object_name,
                          destination_bucket_name, destination_object_name);
    if (!new_copy_meta) throw std::move(new_copy_meta).status();

    std::cout << "Successfully copied " << source_object_name << " in bucket "
              << source_bucket_name << " to bucket " << new_copy_meta->bucket()
              << " with name " << new_copy_meta->name()
              << ".\nThe full metadata after the copy is: " << *new_copy_meta
              << "\n";
  }

Example: copy an encrypted object

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name,
     std::string const& key_base64) {
    StatusOr<gcs::ObjectMetadata> new_copy_meta = client.CopyObject(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name, gcs::EncryptionKey::FromBase64Key(key_base64));
    if (!new_copy_meta) throw std::move(new_copy_meta).status();

    std::cout << "Successfully copied " << source_object_name << " in bucket "
              << source_bucket_name << " to bucket " << new_copy_meta->bucket()
              << " with name " << new_copy_meta->name()
              << ".\nThe full metadata after the copy is: " << *new_copy_meta
              << "\n";
  }

See Also

https://cloud.google.com/storage/docs/json_api/v1/objects/copy for a full description of the advantages of Objects: rewrite over Objects: copy.

Parameters
Name	Description
source_bucket_name	std::string the name of the bucket that contains the object to be copied.
source_object_name	std::string the name of the object to copy.
destination_bucket_name	std::string the name of the bucket that will contain the new object.
destination_object_name	std::string the name of the new object.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include DestinationKmsKeyName, DestinationPredefinedAcl,EncryptionKey,IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, IfSourceGenerationMatch, IfSourceGenerationNotMatch, IfSourceMetagenerationMatch, IfSourceMetagenerationNotMatch, Projection, SourceGeneration, SourceEncryptionKey, UserProject, and WithObjectMetadata.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

GetObjectMetadata(std::string const &, std::string const &, Options &&...)

Fetches the object metadata.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.GetObjectMetadata(bucket_name, object_name);
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "The metadata for object " << object_metadata->name()
              << " in bucket " << object_metadata->bucket() << " is "
              << *object_metadata << "\n";
  }

Parameters
Name	Description
bucket_name	std::string const & the bucket containing the object.
object_name	std::string const & the object name.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, SoftDeleted, Projection, and UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

ListObjects(std::string const &, Options &&...)

Lists the objects in a bucket.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name) {
    for (auto&& object_metadata : client.ListObjects(bucket_name)) {
      if (!object_metadata) throw std::move(object_metadata).status();

      std::cout << "bucket_name=" << object_metadata->bucket()
                << ", object_name=" << object_metadata->name() << "\n";
    }
  }

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket to list.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include MaxResults, Prefix, Delimiter, IncludeTrailingDelimiter, StartOffset, EndOffset, MatchGlob, Projection, SoftDeleted, UserProject, and Versions.
typename...

Returns
Type	Description
ListObjectsReader

ListObjectsAndPrefixes(std::string const &, Options &&...)

Lists the objects and prefixes in a bucket.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& bucket_prefix) {
    for (auto&& item : client.ListObjectsAndPrefixes(
             bucket_name, gcs::Prefix(bucket_prefix), gcs::Delimiter("/"))) {
      if (!item) throw std::move(item).status();
      auto result = *std::move(item);
      if (absl::holds_alternative<gcs::ObjectMetadata>(result)) {
        std::cout << "object_name="
                  << absl::get<gcs::ObjectMetadata>(result).name() << "\n";
      } else if (absl::holds_alternative<std::string>(result)) {
        std::cout << "prefix     =" << absl::get<std::string>(result) << "\n";
      }
    }
  }

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& bucket_prefix) {
    for (auto&& item : client.ListObjectsAndPrefixes(
             bucket_name, gcs::Prefix(bucket_prefix), gcs::Delimiter("/"),
             gcs::IncludeFoldersAsPrefixes(true))) {
      if (!item) throw std::move(item).status();
      auto result = *std::move(item);
      if (absl::holds_alternative<gcs::ObjectMetadata>(result)) {
        std::cout << "object_name="
                  << absl::get<gcs::ObjectMetadata>(result).name() << "\n";
      } else if (absl::holds_alternative<std::string>(result)) {
        std::cout << "prefix     =" << absl::get<std::string>(result) << "\n";
      }
    }
  }

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket to list.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include IfMetagenerationMatch, IfMetagenerationNotMatch, UserProject, Projection, Prefix, Delimiter, IncludeTrailingDelimiter, IncludeFoldersAsPrefixes, StartOffset, EndOffset, MatchGlob, SoftDeleted, and Versions.
typename...

Returns
Type	Description
ListObjectsAndPrefixesReader

ReadObject(std::string const &, std::string const &, Options &&...)

Reads the contents of an object.

Returns an object derived from std::istream which can be used to read the contents of the GCS blob. The application should check the badbit (e.g. by calling stream.bad()) on the returned object to detect if there was an error reading from the blob. If badbit is set, the application can check the status() variable to get details about the failure. Applications can also set the exception mask on the returned stream, in which case an exception is thrown if an error is detected.

Idempotency

This is a read-only operation and is always idempotent.

Example

  // [START storage_stream_file_download]
  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    gcs::ObjectReadStream stream = client.ReadObject(bucket_name, object_name);

    int count = 0;
    std::string line;
    while (std::getline(stream, line, '\n')) {
      ++count;
    }
    if (stream.bad()) throw google::cloud::Status(stream.status());

    std::cout << "The object has " << count << " lines\n";
  }
  // [END storage_stream_file_download]

Example: read only a sub-range in the object.

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::int64_t start, std::int64_t end) {
    gcs::ObjectReadStream stream =
        client.ReadObject(bucket_name, object_name, gcs::ReadRange(start, end));

    int count = 0;
    std::string line;
    while (std::getline(stream, line, '\n')) {
      std::cout << line << "\n";
      ++count;
    }
    if (stream.bad()) throw google::cloud::Status(stream.status());

    std::cout << "The requested range has " << count << " lines\n";
  }

Example: read a object encrypted with a CSEK.

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& base64_aes256_key) {
    gcs::ObjectReadStream stream =
        client.ReadObject(bucket_name, object_name,
                          gcs::EncryptionKey::FromBase64Key(base64_aes256_key));

    std::string data(std::istreambuf_iterator<char>{stream}, {});
    if (stream.bad()) throw google::cloud::Status(stream.status());
    std::cout << "The object contents are: " << data << "\n";
  }

Example: disable decompressive transcoding.

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    auto is =
        client.ReadObject(bucket_name, object_name, gcs::AcceptEncodingGzip());
    auto const contents = std::string{std::istream_iterator<char>(is), {}};
    if (is.bad()) throw google::cloud::Status(is.status());
    std::cout << "The object has " << contents.size() << " characters\n";
  }

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object to be read.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include DisableCrc32cChecksum, DisableMD5Hash, EncryptionKey, Generation, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, ReadFromOffset, ReadRange, ReadLast, UserProject, and AcceptEncoding.
typename...

Returns
Type	Description
ObjectReadStream

WriteObject(std::string const &, std::string const &, Options &&...)

Writes contents into an object.

This creates a std::ostream object to upload contents. The application can use either the regular operator<<(), or std::ostream::write() to upload data.

For small uploads where all the data is contiguous in memory we recommend using InsertObject(). The service documentation has specific recommendations on object sizes and upload types.

This function always uses resumable uploads. The application can provide a #RestoreResumableUploadSession() option to resume a previously created upload. The returned object has accessors to query the session id and the next byte expected by GCS.

Note: When resuming uploads it is the application's responsibility to save the session id to restart the upload later. Likewise, it is the application's responsibility to query the next expected byte and send the remaining data without gaps or duplications.

If the application does not provide a #RestoreResumableUploadSession() option, or it provides the #NewResumableUploadSession() option then a new resumable upload session is created.

More information about buffering and recommendations around performance in the ObjectWriteStream class documentation.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, int desired_line_count) {
    std::string const text = "Lorem ipsum dolor sit amet";
    gcs::ObjectWriteStream stream =
        client.WriteObject(bucket_name, object_name);

    for (int lineno = 0; lineno != desired_line_count; ++lineno) {
      // Add 1 to the counter, because it is conventional to number lines
      // starting at 1.
      stream << (lineno + 1) << ": " << text << "\n";
    }

    stream.Close();

    StatusOr<gcs::ObjectMetadata> metadata = std::move(stream).metadata();
    if (!metadata) throw std::move(metadata).status();
    std::cout << "Successfully wrote to object " << metadata->name()
              << " its size is: " << metadata->size()
              << "\nFull metadata: " << *metadata << "\n";
  }

Example: write an object with a CMEK.

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& kms_key_name) {
    gcs::ObjectWriteStream stream = client.WriteObject(
        bucket_name, object_name, gcs::KmsKeyName(kms_key_name));

    // Line numbers start at 1.
    for (int lineno = 1; lineno <= 10; ++lineno) {
      stream << lineno << ": placeholder text for CMEK example.\n";
    }

    stream.Close();

    StatusOr<gcs::ObjectMetadata> metadata = std::move(stream).metadata();
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Successfully wrote to object " << metadata->name()
              << " its size is: " << metadata->size()
              << "\nFull metadata: " << *metadata << "\n";
  }

Example: starting a resumable upload.

  namespace gcs = ::google::cloud::storage;
  return [](gcs::Client client, std::string const& bucket_name,
            std::string const& object_name) {
    gcs::ObjectWriteStream stream = client.WriteObject(
        bucket_name, object_name, gcs::NewResumableUploadSession(),
        gcs::AutoFinalizeDisabled());
    auto session_id = stream.resumable_session_id();
    std::cout << "Created resumable upload: " << session_id << "\n";
    // Because this stream was created with `AutoFinalizeDisabled()` its
    // destructor will *not* finalize the upload, allowing a separate process or
    // function to resume and continue the upload.
    stream << "This data will not get uploaded, it is too small\n";
    return session_id;
  }

Example: resuming a resumable upload.

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& session_id) {
    // Restore a resumable upload stream, the library automatically queries the
    // state of the upload and discovers the next expected byte.
    gcs::ObjectWriteStream stream =
        client.WriteObject(bucket_name, object_name,
                           gcs::RestoreResumableUploadSession(session_id));
    if (!stream.IsOpen() && stream.metadata().ok()) {
      std::cout << "The upload has already been finalized.  The object "
                << "metadata is: " << *stream.metadata() << "\n";
    }
    if (stream.next_expected_byte() == 0) {
      // In this example we create a small object, smaller than the resumable
      // upload quantum (256 KiB), so either all the data is there or not.
      // Applications use `next_expected_byte()` to find the position in their
      // input where they need to start uploading.
      stream << R"""(
Lorem ipsum dolor sit amet, consectetur adipiscing
elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim
ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea
commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit
esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat
non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
)""";
    }

    stream.Close();

    StatusOr<gcs::ObjectMetadata> metadata = stream.metadata();
    if (!metadata) throw std::move(metadata).status();
    std::cout << "Upload completed, the new object metadata is: " << *metadata
              << "\n";
  }

See Also

Resumable Uploads for more information about resumable uploads.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object to be read.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include ContentEncoding, ContentType, Crc32cChecksumValue, DisableCrc32cChecksum, DisableMD5Hash, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, KmsKeyName, MD5HashValue, PredefinedAcl, Projection, UseResumableUploadSession, UserProject, WithObjectMetadata, UploadContentLength, AutoFinalize, and UploadBufferSize.
typename...

Returns
Type	Description
ObjectWriteStream

UploadFile(std::string const &, std::string const &, std::string const &, Options &&...)

Uploads a file to an object.

Note: Only regular files are supported. If you need to upload the results of reading a device, Named Pipe, FIFO, or other type of file system object that is not a regular file then WriteObject() is probably a better alternative.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& file_name,
     std::string const& bucket_name, std::string const& object_name) {
    // Note that the client library automatically computes a hash on the
    // client-side to verify data integrity during transmission.
    StatusOr<gcs::ObjectMetadata> metadata = client.UploadFile(
        file_name, bucket_name, object_name, gcs::IfGenerationMatch(0));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Uploaded " << file_name << " to object " << metadata->name()
              << " in bucket " << metadata->bucket()
              << "\nFull metadata: " << *metadata << "\n";
  }

Example: manually selecting a resumable upload

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& file_name,
     std::string const& bucket_name, std::string const& object_name) {
    // Note that the client library automatically computes a hash on the
    // client-side to verify data integrity during transmission.
    StatusOr<gcs::ObjectMetadata> metadata = client.UploadFile(
        file_name, bucket_name, object_name, gcs::IfGenerationMatch(0),
        gcs::NewResumableUploadSession());
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Uploaded " << file_name << " to object " << metadata->name()
              << " in bucket " << metadata->bucket()
              << "\nFull metadata: " << *metadata << "\n";
  }

Parameters
Name	Description
file_name	std::string const & the name of the file to be uploaded.
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object to be read.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include ContentEncoding, ContentType, Crc32cChecksumValue, DisableCrc32cChecksum, DisableMD5Hash, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, KmsKeyName, MD5HashValue, PredefinedAcl, Projection, UserProject, UploadFromOffset, UploadLimit and WithObjectMetadata.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

DeleteResumableUpload(std::string const &, Options &&...)

Cancel a resumable upload.

Idempotency

This operation is always idempotent because it only acts on a specific upload_session_url.

Parameters
Name	Description
upload_session_url	std::string const & the url of the upload session. Returned by ObjectWriteStream::resumable_session_id.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
Status

DownloadToFile(std::string const &, std::string const &, std::string const &, Options &&...)

Downloads a Cloud Storage object to a file.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& file_name) {
    google::cloud::Status status =
        client.DownloadToFile(bucket_name, object_name, file_name);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "Downloaded " << object_name << " to " << file_name << "\n";
  }

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object to be downloaded.
file_name	std::string const & the name of the destination file that will have the object media.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, Generation, ReadFromOffset, ReadRange, and UserProject.
typename...

Returns
Type	Description
Status

DeleteObject(std::string const &, std::string const &, Options &&...)

Deletes an object.

Idempotency

This operation is only idempotent if:

• restricted by pre-conditions, in this case, IfGenerationMatch
• or, if it applies to only one object version via Generation.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    google::cloud::Status status =
        client.DeleteObject(bucket_name, object_name);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted " << object_name << " in bucket " << bucket_name
              << "\n";
  }

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object to be deleted.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, and UserProject.
typename...

Returns
Type	Description
Status

UpdateObject(std::string, std::string, ObjectMetadata, Options &&...)

Updates the metadata in a Google Cloud Storage Object.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& key,
     std::string const& value) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.GetObjectMetadata(bucket_name, object_name);
    if (!object_metadata) throw std::move(object_metadata).status();

    gcs::ObjectMetadata desired = *object_metadata;
    desired.mutable_metadata().emplace(key, value);

    StatusOr<gcs::ObjectMetadata> updated =
        client.UpdateObject(bucket_name, object_name, desired,
                            gcs::Generation(object_metadata->generation()));

    if (!updated) throw std::move(updated).status();
    std::cout << "Object updated. The full metadata after the update is: "
              << *updated << "\n";
  }

Parameters
Name	Description
bucket_name	std::string the name of the bucket that contains the object.
object_name	std::string the name of the object.
metadata	ObjectMetadata the new metadata for the Object. Only the writeable fields accepted by the Objects: update API are used, all other fields are ignored. In particular, note that bucket and name are ignored in favor of bucket_name and object_name.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, PredefinedAcl, Projection, and UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

PatchObject(std::string, std::string, ObjectMetadata const &, ObjectMetadata const &, Options &&...)

Patches the metadata in a Google Cloud Storage Object.

This function creates a patch request to change the writeable attributes in original to the values in updated. Non-writeable attributes are ignored, and attributes not present in updated are removed. Typically this function is used after the application obtained a value with GetObjectMetadata and has modified these parameters.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& key) {
    StatusOr<gcs::ObjectMetadata> original =
        client.GetObjectMetadata(bucket_name, object_name);

    if (!original) throw std::move(original).status();
    gcs::ObjectMetadata desired = *original;
    desired.mutable_metadata().erase(key);

    StatusOr<gcs::ObjectMetadata> updated =
        client.PatchObject(bucket_name, object_name, *original, desired);

    if (!updated) throw std::move(updated).status();
    std::cout << "Object updated. The full metadata after the update is: "
              << *updated << "\n";
  }

Parameters
Name	Description
bucket_name	std::string the bucket that contains the object to be updated.
object_name	std::string the object to be updated.
original	ObjectMetadata const & the initial value of the object metadata.
updated	ObjectMetadata const & the updated value for the object metadata.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, PredefinedAcl, Projection, and UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

PatchObject(std::string, std::string, ObjectMetadataPatchBuilder const &, Options &&...)

Patches the metadata in a Google Cloud Storage Object.

This function creates a patch request based on the given builder. Typically this function is used when the application needs to set an object's metadata fields regardless of their previous value (i.e. when calling GetObjectMetadata first is not necessary).

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfMetagenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& content_type) {
    StatusOr<gcs::ObjectMetadata> updated = client.PatchObject(
        bucket_name, object_name,
        gcs::ObjectMetadataPatchBuilder().SetContentType(content_type));

    if (!updated) throw std::move(updated).status();
    std::cout << "Object updated. The full metadata after the update is: "
              << *updated << "\n";
  }

Parameters
Name	Description
bucket_name	std::string the bucket that contains the object to be updated.
object_name	std::string the object to be updated.
builder	ObjectMetadataPatchBuilder const & the set of updates to perform in the Object metadata.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfMetagenerationNotMatch, PredefinedAcl, EncryptionKey, Projection, and UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

ComposeObject(std::string, std::vector< ComposeSourceObject >, std::string, Options &&...)

Composes existing objects into a new object in the same bucket.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& destination_object_name,
     std::vector<gcs::ComposeSourceObject> const& compose_objects) {
    StatusOr<gcs::ObjectMetadata> composed_object = client.ComposeObject(
        bucket_name, compose_objects, destination_object_name);
    if (!composed_object) throw std::move(composed_object).status();

    std::cout << "Composed new object " << composed_object->name()
              << " in bucket " << composed_object->bucket()
              << "\nFull metadata: " << *composed_object << "\n";
  }

Example: using encrypted objects with CSEK

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& destination_object_name,
     std::string const& base64_aes256_key,
     std::vector<gcs::ComposeSourceObject> const& compose_objects) {
    StatusOr<gcs::ObjectMetadata> composed_object = client.ComposeObject(
        bucket_name, compose_objects, destination_object_name,
        gcs::EncryptionKey::FromBase64Key(base64_aes256_key));
    if (!composed_object) throw std::move(composed_object).status();

    std::cout << "Composed new object " << composed_object->name()
              << " in bucket " << composed_object->bucket()
              << "\nFull metadata: " << *composed_object << "\n";
  }

Parameters
Name	Description
bucket_name	std::string the name of the bucket used for source object and destination object.
source_objects	std::vector< ComposeSourceObject > objects used to compose destination_object_name.
destination_object_name	std::string the composed object name.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include DestinationPredefinedAcl, EncryptionKey, IfGenerationMatch, IfMetagenerationMatch, KmsKeyName, UserProject, and WithObjectMetadata.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >

RewriteObject(std::string, std::string, std::string, std::string, Options &&...)

Creates an ObjectRewriter to copy the source object.

Applications use this function to reliably copy objects across location boundaries, and to rewrite objects with different encryption keys. The operation returns a ObjectRewriter, which the application can use to initiate the copy and to iterate if the copy requires more than one call to complete.

Note: Application developers should be aware that rewriting large objects may take multiple hours. Multiple calls to ObjectRewriter::Iterate() may be required to completely rewrite an object.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name) {
    gcs::ObjectRewriter rewriter =
        client.RewriteObject(source_bucket_name, source_object_name,
                             destination_bucket_name, destination_object_name);

    auto callback = [](StatusOr<gcs::RewriteProgress> progress) {
      if (!progress) throw std::move(progress).status();
      std::cout << "Rewrote " << progress->total_bytes_rewritten << "/"
                << progress->object_size << "\n";
    };
    StatusOr<gcs::ObjectMetadata> metadata =
        rewriter.ResultWithProgressCallback(std::move(callback));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << metadata->name() << " in bucket "
              << metadata->bucket() << "\nFull Metadata: " << *metadata << "\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name,
     std::string const& rewrite_token) {
    gcs::ObjectRewriter rewriter = client.ResumeRewriteObject(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name, rewrite_token,
        gcs::MaxBytesRewrittenPerCall(1024 * 1024));

    auto callback = [](StatusOr<gcs::RewriteProgress> progress) {
      if (!progress) throw std::move(progress).status();
      std::cout << "Rewrote " << progress->total_bytes_rewritten << "/"
                << progress->object_size << "\n";
    };
    StatusOr<gcs::ObjectMetadata> metadata =
        rewriter.ResultWithProgressCallback(std::move(callback));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << metadata->name() << " in bucket "
              << metadata->bucket() << "\nFull Metadata: " << *metadata << "\n";
  }

Parameters
Name	Description
source_bucket_name	std::string the name of the bucket containing the source object.
source_object_name	std::string the name of the source object.
destination_bucket_name	std::string where the destination object will be located.
destination_object_name	std::string what to name the destination object.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include DestinationKmsKeyName, DestinationPredefinedAcl, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfSourceGenerationMatch, IfSourceGenerationNotMatch, IfSourceMetagenerationMatch, IfSourceMetagenerationNotMatch, MaxBytesRewrittenPerCall, Projection, SourceEncryptionKey, SourceGeneration, UserProject, and WithObjectMetadata.
typename...

Returns
Type	Description
ObjectRewriter

ResumeRewriteObject(std::string, std::string, std::string, std::string, std::string, Options &&...)

Creates an ObjectRewriter to resume a previously created rewrite.

Applications use this function to resume a rewrite operation, possibly created with RewriteObject(). Rewrite can reliably copy objects across location boundaries, and can rewrite objects with different encryption keys. For large objects this operation can take a long time, thus applications should consider checkpointing the rewrite token (accessible in the ObjectRewriter) and restarting the operation in the event the program is terminated.

Note: Application developers should be aware that rewriting large objects may take multiple hours. Multiple calls to ObjectRewriter::Iterate() may be required to completely rewrite an object.

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name,
     std::string const& rewrite_token) {
    gcs::ObjectRewriter rewriter = client.ResumeRewriteObject(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name, rewrite_token,
        gcs::MaxBytesRewrittenPerCall(1024 * 1024));

    auto callback = [](StatusOr<gcs::RewriteProgress> progress) {
      if (!progress) throw std::move(progress).status();
      std::cout << "Rewrote " << progress->total_bytes_rewritten << "/"
                << progress->object_size << "\n";
    };
    StatusOr<gcs::ObjectMetadata> metadata =
        rewriter.ResultWithProgressCallback(std::move(callback));
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << metadata->name() << " in bucket "
              << metadata->bucket() << "\nFull Metadata: " << *metadata << "\n";
  }

Parameters
Name	Description
source_bucket_name	std::string the name of the bucket containing the source object.
source_object_name	std::string the name of the source object.
destination_bucket_name	std::string where the destination object will be located.
destination_object_name	std::string what to name the destination object.
rewrite_token	std::string the token from a previous successful rewrite iteration. Can be the empty string, in which case this starts a new rewrite operation.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include DestinationKmsKeyName, DestinationPredefinedAcl, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfSourceGenerationMatch, IfSourceGenerationNotMatch, IfSourceMetagenerationMatch, IfSourceMetagenerationNotMatch, MaxBytesRewrittenPerCall, Projection, SourceEncryptionKey, SourceGeneration, UserProject, and WithObjectMetadata.
typename...

Returns
Type	Description
ObjectRewriter

RewriteObjectBlocking(std::string, std::string, std::string, std::string, Options &&...)

Rewrites the object, blocking until the rewrite completes, and returns the resulting ObjectMetadata.

Applications use this function to reliably copy objects across location boundaries, and to rewrite objects with different encryption keys. The operation blocks until the rewrite completes, and returns the resulting ObjectMetadata.

Note: Application developers should be aware that rewriting large objects may take multiple hours. In such cases the application should consider using RewriteObject() or ResumeRewriteObject().

Idempotency

This operation is only idempotent if restricted by pre-conditions, in this case, IfGenerationMatch.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& source_bucket_name,
     std::string const& source_object_name,
     std::string const& destination_bucket_name,
     std::string const& destination_object_name) {
    StatusOr<gcs::ObjectMetadata> metadata = client.RewriteObjectBlocking(
        source_bucket_name, source_object_name, destination_bucket_name,
        destination_object_name);
    if (!metadata) throw std::move(metadata).status();

    std::cout << "Rewrote object " << destination_object_name
              << " Metadata: " << *metadata << "\n";
  }

Example: using rewrite object to rotate the encryption key

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& old_key_base64,
     std::string const& new_key_base64) {
    StatusOr<gcs::ObjectMetadata> object_metadata =
        client.RewriteObjectBlocking(
            bucket_name, object_name, bucket_name, object_name,
            gcs::SourceEncryptionKey::FromBase64Key(old_key_base64),
            gcs::EncryptionKey::FromBase64Key(new_key_base64));
    if (!object_metadata) throw std::move(object_metadata).status();

    std::cout << "Rotated key on object " << object_metadata->name()
              << " in bucket " << object_metadata->bucket()
              << "\nFull Metadata: " << *object_metadata << "\n";
  }

Example: using rewrite object to rename an object

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& old_object_name, std::string const& new_object_name) {
    StatusOr<gcs::ObjectMetadata> metadata = client.RewriteObjectBlocking(
        bucket_name, old_object_name, bucket_name, new_object_name);
    if (!metadata) throw std::move(metadata).status();

    google::cloud::Status status =
        client.DeleteObject(bucket_name, old_object_name);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "Renamed " << old_object_name << " to " << new_object_name
              << " in bucket " << bucket_name << "\n";
  }

Parameters
Name	Description
source_bucket_name	std::string the name of the bucket containing the source object.
source_object_name	std::string the name of the source object.
destination_bucket_name	std::string where the destination object will be located.
destination_object_name	std::string what to name the destination object.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include DestinationKmsKeyName, DestinationPredefinedAcl, EncryptionKey, IfGenerationMatch, IfGenerationNotMatch, IfMetagenerationMatch, IfSourceGenerationMatch, IfSourceGenerationNotMatch, IfSourceMetagenerationMatch, IfSourceMetagenerationNotMatch, MaxBytesRewrittenPerCall, Projection, SourceEncryptionKey, SourceGeneration, UserProject, and WithObjectMetadata.
typename...

Returns
Type	Description
StatusOr< ObjectMetadata >	The metadata of the newly created object.

ListBucketAcl(std::string const &, Options &&...)

Retrieves the list of BucketAccessControl items for a bucket.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<std::vector<gcs::BucketAccessControl>> items =
        client.ListBucketAcl(bucket_name);

    if (!items) throw std::move(items).status();
    std::cout << "ACLs for bucket=" << bucket_name << "\n";
    for (gcs::BucketAccessControl const& acl : *items) {
      std::cout << acl.role() << ":" << acl.entity() << "\n";
    }
  }

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< std::vector< BucketAccessControl > >

CreateBucketAcl(std::string const &, std::string const &, std::string const &, Options &&...)

Creates a new entry in a bucket ACL.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::BucketAccessControl> bucket_acl =
        client.CreateBucketAcl(bucket_name, entity, role);

    if (!bucket_acl) throw std::move(bucket_acl).status();
    std::cout << "Role " << bucket_acl->role() << " granted to "
              << bucket_acl->entity() << " on bucket " << bucket_acl->bucket()
              << "\n"
              << "Full attributes: " << *bucket_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
entity	std::string const & the name of the entity added to the ACL.
role	std::string const & the role of the entity.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< BucketAccessControl >

DeleteBucketAcl(std::string const &, std::string const &, Options &&...)

Deletes an entry from a bucket ACL.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    google::cloud::Status status = client.DeleteBucketAcl(bucket_name, entity);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted ACL entry for " << entity << " in bucket "
              << bucket_name << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
entity	std::string const & the name of the entity added to the ACL.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
Status

GetBucketAcl(std::string const &, std::string const &, Options &&...)

Gets the value of an existing bucket ACL.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    StatusOr<gcs::BucketAccessControl> acl =
        client.GetBucketAcl(bucket_name, entity);

    if (!acl) throw std::move(acl).status();
    std::cout << "ACL entry for " << acl->entity() << " in bucket "
              << acl->bucket() << " is " << *acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket to query.
entity	std::string const & the name of the entity to query.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< BucketAccessControl >

UpdateBucketAcl(std::string const &, BucketAccessControl const &, Options &&...)

Updates the value of an existing bucket ACL.

Note: For changing BucketAccessControl, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    gcs::BucketAccessControl desired_acl =
        gcs::BucketAccessControl().set_entity(entity).set_role(role);

    StatusOr<gcs::BucketAccessControl> updated_acl =
        client.UpdateBucketAcl(bucket_name, desired_acl);

    if (!updated_acl) throw std::move(updated_acl).status();
    std::cout << "Bucket ACL updated. The ACL entry for "
              << updated_acl->entity() << " in bucket " << updated_acl->bucket()
              << " is " << *updated_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/json_api/v1/bucketAccessControls for additional details on what fields are writeable.

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
acl	BucketAccessControl const & the new ACL value. Note that only the writable values of the ACL will be modified by the server.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< BucketAccessControl >

PatchBucketAcl(std::string const &, std::string const &, BucketAccessControl const &, BucketAccessControl const &, Options &&...)

Patches the value of an existing bucket ACL.

Computes the delta between a previous value for an BucketAccessControl and the new value for an BucketAccessControl and apply that delta.

Note: For changing BucketAccessControl, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::BucketAccessControl> original_acl =
        client.GetBucketAcl(bucket_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    auto new_acl = *original_acl;
    new_acl.set_role(role);

    StatusOr<gcs::BucketAccessControl> patched_acl =
        client.PatchBucketAcl(bucket_name, entity, *original_acl, new_acl);

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in bucket "
              << patched_acl->bucket() << " is now " << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/json_api/v1/bucketAccessControls for additional details on what fields are writeable.

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
entity	std::string const & the identifier for the user, group, service account, or predefined set of actors holding the permission.
original_acl	BucketAccessControl const & the original ACL value.
new_acl	BucketAccessControl const & the new ACL value. Note that only changes on writeable fields will be accepted by the server.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject, and the standard options available to all operations.
typename...

Returns
Type	Description
StatusOr< BucketAccessControl >

PatchBucketAcl(std::string const &, std::string const &, BucketAccessControlPatchBuilder const &, Options &&...)

Patches the value of an existing bucket ACL.

This API allows the application to patch an BucketAccessControl without having to read the current value.

Note: For changing BucketAccessControl, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::BucketAccessControl> patched_acl = client.PatchBucketAcl(
        bucket_name, entity,
        gcs::BucketAccessControlPatchBuilder().set_role(role));

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in bucket "
              << patched_acl->bucket() << " is now " << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/json_api/v1/bucketAccessControls for additional details on what fields are writeable.

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
entity	std::string const & the identifier for the user, group, service account, or predefined set of actors holding the permission.
builder	BucketAccessControlPatchBuilder const & a builder ready to create the patch.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, UserProject, IfMatchEtag, and IfNoneMatchEtag.
typename...

Returns
Type	Description
StatusOr< BucketAccessControl >

ListObjectAcl(std::string const &, std::string const &, Options &&...)

Retrieves the list of ObjectAccessControl items for an object.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name) {
    StatusOr<std::vector<gcs::ObjectAccessControl>> items =
        client.ListObjectAcl(bucket_name, object_name);

    if (!items) throw std::move(items).status();
    std::cout << "ACLs for object=" << object_name << " in bucket "
              << bucket_name << "\n";
    for (gcs::ObjectAccessControl const& acl : *items) {
      std::cout << acl.role() << ":" << acl.entity() << "\n";
    }
  }

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object to be deleted.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, and UserProject.
typename...

Returns
Type	Description
StatusOr< std::vector< ObjectAccessControl > >

CreateObjectAcl(std::string const &, std::string const &, std::string const &, std::string const &, Options &&...)

Creates a new entry in the object ACL.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> object_acl =
        client.CreateObjectAcl(bucket_name, object_name, entity, role);

    if (!object_acl) throw std::move(object_acl).status();
    std::cout << "Role " << object_acl->role() << " granted to "
              << object_acl->entity() << " on " << object_acl->object()
              << "\nFull attributes: " << *object_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object.
entity	std::string const & the name of the entity added to the ACL.
role	std::string const & the role of the entity.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, and UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

DeleteObjectAcl(std::string const &, std::string const &, std::string const &, Options &&...)

Deletes one access control entry in one object.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity) {
    google::cloud::Status status =
        client.DeleteObjectAcl(bucket_name, object_name, entity);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted ACL entry for " << entity << " in object "
              << object_name << " in bucket " << bucket_name << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object to be deleted.
entity	std::string const & the name of the entity (user, team, group) to be removed from the Object's ACL.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, and UserProject.
typename...

Returns
Type	Description
Status

GetObjectAcl(std::string const &, std::string const &, std::string const &, Options &&...)

Gets the value of an existing object ACL.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity) {
    StatusOr<gcs::ObjectAccessControl> acl =
        client.GetObjectAcl(bucket_name, object_name, entity);

    if (!acl) throw std::move(acl).status();
    std::cout << "ACL entry for " << acl->entity() << " in object "
              << acl->object() << " in bucket " << acl->bucket() << " is "
              << *acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object.
entity	std::string const & the name of the entity added to the ACL.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, and UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

UpdateObjectAcl(std::string const &, std::string const &, ObjectAccessControl const &, Options &&...)

Updates the value of an existing object ACL.

Note: For changing ObjectAccessControl, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> current_acl =
        client.GetObjectAcl(bucket_name, object_name, entity);

    if (!current_acl) throw std::move(current_acl).status();
    current_acl->set_role(role);

    StatusOr<gcs::ObjectAccessControl> updated_acl =
        client.UpdateObjectAcl(bucket_name, object_name, *current_acl);

    if (!updated_acl) throw std::move(updated_acl).status();
    std::cout << "ACL entry for " << updated_acl->entity() << " in object "
              << updated_acl->object() << " in bucket " << updated_acl->bucket()
              << " is now " << *updated_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

See Also

https://cloud.google.com/storage/docs/json_api/v1/objectAccessControls for additional details on what fields are writeable.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object.
acl	ObjectAccessControl const & the new ACL value. Note that only the writable values of the ACL will be modified by the server.
options	Options &&... a list of optional query parameters and/or request Valid types for this operation include Generation, and UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

PatchObjectAcl(std::string const &, std::string const &, std::string const &, ObjectAccessControl const &, ObjectAccessControl const &, Options &&...)

Patches the value of an existing object ACL.

Compute the delta between a previous value for an ObjectAccessControl and the new value for an ObjectAccessControl and apply that delta.

Note: For changing ObjectAccessControl, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> original_acl =
        client.GetObjectAcl(bucket_name, object_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    gcs::ObjectAccessControl new_acl = *original_acl;
    new_acl.set_role(role);

    StatusOr<gcs::ObjectAccessControl> patched_acl = client.PatchObjectAcl(
        bucket_name, object_name, entity, *original_acl, new_acl);

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in object "
              << patched_acl->object() << " in bucket " << patched_acl->bucket()
              << " is now " << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

See Also

https://cloud.google.com/storage/docs/json_api/v1/objectAccessControls for additional details on what fields are writeable.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object.
entity	std::string const & the identifier for the user, group, service account, or predefined set of actors holding the permission.
original_acl	ObjectAccessControl const & the original ACL value.
new_acl	ObjectAccessControl const & the new ACL value. Note that only changes on writeable fields will be accepted by the server.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, UserProject, IfMatchEtag, and IfNoneMatchEtag.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

PatchObjectAcl(std::string const &, std::string const &, std::string const &, ObjectAccessControlPatchBuilder const &, Options &&...)

Patches the value of an existing object ACL.

This API allows the application to patch an ObjectAccessControl without having to read the current value.

Note: For changing ObjectAccessControl, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& entity,
     std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> patched_acl = client.PatchObjectAcl(
        bucket_name, object_name, entity,
        gcs::ObjectAccessControlPatchBuilder().set_role(role));

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "ACL entry for " << patched_acl->entity() << " in object "
              << patched_acl->object() << " in bucket " << patched_acl->bucket()
              << " is now " << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameters.

See Also

https://cloud.google.com/storage/docs/json_api/v1/objectAccessControls for additional details on what fields are writeable.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket that contains the object.
object_name	std::string const & the name of the object.
entity	std::string const & the identifier for the user, group, service account, or predefined set of actors holding the permission.
builder	ObjectAccessControlPatchBuilder const & a builder ready to create the patch.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include Generation, UserProject, IfMatchEtag, and IfNoneMatchEtag.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

ListDefaultObjectAcl(std::string const &, Options &&...)

Retrieves the default object ACL for a bucket as a vector of ObjectAccessControl items.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<std::vector<gcs::ObjectAccessControl>> items =
        client.ListDefaultObjectAcl(bucket_name);

    if (!items) throw std::move(items).status();
    std::cout << "ACLs for bucket=" << bucket_name << "\n";
    for (gcs::ObjectAccessControl const& acl : *items) {
      std::cout << acl.role() << ":" << acl.entity() << "\n";
    }
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include IfMetagenerationMatch, IfMetagenerationNotMatch and UserProject.
typename...

Returns
Type	Description
StatusOr< std::vector< ObjectAccessControl > >

CreateDefaultObjectAcl(std::string const &, std::string const &, std::string const &, Options &&...)

Creates a new entry in the default object ACL for a bucket.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> default_object_acl =
        client.CreateDefaultObjectAcl(bucket_name, entity, role);
    if (!default_object_acl) throw std::move(default_object_acl).status();

    std::cout << "Role " << default_object_acl->role()
              << " will be granted default to " << default_object_acl->entity()
              << " on any new object created on bucket "
              << default_object_acl->bucket() << "\n"
              << "Full attributes: " << *default_object_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
entity	std::string const & the name of the entity added to the ACL.
role	std::string const & the role of the entity.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

DeleteDefaultObjectAcl(std::string const &, std::string const &, Options &&...)

Deletes an entry from the default object ACL in a bucket.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    google::cloud::Status status =
        client.DeleteDefaultObjectAcl(bucket_name, entity);

    if (!status.ok()) throw std::runtime_error(status.message());
    std::cout << "Deleted ACL entry for " << entity << " in bucket "
              << bucket_name << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
entity	std::string const & the name of the entity added to the ACL.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
Status

GetDefaultObjectAcl(std::string const &, std::string const &, Options &&...)

Gets the value of a default object ACL in a bucket.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity) {
    StatusOr<gcs::ObjectAccessControl> acl =
        client.GetDefaultObjectAcl(bucket_name, entity);

    if (!acl) throw std::move(acl).status();
    std::cout << "Default Object ACL entry for " << acl->entity()
              << " in bucket " << acl->bucket() << " is " << *acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
entity	std::string const & the name of the entity.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

UpdateDefaultObjectAcl(std::string const &, ObjectAccessControl const &, Options &&...)

Updates the value of an existing default object ACL.

The default object ACL sets the ACL for any object created in the bucket, unless a different ACL is specified when the object is created.

Note: For changing default object access controls, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> original_acl =
        client.GetDefaultObjectAcl(bucket_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    original_acl->set_role(role);

    StatusOr<gcs::ObjectAccessControl> updated_acl =
        client.UpdateDefaultObjectAcl(bucket_name, *original_acl);
    if (!updated_acl) throw std::move(updated_acl).status();

    std::cout << "Default Object ACL entry for " << updated_acl->entity()
              << " in bucket " << updated_acl->bucket() << " is now "
              << *updated_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
acl	ObjectAccessControl const & the new ACL value. Note that only the writable values of the ACL will be modified by the server.
options	Options &&... a list of optional query parameters and/or request Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

PatchDefaultObjectAcl(std::string const &, std::string const &, ObjectAccessControl const &, ObjectAccessControl const &, Options &&...)

Patches the value of an existing default object ACL.

Compute the delta between a previous and new values for a default object access control, and apply that delta.

Note: For changing default object access controls, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> original_acl =
        client.GetDefaultObjectAcl(bucket_name, entity);
    if (!original_acl) throw std::move(original_acl).status();

    auto new_acl = *original_acl;
    new_acl.set_role(role);

    StatusOr<gcs::ObjectAccessControl> patched_acl =
        client.PatchDefaultObjectAcl(bucket_name, entity, *original_acl,
                                     new_acl);

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "Default Object ACL entry for " << patched_acl->entity()
              << " in bucket " << patched_acl->bucket() << " is now "
              << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
entity	std::string const & the identifier for the user, group, service account, or predefined set of actors holding the permission.
original_acl	ObjectAccessControl const & the original ACL value.
new_acl	ObjectAccessControl const & the new ACL value. Note that only changes on writeable fields will be accepted by the server.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject, as well as the standard parameters, such as IfMatchEtag, and IfNoneMatchEtag.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

PatchDefaultObjectAcl(std::string const &, std::string const &, ObjectAccessControlPatchBuilder const &, Options &&...)

Patches the value of an existing default object ACL.

This API allows the application to patch an ObjectAccessControl without having to read the current value.

Note: For changing default object access controls, the Patch and Update APIs basically offer the same functionality. The only field that can be modified by either API is role, and it may only be set to a new value (it cannot be removed). The API is offered for consistency with the other resource types where Patch and Update APIs have different semantics.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& entity, std::string const& role) {
    StatusOr<gcs::ObjectAccessControl> patched_acl =
        client.PatchDefaultObjectAcl(
            bucket_name, entity,
            gcs::ObjectAccessControlPatchBuilder().set_role(role));

    if (!patched_acl) throw std::move(patched_acl).status();
    std::cout << "Default Object ACL entry for " << patched_acl->entity()
              << " in bucket " << patched_acl->bucket() << " is now "
              << *patched_acl << "\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/create-manage-lists#defaultobjects

See Also

https://cloud.google.com/storage/docs/access-control/lists#scopes for the format of the entity parameter.

See Also

https://cloud.google.com/storage/docs/access-control/lists#permissions for the format of the role parameter.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
entity	std::string const & the identifier for the user, group, service account, or predefined set of actors holding the permission.
builder	ObjectAccessControlPatchBuilder const & a builder ready to create the patch.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject, as well as the standard parameters, such as IfMatchEtag, and IfNoneMatchEtag.
typename...

Returns
Type	Description
StatusOr< ObjectAccessControl >

GetServiceAccountForProject(std::string const &, Options &&...)

Gets the GCS service account for a given project.

A service account is a special Google account that belongs to your application, virtual machine, or to a Google service when acting on your behalf. This API allows you to discover the GCS service account for the project_id project.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& project_id) {
    StatusOr<gcs::ServiceAccount> account =
        client.GetServiceAccountForProject(project_id);
    if (!account) throw std::move(account).status();

    std::cout << "The service account details for project " << project_id
              << " are " << *account << "\n";
  }

See Also

https://cloud.google.com/iam/docs/service-accounts for general information on Google Cloud Platform service accounts.

Parameters
Name	Description
project_id	std::string const & the project to query.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject. OverrideDefaultProject is accepted, but has no effect.
typename...

Returns
Type	Description
StatusOr< ServiceAccount >

GetServiceAccount(Options &&...)

Gets the GCS service account for the default project.

A service account is a special Google account that belongs to your application, virtual machine, or to a Google service when acting on your behalf. This API allows you to discover the GCS service account for the default project associated with this object.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

• Any parameters of type OverrideDefaultProject, with a value.
• Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
• Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
• The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client) {
    StatusOr<gcs::ServiceAccount> account = client.GetServiceAccount();
    if (!account) throw std::move(account).status();

    std::cout << "The service account details are " << *account << "\n";
  }

See Also

https://cloud.google.com/iam/docs/service-accounts for general information on Google Cloud Platform service accounts.

Parameters
Name	Description
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject, and OverrideDefaultProject.
typename...

Returns
Type	Description
StatusOr< ServiceAccount >

ListHmacKeys(Options &&...)

List the available HMAC keys.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

• Any parameters of type OverrideDefaultProject, with a value.
• Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
• Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
• The value from the GOOGLE_CLOUD_PROJECT environment variable.

Warning: This GCS feature is not GA, it is subject to change without notice.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client) {
    int count = 0;
    gcs::ListHmacKeysReader hmac_keys_list = client.ListHmacKeys();
    for (auto& key : hmac_keys_list) {
      if (!key) throw std::move(key).status();

      std::cout << "service_account_email = " << key->service_account_email()
                << "\naccess_id = " << key->access_id() << "\n";
      ++count;
    }
    if (count == 0) {
      std::cout << "No HMAC keys in default project\n";
    }
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& service_account) {
    int count = 0;
    gcs::ListHmacKeysReader hmac_keys_list =
        client.ListHmacKeys(gcs::ServiceAccountFilter(service_account));
    for (auto& key : hmac_keys_list) {
      if (!key) throw std::move(key).status();

      std::cout << "service_account_email = " << key->service_account_email()
                << "\naccess_id = " << key->access_id() << "\n";
      ++count;
    }
    if (count == 0) {
      std::cout << "No HMAC keys for service account " << service_account
                << " in default project\n";
    }
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Parameters
Name	Description
options	Options &&... a list of optional query parameters and/or request headers. In addition to the options common to all requests, this operation accepts DeletedMaxResults, OverrideDefaultProject, and ServiceAccountFilter.
typename...

Returns
Type	Description
ListHmacKeysReader	A range to iterate over the available HMAC keys.

CreateHmacKey(std::string, Options &&...)

Create a new HMAC key.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

• Any parameters of type OverrideDefaultProject, with a value.
• Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
• Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
• The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This operation is not idempotent. Retrying the operation will create a new key each time.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  return [](gcs::Client client, std::string const& service_account_email) {
    StatusOr<std::pair<gcs::HmacKeyMetadata, std::string>> key_info =
        client.CreateHmacKey(service_account_email);
    if (!key_info) throw std::move(key_info).status();

    std::cout << "The base64 encoded secret is: " << key_info->second
              << "\nDo not miss that secret, there is no API to recover it."
              << "\nThe HMAC key metadata is: " << key_info->first << "\n";
    return key_info->first.access_id();
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  return [](gcs::Client client, std::string const& project_id,
            std::string const& service_account_email) {
    StatusOr<std::pair<gcs::HmacKeyMetadata, std::string>> hmac_key_details =
        client.CreateHmacKey(service_account_email,
                             gcs::OverrideDefaultProject(project_id));
    if (!hmac_key_details) throw std::move(hmac_key_details).status();

    std::cout << "The base64 encoded secret is: " << hmac_key_details->second
              << "\nDo not miss that secret, there is no API to recover it."
              << "\nThe HMAC key metadata is: " << hmac_key_details->first
              << "\n";
    return hmac_key_details->first.access_id();
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Parameters
Name	Description
service_account	std::string the service account email where you want to create the new HMAC key.
options	Options &&... a list of optional query parameters and/or request headers. In addition to the options common to all requests, this operation accepts OverrideDefaultProject.
typename...

Returns
Type	Description
StatusOr< std::pair< HmacKeyMetadata, std::string > >	This operation returns the new HMAC key metadata and the HMAC key secret (encoded as a base64 string). This is the only request that returns the secret.

DeleteHmacKey(std::string, Options &&...)

Delete a HMAC key in the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

• Any parameters of type OverrideDefaultProject, with a value.
• Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
• Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
• The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This operation is always idempotent. An access id identifies a single HMAC key, calling the operation multiple times can succeed only once.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& access_id) {
    google::cloud::Status status = client.DeleteHmacKey(access_id);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "The key is deleted, though it may still appear"
              << " in ListHmacKeys() results.\n";
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Parameters
Name	Description
access_id	std::string the HMAC key access_id() that you want to delete. Each HMAC key is assigned an access_id() attribute at creation time.
options	Options &&... a list of optional query parameters and/or request headers. In addition to the options common to all requests, this operation accepts OverrideDefaultProject.
typename...

Returns
Type	Description
Status	This operation returns the new HMAC key metadata.

GetHmacKey(std::string, Options &&...)

Get an existing HMAC key in the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

• Any parameters of type OverrideDefaultProject, with a value.
• Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
• Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
• The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This is a read-only operation and therefore it is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& access_id) {
    StatusOr<gcs::HmacKeyMetadata> hmac_key = client.GetHmacKey(access_id);
    if (!hmac_key) throw std::move(hmac_key).status();

    std::cout << "The HMAC key metadata is: " << *hmac_key << "\n";
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Parameters
Name	Description
access_id	std::string the HMAC key access_id() that you want to delete. Each HMAC key is assigned an access_id() attribute at creation time.
options	Options &&... a list of optional query parameters and/or request headers. In addition to the options common to all requests, this operation accepts OverrideDefaultProject.
typename...

Returns
Type	Description
StatusOr< HmacKeyMetadata >	This operation returns the new HMAC key metadata.

UpdateHmacKey(std::string, HmacKeyMetadata, Options &&...)

Update an existing HMAC key in the default project.

This function will return an error if it cannot determine the "default" project. The default project is found by looking, in order, for:

• Any parameters of type OverrideDefaultProject, with a value.
• Any google::cloud::storage::ProjectIdOption value in any parameters of type google::cloud::Options{}.
• Any google::cloud::storage::ProjectIdOption value provided in the google::cloud::Options{} passed to the constructor.
• The value from the GOOGLE_CLOUD_PROJECT environment variable.

Idempotency

This operation is only idempotent if the etag attribute in resource is set, or if the IfMatchEtag option is set.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& access_id,
     std::string const& state) {
    StatusOr<gcs::HmacKeyMetadata> updated = client.UpdateHmacKey(
        access_id, gcs::HmacKeyMetadata().set_state(state));
    if (!updated) throw std::move(updated).status();

    std::cout << "The updated HMAC key metadata is: " << *updated << "\n";
  }

See Also

https://cloud.google.com/storage/docs/authentication/hmackeys for general information on using HMAC keys for Google Cloud Platform service accounts authentication.

See Also

https://cloud.google.com/storage/docs/authentication/managing-hmackeys for a detailed description on how to use the feature.

Parameters
Name	Description
access_id	std::string the HMAC key access_id() that you want to delete. Each HMAC key is assigned an access_id() attribute at creation time.
resource	HmacKeyMetadata the desired changes to the HMAC key resource. Only the state field may be changed. The etag field may be set but it is only used as a pre-condition, the application cannot set the etag.
options	Options &&... a list of optional query parameters and/or request headers. In addition to the options common to all requests, this operation accepts OverrideDefaultProject.
typename...

Returns
Type	Description
StatusOr< HmacKeyMetadata >	This operation returns the new HMAC key metadata.

CreateV2SignedUrl(std::string, std::string, std::string, Options &&...)

Create a V2 signed URL for the given parameters.

Note: By default URLs created with this function expire after 7 days.

Note: The application must ensure that any URL created with this function is a valid request via the XML API. For example, the options for bucket requests may include a sub-resource (e.g. WithBilling()) but not all sub-resources are valid for objects. Likewise, only a single sub-resource may be retrieved in each request.

Helper Functions

The following functions create a AddSubResourceOption with less opportunities for typos in the sub-resource name: WithAcl(), WithBilling(), WithCompose(), WithCors(), WithEncryption(), WithEncryptionConfig(), WithLifecycle(), WithLocation(), WithLogging(), WithStorageClass(), and WithTagging().

Likewise, the following helper functions can create properly formatted AddExtensionHeaderOption objects: WithGeneration(), WithGenerationMarker(), WithMarker(), WithResponseContentDisposition(), WithResponseContentType(), and WithUserProject().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV2SignedUrl(
        "GET", bucket_name, object_name,
        gcs::ExpirationTime(std::chrono::system_clock::now() +
                            std::chrono::minutes(15)),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl '" << *signed_url << "'\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV2SignedUrl(
        "PUT", bucket_name, object_name,
        gcs::ExpirationTime(std::chrono::system_clock::now() +
                            std::chrono::minutes(15)),
        gcs::ContentType("application/octet-stream"),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl -X PUT -H 'Content-Type: application/octet-stream'"
              << " --upload-file my-file '" << *signed_url << "'\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/signed-urls for a general description of signed URLs and how they can be used.

See Also

https://cloud.google.com/storage/docs/xml-api/overview for a detailed description of the XML API.

Parameters
Name	Description
verb	std::string the operation allowed through this signed URL, GET, POST, PUT, HEAD, etc. are valid values.
bucket_name	std::string the name of the bucket.
object_name	std::string the name of the object, note that the object may not exist for signed URLs that upload new objects. Use an empty string for requests that only affect a bucket.
options	Options &&... a list of optional parameters for the signed URL, this include: ExpirationTime, MD5HashValue, ContentType, SigningAccount, SigningAccountDelegates, AddExtensionHeaderOption, AddQueryParameterOption, and AddSubResourceOption. Note that only the last AddSubResourceOption option has any effect.
typename...

Returns
Type	Description
StatusOr< std::string >	the signed URL.

CreateV4SignedUrl(std::string, std::string, std::string, Options &&...)

Create a V4 signed URL for the given parameters.

Note: By default URLs created with this function expire after 7 days.

Note: The application must ensure that any URL created with this function is a valid request via the XML API. For example, the options for bucket requests may include a sub-resource (e.g. WithBilling()) but not all sub-resources are valid for objects. Likewise, only a single sub-resource may be retrieved in each request.

Helper Functions

The following functions create a AddSubResourceOption with less opportunities for typos in the sub-resource name: WithAcl(), WithBilling(), WithCompose(), WithCors(), WithEncryption(), WithEncryptionConfig(), WithLifecycle(), WithLocation(), WithLogging(), WithStorageClass(), and WithTagging().

Likewise, the following helper functions can create properly formatted AddExtensionHeaderOption objects: WithGeneration(), WithGenerationMarker(), WithMarker(), WithResponseContentDisposition(), WithResponseContentType(), and WithUserProject().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV4SignedUrl(
        "GET", bucket_name, object_name,
        gcs::SignedUrlDuration(std::chrono::minutes(15)),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl '" << *signed_url << "'\n";
  }

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& object_name, std::string const& signing_account) {
    StatusOr<std::string> signed_url = client.CreateV4SignedUrl(
        "PUT", bucket_name, object_name,
        gcs::SignedUrlDuration(std::chrono::minutes(15)),
        gcs::AddExtensionHeader("content-type", "application/octet-stream"),
        gcs::SigningAccount(signing_account));

    if (!signed_url) throw std::move(signed_url).status();
    std::cout << "The signed url is: " << *signed_url << "\n\n"
              << "You can use this URL with any user agent, for example:\n"
              << "curl -X PUT -H 'Content-Type: application/octet-stream'"
              << " --upload-file my-file '" << *signed_url << "'\n";
  }

See Also

https://cloud.google.com/storage/docs/access-control/signed-urls for a general description of signed URLs and how they can be used.

See Also

https://cloud.google.com/storage/docs/xml-api/overview for a detailed description of the XML API.

Parameters
Name	Description
verb	std::string the operation allowed through this signed URL, GET, POST, PUT, HEAD, etc. are valid values.
bucket_name	std::string the name of the bucket.
object_name	std::string the name of the object, note that the object may not exist for signed URLs that upload new objects. Use an empty string for requests that only affect a bucket.
options	Options &&... a list of optional parameters for the signed URL, this include: SignedUrlTimestamp, SignedUrlDuration, MD5HashValue, ContentType, SigningAccount, SigningAccountDelegates, AddExtensionHeaderOption, AddQueryParameterOption, and AddSubResourceOption. Note that only the last AddSubResourceOption option has any effect.
typename...

Returns
Type	Description
StatusOr< std::string >	the signed URL.

ListNotifications(std::string const &, Options &&...)

Retrieves the list of Notifications for a Bucket.

Cloud Pub/Sub Notifications sends information about changes to objects in your buckets to Google Cloud Pub/Sub service.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name) {
    StatusOr<std::vector<gcs::NotificationMetadata>> items =
        client.ListNotifications(bucket_name);
    if (!items) throw std::move(items).status();

    std::cout << "Notifications for bucket=" << bucket_name << "\n";
    for (gcs::NotificationMetadata const& notification : *items) {
      std::cout << notification << "\n";
    }
  }

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< std::vector< NotificationMetadata > >

CreateNotification(std::string const &, std::string const &, NotificationMetadata, Options &&...)

Creates a new notification config for a Bucket.

Cloud Pub/Sub Notifications send information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& topic_name) {
    StatusOr<gcs::NotificationMetadata> notification =
        client.CreateNotification(bucket_name, topic_name,
                                  gcs::NotificationMetadata());
    if (!notification) throw std::move(notification).status();

    std::cout << "Successfully created notification " << notification->id()
              << " for bucket " << bucket_name << "\n";
    std::cout << "Full details for the notification:\n"
              << *notification << "\n";
  }

See Also

https://cloud.google.com/storage/docs/pubsub-notifications for general information on Cloud Pub/Sub Notifications for Google Cloud Storage.

See Also

https://cloud.google.com/pubsub/ for general information on Google Cloud Pub/Sub service.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
topic_name	std::string const & the Google Cloud Pub/Sub topic that will receive the notifications. This requires the full name of the topic, i.e.: projects/<PROJECT_ID>/topics/<TOPIC_ID>.
metadata	NotificationMetadata define any optional parameters for the notification, such as the list of event types, or any custom attributes.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< NotificationMetadata >

CreateNotification(std::string const &, std::string const &, std::string const &, NotificationMetadata, Options &&...)

Creates a new notification config for a Bucket.

Cloud Pub/Sub Notifications send information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options.

Idempotency

This operation is only idempotent if restricted by pre-conditions. There are no pre-conditions for this operation that can make it idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& topic_name) {
    StatusOr<gcs::NotificationMetadata> notification =
        client.CreateNotification(bucket_name, topic_name,
                                  gcs::NotificationMetadata());
    if (!notification) throw std::move(notification).status();

    std::cout << "Successfully created notification " << notification->id()
              << " for bucket " << bucket_name << "\n";
    std::cout << "Full details for the notification:\n"
              << *notification << "\n";
  }

See Also

https://cloud.google.com/storage/docs/pubsub-notifications for general information on Cloud Pub/Sub Notifications for Google Cloud Storage.

See Also

https://cloud.google.com/pubsub/ for general information on Google Cloud Pub/Sub service.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
topic_name	std::string const & the Google Cloud Pub/Sub topic that will receive the notifications. This requires the full name of the topic, i.e.: projects/<PROJECT_ID>/topics/<TOPIC_ID>.
payload_format	std::string const &
metadata	NotificationMetadata define any optional parameters for the notification, such as the list of event types, or any custom attributes.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< NotificationMetadata >

GetNotification(std::string const &, std::string const &, Options &&...)

Gets the details about a notification config in a given Bucket.

Cloud Pub/Sub Notifications sends information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options. This function fetches the detailed information for a given notification config.

Idempotency

This is a read-only operation and is always idempotent.

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& notification_id) {
    StatusOr<gcs::NotificationMetadata> notification =
        client.GetNotification(bucket_name, notification_id);
    if (!notification) throw std::move(notification).status();

    std::cout << "Notification " << notification->id() << " for bucket "
              << bucket_name << "\n";
    if (notification->object_name_prefix().empty()) {
      std::cout << "This notification is sent for all objects in the bucket\n";
    } else {
      std::cout << "This notification is sent only for objects starting with"
                << " the prefix " << notification->object_name_prefix() << "\n";
    }
    std::cout << "Full details for the notification:\n"
              << *notification << "\n";
  }

See Also

https://cloud.google.com/storage/docs/pubsub-notifications for general information on Cloud Pub/Sub Notifications for Google Cloud Storage.

See Also

https://cloud.google.com/pubsub/ for general information on Google Cloud Pub/Sub service.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
notification_id	std::string const & the id of the notification config.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
StatusOr< NotificationMetadata >

DeleteNotification(std::string const &, std::string const &, Options &&...)

Delete an existing notification config in a given Bucket.

Cloud Pub/Sub Notifications sends information about changes to objects in your buckets to Google Cloud Pub/Sub service. You can create multiple notifications per Bucket, with different topics and filtering options. This function deletes one of the notification configs.

Idempotency

This operation is always idempotent because it only acts on a specific notification_id, the state after calling this function multiple times is to delete that notification. New notifications get different ids.

Example

  namespace gcs = ::google::cloud::storage;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& notification_id) {
    google::cloud::Status status =
        client.DeleteNotification(bucket_name, notification_id);
    if (!status.ok()) throw std::runtime_error(status.message());

    std::cout << "Successfully deleted notification " << notification_id
              << " on bucket " << bucket_name << "\n";
  }

See Also

https://cloud.google.com/storage/docs/pubsub-notifications for general information on Cloud Pub/Sub Notifications for Google Cloud Storage.

See Also

https://cloud.google.com/pubsub/ for general information on Google Cloud Pub/Sub service.

Parameters
Name	Description
bucket_name	std::string const & the name of the bucket.
notification_id	std::string const & the id of the notification config.
options	Options &&... a list of optional query parameters and/or request headers. Valid types for this operation include UserProject.
typename...

Returns
Type	Description
Status

CreateSignedPolicyDocument(PolicyDocument, Options &&...)

Create a signed policy document.

Note: The application must ensure that any document created with this function contains valid conditions. This function does not do any error checking, e.g. that a ExactMatchObject() condition contains two elements. Using the provided helper functions can prevent errors.

Note: It is the application's responsibility to construct a POST request based on the value returned by this function. For example, a web application can create a HTML form containing these fields, the result of which is a POST request to GCS.

Helper Functions

The following functions create a PolicyDocumentCondition with less opportunities for typos: StartsWith(), ExactMatchObject(), ExactMatch(), ContentLengthRange().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& signing_account) {
    StatusOr<gcs::PolicyDocumentResult> document =
        client.CreateSignedPolicyDocument(
            gcs::PolicyDocument{
                std::chrono::system_clock::now() + std::chrono::minutes(15),
                {
                    gcs::PolicyDocumentCondition::StartsWith("key", ""),
                    gcs::PolicyDocumentCondition::ExactMatchObject(
                        "acl", "bucket-owner-read"),
                    gcs::PolicyDocumentCondition::ExactMatchObject("bucket",
                                                                   bucket_name),
                    gcs::PolicyDocumentCondition::ExactMatch("Content-Type",
                                                             "image/jpeg"),
                    gcs::PolicyDocumentCondition::ContentLengthRange(0,
                                                                     1000000),
                }},
            gcs::SigningAccount(signing_account));
    if (!document) throw std::move(document).status();

    std::cout << "The signed document is: " << *document << "\n\n"
              << "You can use this with an HTML form.\n";
  }

See Also

https://cloud.google.com/storage/docs/xml-api/post-object#policydocument for a general description of policy documents and how they can be used.

See Also

https://cloud.google.com/storage/docs/xml-api/overview for a detailed description of the XML API.

Parameters
Name	Description
document	PolicyDocument the policy document.
options	Options &&... a list of optional parameters, this includes: SigningAccount, and SigningAccountDelegates.
typename...

Returns
Type	Description
StatusOr< PolicyDocumentResult >

GenerateSignedPostPolicyV4(PolicyDocumentV4, Options &&...)

Create a signed V4 policy document.

Note: The application must ensure that any document created with this function contains valid conditions. This function does not do any error checking, e.g. that a ExactMatchObject() condition contains two elements. Using the provided helper functions can prevent errors.

Note: It is the application's responsibility to construct a POST request based on the value returned by this function. For example, a web application can create a HTML form containing these fields, the result of which is a POST request to GCS.

Helper Functions

The following functions create a PolicyDocumentCondition with less opportunities for typos: StartsWith(), ExactMatchObject(), ExactMatch(), ContentLengthRange().

Example

  namespace gcs = ::google::cloud::storage;
  using ::google::cloud::StatusOr;
  [](gcs::Client client, std::string const& bucket_name,
     std::string const& signing_account) {
    StatusOr<gcs::PolicyDocumentV4Result> document =
        client.GenerateSignedPostPolicyV4(
            gcs::PolicyDocumentV4{
                bucket_name,
                "scan_0001.jpg",
                std::chrono::minutes(15),
                std::chrono::system_clock::now(),
                {
                    gcs::PolicyDocumentCondition::StartsWith("key", ""),
                    gcs::PolicyDocumentCondition::ExactMatchObject(
                        "acl", "bucket-owner-read"),
                    gcs::PolicyDocumentCondition::ExactMatch("Content-Type",
                                                             "image/jpeg"),
                    gcs::PolicyDocumentCondition::ContentLengthRange(0,
                                                                     1000000),
                }},
            gcs::SigningAccount(signing_account));
    if (!document) throw std::move(document).status();

    std::cout << "The signed document is: " << *document << "\n\n"
              << "You can use this with an HTML form.\n";
  }

See Also

https://cloud.google.com/storage/docs/xml-api/post-object#policydocument for a general description of policy documents and how they can be used.

See Also

https://cloud.google.com/storage/docs/xml-api/overview for a detailed description of the XML API.

Parameters
Name	Description
document	PolicyDocumentV4 the policy document.
options	Options &&... a list of optional parameters, this includes: AddExtensionFieldOption, BucketBoundHostname, PredefinedAcl, Scheme, SigningAccountDelegates, SigningAccount, VirtualHostname
typename...

Returns
Type	Description
StatusOr< PolicyDocumentV4Result >

raw_client() const

Access the underlying StorageConnection.

Deprecated: Only intended for implementors, do not use.

Returns
Type	Description
std::shared_ptr< internal::StorageConnection >

static CreateDefaultClient()

Create a Client using ClientOptions::CreateDefaultClientOptions().

Deprecated: use the constructor from google::cloud::Options instead.

Returns
Type	Description
StatusOr< Client >