Package cloud.google.com/go (v0.102.1)

Version 0.102.1

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Note: To get more information about this package, such as access to older versions, view this package on pkg.go.dev.

Package cloud is the root of the packages used to access Google Cloud Services. See https://godoc.org/cloud.google.com/go for a full list of sub-packages.

Client Options

All clients in sub-packages are configurable via client options. These options are described here: https://godoc.org/google.golang.org/api/option.

Authentication and Authorization

All the clients in sub-packages support authentication via Google Application Default Credentials (see https://cloud.google.com/docs/authentication/production), or by providing a JSON key file for a Service Account. See examples below.

Google Application Default Credentials (ADC) is the recommended way to authorize and authenticate clients. For information on how to create and obtain Application Default Credentials, see https://cloud.google.com/docs/authentication/production. Here is an example of a client using ADC to authenticate:

client, err := secretmanager.NewClient(context.Background())
if err != nil {
    // TODO: handle error.
}
_ = client // Use the client.

You can use a file with credentials to authenticate and authorize, such as a JSON key file associated with a Google service account. Service Account keys can be created and downloaded from https://console.cloud.google.com/iam-admin/serviceaccounts. This example uses the Secret Manger client, but the same steps apply to the other client libraries underneath this package. Example:

client, err := secretmanager.NewClient(context.Background(),
    option.WithCredentialsFile("/path/to/service-account-key.json"))
if err != nil {
    // TODO: handle error.
}
_ = client // Use the client.

In some cases (for instance, you don't want to store secrets on disk), you can create credentials from in-memory JSON and use the WithCredentials option. The google package in this example is at golang.org/x/oauth2/google. This example uses the Secret Manager client, but the same steps apply to the other client libraries underneath this package. Note that scopes can be found at https://developers.google.com/identity/protocols/oauth2/scopes, and are also provided in all auto-generated libraries: for example, cloud.google.com/go/secretmanager/apiv1 provides DefaultAuthScopes. Example:

ctx := context.Background()
creds, err := google.CredentialsFromJSON(ctx, []byte("JSON creds"), secretmanager.DefaultAuthScopes()...)
if err != nil {
    // TODO: handle error.
}
client, err := secretmanager.NewClient(ctx, option.WithCredentials(creds))
if err != nil {
    // TODO: handle error.
}
_ = client // Use the client.

Timeouts and Cancellation

By default, non-streaming methods, like Create or Get, will have a default deadline applied to the context provided at call time, unless a context deadline is already set. Streaming methods have no default deadline and will run indefinitely. To set timeouts or arrange for cancellation, use contexts. Transient errors will be retried when correctness allows.

Here is an example of how to set a timeout for an RPC, use context.WithTimeout:

ctx := context.Background()
// Do not set a timeout on the context passed to NewClient: dialing happens
// asynchronously, and the context is used to refresh credentials in the
// background.
client, err := secretmanager.NewClient(ctx)
if err != nil {
    // TODO: handle error.
}
// Time out if it takes more than 10 seconds to create a dataset.
tctx, cancel := context.WithTimeout(ctx, 10*time.Second)
defer cancel() // Always call cancel.

req := &secretmanagerpb.DeleteSecretRequest{Name: "projects/project-id/secrets/name"}
if err := client.DeleteSecret(tctx, req); err != nil {
    // TODO: handle error.
}

Here is an example of how to arrange for an RPC to be canceled, use context.WithCancel:

ctx := context.Background()
// Do not cancel the context passed to NewClient: dialing happens asynchronously,
// and the context is used to refresh credentials in the background.
client, err := secretmanager.NewClient(ctx)
if err != nil {
    // TODO: handle error.
}
cctx, cancel := context.WithCancel(ctx)
defer cancel() // Always call cancel.

// TODO: Make the cancel function available to whatever might want to cancel the
// call--perhaps a GUI button.
req := &secretmanagerpb.DeleteSecretRequest{Name: "projects/proj/secrets/name"}
if err := client.DeleteSecret(cctx, req); err != nil {
    // TODO: handle error.
}

To opt out of default deadlines, set the temporary environment variable GOOGLE_API_GO_EXPERIMENTAL_DISABLE_DEFAULT_DEADLINE to "true" prior to client creation. This affects all Google Cloud Go client libraries. This opt-out mechanism will be removed in a future release. File an issue at https://github.com/googleapis/google-cloud-go if the default deadlines cannot work for you.

Do not attempt to control the initial connection (dialing) of a service by setting a timeout on the context passed to NewClient. Dialing is non-blocking, so timeouts would be ineffective and would only interfere with credential refreshing, which uses the same context.

Connection Pooling

Connection pooling differs in clients based on their transport. Cloud clients either rely on HTTP or gRPC transports to communicate with Google Cloud.

Cloud clients that use HTTP (bigquery, compute, storage, and translate) rely on the underlying HTTP transport to cache connections for later re-use. These are cached to the default http.MaxIdleConns and http.MaxIdleConnsPerHost settings in http.DefaultTransport.

For gRPC clients (all others in this repo), connection pooling is configurable. Users of cloud client libraries may specify option.WithGRPCConnectionPool(n) as a client option to NewClient calls. This configures the underlying gRPC connections to be pooled and addressed in a round robin fashion.

Using the Libraries with Docker

Minimal docker images like Alpine lack CA certificates. This causes RPCs to appear to hang, because gRPC retries indefinitely. See https://github.com/googleapis/google-cloud-go/issues/928 for more information.

Debugging

To see gRPC logs, set the environment variable GRPC_GO_LOG_SEVERITY_LEVEL. See https://godoc.org/google.golang.org/grpc/grpclog for more information.

For HTTP logging, set the GODEBUG environment variable to "http2debug=1" or "http2debug=2".

Inspecting errors

Most of the errors returned by the generated clients are wrapped in an apierror.APIError (https://pkg.go.dev/github.com/googleapis/gax-go/v2/apierror) and can be further unwrapped into a grpc.Status or googleapi.Error depending on the transport used to make the call (gRPC or REST). Converting your errors to these types can be a useful way to get more information about what went wrong while debugging.

apierror.APIError gives access to specific details in the error. The transport-specific errors can still be unwrapped using the apierror.APIError.

if err != nil {
   var ae *apierror.APIError
   if errors.As(err, &ae) {
      log.Println(ae.Reason())
      log.Println(ae.Details().Help.GetLinks())
   }
}

If the gRPC transport was used, the grpc.Status can still be parsed using the status.FromError function.

if err != nil {
   if s, ok := status.FromError(err); ok {
      log.Println(s.Message())
      for _, d := range s.Proto().Details {
         log.Println(d)
      }
   }
}

If the REST transport was used, the googleapi.Error can be parsed in a similar way.

if err != nil {
   var gerr *googleapi.Error
   if errors.As(err, &gerr) {
      log.Println(gerr.Message)
   }
}

Client Stability

Clients in this repository are considered alpha or beta unless otherwise marked as stable in the README.md. Semver is not used to communicate stability of clients.

Alpha and beta clients may change or go away without notice.

Clients marked stable will maintain compatibility with future versions for as long as we can reasonably sustain. Incompatible changes might be made in some situations, including:

- Security bugs may prompt backwards-incompatible changes.

- Situations in which components are no longer feasible to maintain without making breaking changes, including removal.

- Parts of the client surface may be outright unstable and subject to change. These parts of the surface will be labeled with the note, "It is EXPERIMENTAL and subject to change or removal without notice."