Using IAM permissions

Go to concepts

This page describes how to control access to buckets and objects using Identity and Access Management (IAM) permissions. IAM allows you to control who has access to your buckets and objects.

To learn about other ways to control access to buckets and objects, read Overview of Access Control. To learn about controlling access to individual objects in your buckets, see Access Control Lists.

Note: IAM policies cannot be managed using the XML API.

Using IAM with buckets

The following sections show how to complete basic IAM tasks on buckets.

Adding a principal to a bucket-level policy

For a list of roles associated with Cloud Storage, see IAM Roles. For information on entities to which you grant IAM roles, see Principal Types.

Console

1. In the Google Cloud Console, go to the Cloud Storage Browser page.
   

   Go to Browser

2. Click the Bucket overflow menu () associated with the bucket to which you want to grant a principal a role.

3. Choose Edit bucket permissions.

4. Click the + Add principals button.

5. In the New principals field, enter one or more identities that need access to your bucket.

6. Select a role (or roles) from the Select a role drop-down menu. The roles you select appear in the pane with a short description of the permissions they grant.

7. Click Save.

To learn how to get detailed error information about failed operations in the Cloud Storage browser, see Troubleshooting.

gsutil

Use the gsutil iam ch command:

gsutil iam ch PRINCIPAL_TYPE:PRINCIPAL_NAME:IAM_ROLE gs://BUCKET_NAME

Where:

• PRINCIPAL_TYPE is the type of principal to which you are granting bucket access. For example, user.
• PRINCIPAL_NAME is the name of the principal to which you are granting bucket access. For example, [e-mail].
• IAM_ROLE is the IAM role you are granting to the principal. For example, objectViewer.
• BUCKET_NAME is the name of the bucket you are granting the principal access to. For example, my-bucket.

For more examples of how to format PRINCIPAL_TYPE:PRINCIPAL_NAME:IAM_ROLE, see the gsutil iam ch reference page.

Note: The gsutil iam ch command does not work with policies that contain conditions. To modify a policy that has conditions, use gsutil iam get to retrieve the policy for the relevant bucket, edit it locally, and then use gsutil iam set to re-apply it to the bucket.

Code samples

C++

For more information, see the Cloud Storage C++ API reference documentation.

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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::runtime_error(policy.status().message());

  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::runtime_error(updated.status().message());

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

C#

For more information, see the Cloud Storage C# API reference documentation.

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using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;
using System.Collections.Generic;

public class AddBucketIamMemberSample
{
    public Policy AddBucketIamMember(
        string bucketName = "your-unique-bucket-name",
        string role = "roles/storage.objectViewer",
        string member = "serviceAccount:[e-mail]")
    {
        var storage = StorageClient.Create();
        var policy = storage.GetBucketIamPolicy(bucketName, new GetBucketIamPolicyOptions
        {
            RequestedPolicyVersion = 3
        });
        // Set the policy schema version. For more information, please refer to https://cloud.google.com/iam/docs/policies#versions.
        policy.Version = 3;

        Policy.BindingsData bindingToAdd = new Policy.BindingsData
        {
            Role = role,
            Members = new List<string> { member }
        };

        policy.Bindings.Add(bindingToAdd);
        var bucketIamPolicy = storage.SetBucketIamPolicy(bucketName, policy);
        Console.WriteLine($"Added {member} with role {role} " + $"to {bucketName}");
        return bucketIamPolicy;
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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import (
	"context"
	"fmt"
	"io"
	"time"

	"cloud.google.com/go/iam"
	"cloud.google.com/go/storage"
)

// addBucketIAMMember adds the bucket IAM member to permission role.
func addBucketIAMMember(w io.Writer, bucketName string) error {
	// bucketName := "bucket-name"
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %v", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
	defer cancel()

	bucket := client.Bucket(bucketName)
	policy, err := bucket.IAM().Policy(ctx)
	if err != nil {
		return fmt.Errorf("Bucket(%q).IAM().Policy: %v", bucketName, err)
	}
	// Other valid prefixes are "serviceAccount:", "user:"
	// See the documentation for more values.
	// https://cloud.google.com/storage/docs/access-control/iam
	identity := "group:[e-mail]"
	var role iam.RoleName = "roles/storage.objectViewer"

	policy.Add(identity, role)
	if err := bucket.IAM().SetPolicy(ctx, policy); err != nil {
		return fmt.Errorf("Bucket(%q).IAM().SetPolicy: %v", bucketName, err)
	}
	// NOTE: It may be necessary to retry this operation if IAM policies are
	// being modified concurrently. SetPolicy will return an error if the policy
	// was modified since it was retrieved.
	fmt.Fprintf(w, "Added %v with role %v to %v\n", identity, role, bucketName)
	return nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

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import com.google.cloud.Binding;
import com.google.cloud.Policy;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class AddBucketIamMember {
  /** Example of adding a member to the Bucket-level IAM */
  public static void addBucketIamMember(String projectId, String bucketName) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // For more information please read:
    // https://cloud.google.com/storage/docs/access-control/iam
    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();

    Policy originalPolicy =
        storage.getIamPolicy(bucketName, Storage.BucketSourceOption.requestedPolicyVersion(3));

    String role = "roles/storage.objectViewer";
    String member = "group:[e-mail]";

    // getBindingsList() returns an ImmutableList and copying over to an ArrayList so it's mutable.
    List<Binding> bindings = new ArrayList(originalPolicy.getBindingsList());

    // Create a new binding using role and member
    Binding.Builder newMemberBindingBuilder = Binding.newBuilder();
    newMemberBindingBuilder.setRole(role).setMembers(Arrays.asList(member));
    bindings.add(newMemberBindingBuilder.build());

    // Update policy to add member
    Policy.Builder updatedPolicyBuilder = originalPolicy.toBuilder();
    updatedPolicyBuilder.setBindings(bindings).setVersion(3);
    Policy updatedPolicy = storage.setIamPolicy(bucketName, updatedPolicyBuilder.build());

    System.out.printf("Added %s with role %s to %s\n", member, role, bucketName);
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The role to grant
// const roleName = 'roles/storage.objectViewer';

// The members to grant the new role to
// const members = [
//   'user:[e-mail]',
//   'group:[e-mail]',
// ];

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function addBucketIamMember() {
  // Get a reference to a Google Cloud Storage bucket
  const bucket = storage.bucket(bucketName);

  // For more information please read:
  // https://cloud.google.com/storage/docs/access-control/iam
  const [policy] = await bucket.iam.getPolicy({requestedPolicyVersion: 3});

  // Adds the new roles to the bucket's IAM policy
  policy.bindings.push({
    role: roleName,
    members: members,
  });

  // Updates the bucket's IAM policy
  await bucket.iam.setPolicy(policy);

  console.log(
    `Added the following member(s) with role ${roleName} to ${bucketName}:`
  );

  members.forEach(member => {
    console.log(`  ${member}`);
  });
}

addBucketIamMember().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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use Google\Cloud\Storage\StorageClient;

/**
 * Adds a new member / role IAM pair to a given Cloud Storage bucket.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 * @param string $role The role to which the given member should be added.
 * @param string[] $members The member(s) to be added to the role.
 */
function add_bucket_iam_member($bucketName, $role, array $members)
{
    // $bucketName = 'my-bucket';
    // $role = 'roles/storage.objectViewer';
    // $members = ['group:[e-mail]'];

    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);

    $policy = $bucket->iam()->policy(['requestedPolicyVersion' => 3]);
    $policy['version'] = 3;

    $policy['bindings'][] = [
        'role' => $role,
        'members' => $members
    ];

    $bucket->iam()->setPolicy($policy);

    printf('Added the following member(s) to role %s for bucket %s' . PHP_EOL, $role, $bucketName);
    foreach ($members as $member) {
        printf('    %s' . PHP_EOL, $member);
    }
}

Python

For more information, see the Cloud Storage Python API reference documentation.

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from google.cloud import storage


def add_bucket_iam_member(bucket_name, role, member):
    """Add a new member to an IAM Policy"""
    # bucket_name = "your-bucket-name"
    # role = "IAM role, e.g., roles/storage.objectViewer"
    # member = "IAM identity, e.g., user: [e-mail]"

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)

    policy = bucket.get_iam_policy(requested_policy_version=3)

    policy.bindings.append({"role": role, "members": {member}})

    bucket.set_iam_policy(policy)

    print("Added {} with role {} to {}.".format(member, role, bucket_name))

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

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def add_bucket_iam_member bucket_name:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket = storage.bucket bucket_name

  role   = "roles/storage.objectViewer"
  member = "group:[e-mail]"

  bucket.policy requested_policy_version: 3 do |policy|
    policy.bindings.insert role: role, members: [member]
  end

  puts "Added #{member} with role #{role} to #{bucket_name}"
end

JSON

1. Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.

2. Create a .json file that contains the following information:

   {
     "bindings":[
       {
         "role": "IAM_ROLE",
         "members":[
           "PRINCIPAL_NAME"
         ]
       }
     ]
   }

   Where:

   • IAM_ROLE is the IAM role you are granting. For example, roles/storage.objectViewer.

   • PRINCIPAL_NAME is the name of the principal to which you are granting bucket access. For example, [e-mail].

     For more examples of how to format PRINCIPAL_NAME, see the principals section here.

3. Use cURL to call the JSON API with a PUT setIamPolicy request:

   curl -X PUT --data-binary @JSON_FILE_NAME.json \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     -H "Content-Type: application/json" \
     "https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/iam"

   Where:

   • JSON_FILE_NAME is the name of the file you created in Step 2.
   • OAUTH2_TOKEN is the access token you generated in Step 1.
   • BUCKET_NAME is the name of the bucket to which you want to give the principal access. For example, my-bucket.

Note: You should set the minimum permission possible that gives the principal the required access. For example, if a team member only needs to read objects stored in a bucket, select the Storage Object Viewer role. Similarly, if the team member needs full control of objects in the bucket (but not control of the bucket itself), select Storage Object Admin.

Viewing the IAM policy for a bucket

Console

1. In the Google Cloud Console, go to the Cloud Storage Browser page.
   

   Go to Browser

2. Click the Bucket overflow menu () associated with the bucket whose policy you want to view.

3. Choose Edit bucket permissions.

4. Expand the desired role to view the principals who have that role.

5. (Optional) Use the search bar to filter your results by role or principal.

   If you search by principal, your results display each role that the principal is granted.

gsutil

Use the gsutil iam get command:

gsutil iam get gs://BUCKET_NAME

Where BUCKET_NAME is the name of the bucket whose IAM policy you want to view. For example, my-bucket.

Code samples

C++

For more information, see the Cloud Storage C++ API reference documentation.

View on GitHub Feedback

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::runtime_error(policy.status().message());
  std::cout << "The IAM policy for bucket " << bucket_name << " is "
            << *policy << "\n";
}

C#

For more information, see the Cloud Storage C# API reference documentation.

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using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;

public class ViewBucketIamMembersSample
{
    public Policy ViewBucketIamMembers(string bucketName = "your-unique-bucket-name")
    {
        var storage = StorageClient.Create();
        var policy = storage.GetBucketIamPolicy(bucketName, new GetBucketIamPolicyOptions
        {
            RequestedPolicyVersion = 3
        });

        foreach (var binding in policy.Bindings)
        {
            Console.WriteLine($"Role: {binding.Role}");
            Console.WriteLine("Members:");
            foreach (var member in binding.Members)
            {
                Console.WriteLine($"{member}");
            }
        }
        return policy;
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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import (
	"context"
	"fmt"
	"io"
	"time"

	"cloud.google.com/go/iam"
	"cloud.google.com/go/storage"
)

// getBucketPolicy gets the bucket IAM policy.
func getBucketPolicy(w io.Writer, bucketName string) (*iam.Policy3, error) {
	// bucketName := "bucket-name"
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return nil, fmt.Errorf("storage.NewClient: %v", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
	defer cancel()

	policy, err := client.Bucket(bucketName).IAM().V3().Policy(ctx)
	if err != nil {
		return nil, fmt.Errorf("Bucket(%q).IAM().V3().Policy: %v", bucketName, err)
	}
	for _, binding := range policy.Bindings {
		fmt.Fprintf(w, "%q: %q (condition: %v)\n", binding.Role, binding.Members, binding.Condition)
	}
	return policy, nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

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import com.google.cloud.Binding;
import com.google.cloud.Policy;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;

public class ListBucketIamMembers {
  public static void listBucketIamMembers(String projectId, String bucketName) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // For more information please read:
    // https://cloud.google.com/storage/docs/access-control/iam
    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();

    Policy policy =
        storage.getIamPolicy(bucketName, Storage.BucketSourceOption.requestedPolicyVersion(3));

    // Print binding information
    for (Binding binding : policy.getBindingsList()) {
      System.out.printf("Role: %s Members: %s\n", binding.getRole(), binding.getMembers());

      // Print condition if one is set
      boolean bindingIsConditional = binding.getCondition() != null;
      if (bindingIsConditional) {
        System.out.printf("Condition Title: %s\n", binding.getCondition().getTitle());
        System.out.printf("Condition Description: %s\n", binding.getCondition().getDescription());
        System.out.printf("Condition Expression: %s\n", binding.getCondition().getExpression());
      }
    }
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function viewBucketIamMembers() {
  // For more information please read:
  // https://cloud.google.com/storage/docs/access-control/iam
  const results = await storage
    .bucket(bucketName)
    .iam.getPolicy({requestedPolicyVersion: 3});

  const bindings = results[0].bindings;

  console.log(`Bindings for bucket ${bucketName}:`);
  for (const binding of bindings) {
    console.log(`  Role: ${binding.role}`);
    console.log('  Members:');

    const members = binding.members;
    for (const member of members) {
      console.log(`    ${member}`);
    }

    const condition = binding.condition;
    if (condition) {
      console.log('  Condiiton:');
      console.log(`    Title: ${condition.title}`);
      console.log(`    Description: ${condition.description}`);
      console.log(`    Expression: ${condition.expression}`);
    }
  }
}

viewBucketIamMembers().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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use Google\Cloud\Storage\StorageClient;

/**
 * View Bucket IAM members for a given Cloud Storage bucket.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 */
function view_bucket_iam_members($bucketName)
{
    // $bucketName = 'my-bucket';

    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);

    $policy = $bucket->iam()->policy(['requestedPolicyVersion' => 3]);

    printf('Printing Bucket IAM members for Bucket: %s' . PHP_EOL, $bucketName);
    printf(PHP_EOL);

    foreach ($policy['bindings'] as $binding) {
        printf('Role: %s' . PHP_EOL, $binding['role']);
        printf('Members:' . PHP_EOL);
        foreach ($binding['members'] as $member) {
            printf('  %s' . PHP_EOL, $member);
        }

        if (isset($binding['condition'])) {
            $condition = $binding['condition'];
            printf('  with condition:' . PHP_EOL);
            printf('    Title: %s' . PHP_EOL, $condition['title']);
            printf('    Description: %s' . PHP_EOL, $condition['description']);
            printf('    Expression: %s' . PHP_EOL, $condition['expression']);
        }
        printf(PHP_EOL);
    }
}

Python

For more information, see the Cloud Storage Python API reference documentation.

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from google.cloud import storage


def view_bucket_iam_members(bucket_name):
    """View IAM Policy for a bucket"""
    # bucket_name = "your-bucket-name"

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)

    policy = bucket.get_iam_policy(requested_policy_version=3)

    for binding in policy.bindings:
        print("Role: {}, Members: {}".format(binding["role"], binding["members"]))

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

View on GitHub Feedback

def view_bucket_iam_members bucket_name:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket = storage.bucket bucket_name

  policy = bucket.policy requested_policy_version: 3
  policy.bindings.each do |binding|
    puts "Role: #{binding.role}"
    puts "Members: #{binding.members}"

    # if a conditional binding exists print the condition.
    if binding.condition
      puts "Condition Title: #{binding.condition.title}"
      puts "Condition Description: #{binding.condition.description}"
      puts "Condition Expression: #{binding.condition.expression}"
    end
  end
end

JSON

1. Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.

2. Use cURL to call the JSON API with a GET getIamPolicy request:

   curl -X GET \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     "https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/iam"

   Where:

   • OAUTH2_TOKEN is the access token you generated in Step 1.
   • BUCKET_NAME is the name of the bucket whose IAM policy you want to view. For example, my-bucket.

Note: Some roles may not appear in the bucket permissions window. If you grant roles at the project level, they do not appear in the bucket permission window, even when users with that role have access to your bucket. To view these project-level permissions, go to the IAM & Admin screen.

Removing a principal from a bucket-level policy

Console

1. In the Google Cloud Console, go to the Cloud Storage Browser page.
   

   Go to Browser

2. Click the Bucket overflow menu () associated with the bucket from which you want to remove a principal's role.

3. Choose Edit bucket permissions.

4. Expand the role that contains the principal you are removing.

5. Click on the trash icon.

6. In the overlay window that appears, click Remove.

To learn how to get detailed error information about failed operations in the Cloud Storage browser, see Troubleshooting.

gsutil

Use the gsutil iam ch command with a -d flag:

gsutil iam ch -d PRINCIPAL_TYPE:PRINCIPAL_NAME gs://BUCKET_NAME

Where:

• PRINCIPAL_TYPE is the type of the principal you are removing from the policy. For example, user.
• PRINCIPAL_NAME is the name of the principal you are removing from the policy. For example, [e-mail].
• BUCKET_NAME is the name of the bucket from which you are removing access. For example, my-bucket.

For more examples of how to format PRINCIPAL_TYPE:PRINCIPAL_NAME, see the gsutil iam ch reference page.

Note: The gsutil iam ch command does not work with policies that contain conditions. To modify a policy that has conditions, use gsutil iam get to retrieve the policy for the relevant bucket, edit it locally, and then use gsutil iam set to re-apply it to the bucket.

Code samples

C++

For more information, see the Cloud Storage C++ API reference documentation.

View on GitHub Feedback

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::runtime_error(policy.status().message());

  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::runtime_error(updated.status().message());

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

C#

For more information, see the Cloud Storage C# API reference documentation.

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using Google.Cloud.Storage.V1;
using System;
using System.Linq;

public class RemoveBucketIamMemberSample
{
    public void RemoveBucketIamMember(
        string bucketName = "your-unique-bucket-name",
        string role = "roles/storage.objectViewer",
        string member = "serviceAccount:[e-mail]")
    {
        var storage = StorageClient.Create();
        var policy = storage.GetBucketIamPolicy(bucketName, new GetBucketIamPolicyOptions
        {
            RequestedPolicyVersion = 3
        });
        // Set the policy schema version. For more information, please refer to https://cloud.google.com/iam/docs/policies#versions.
        policy.Version = 3;

        foreach (var binding in policy.Bindings.Where(c => c.Role == role).ToList())
        {
            // Remove the role/member combo from the IAM policy.
            binding.Members = binding.Members.Where(m => m != member).ToList();
            // Remove role if it contains no members.
            if (binding.Members.Count == 0)
            {
                policy.Bindings.Remove(binding);
            }
        }
        // Set the modified IAM policy to be the current IAM policy.
        storage.SetBucketIamPolicy(bucketName, policy);
        Console.WriteLine($"Removed {member} with role {role} from {bucketName}");
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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import (
	"context"
	"fmt"
	"io"
	"time"

	"cloud.google.com/go/iam"
	"cloud.google.com/go/storage"
)

// removeBucketIAMMember removes the bucket IAM member.
func removeBucketIAMMember(w io.Writer, bucketName string) error {
	// bucketName := "bucket-name"
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %v", err)
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
	defer cancel()

	bucket := client.Bucket(bucketName)
	policy, err := bucket.IAM().Policy(ctx)
	if err != nil {
		return fmt.Errorf("Bucket(%q).IAM().Policy: %v", bucketName, err)
	}
	// Other valid prefixes are "serviceAccount:", "user:"
	// See the documentation for more values.
	// https://cloud.google.com/storage/docs/access-control/iam
	// member string, role iam.RoleName
	identity := "group:[e-mail]"
	var role iam.RoleName = "roles/storage.objectViewer"

	policy.Remove(identity, role)
	if err := bucket.IAM().SetPolicy(ctx, policy); err != nil {
		return fmt.Errorf("Bucket(%q).IAM().SetPolicy: %v", bucketName, err)
	}
	// NOTE: It may be necessary to retry this operation if IAM policies are
	// being modified concurrently. SetPolicy will return an error if the policy
	// was modified since it was retrieved.
	fmt.Fprintf(w, "Removed %v with role %v from %v\n", identity, role, bucketName)
	return nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

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import com.google.cloud.Binding;
import com.google.cloud.Policy;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.util.ArrayList;
import java.util.List;

public class RemoveBucketIamMember {
  public static void removeBucketIamMember(String projectId, String bucketName) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // For more information please read:
    // https://cloud.google.com/storage/docs/access-control/iam
    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();

    Policy originalPolicy =
        storage.getIamPolicy(bucketName, Storage.BucketSourceOption.requestedPolicyVersion(3));

    String role = "roles/storage.objectViewer";
    String member = "group:[e-mail]";

    // getBindingsList() returns an ImmutableList and copying over to an ArrayList so it's mutable.
    List<Binding> bindings = new ArrayList(originalPolicy.getBindingsList());

    // Remove role-member binding without a condition.
    for (int index = 0; index < bindings.size(); index++) {
      Binding binding = bindings.get(index);
      boolean foundRole = binding.getRole().equals(role);
      boolean foundMember = binding.getMembers().contains(member);
      boolean bindingIsNotConditional = binding.getCondition() == null;

      if (foundRole && foundMember && bindingIsNotConditional) {
        bindings.set(index, binding.toBuilder().removeMembers(member).build());
        break;
      }
    }

    // Update policy to remove member
    Policy.Builder updatedPolicyBuilder = originalPolicy.toBuilder();
    updatedPolicyBuilder.setBindings(bindings).setVersion(3);
    Policy updatedPolicy = storage.setIamPolicy(bucketName, updatedPolicyBuilder.build());

    System.out.printf("Removed %s with role %s from %s\n", member, role, bucketName);
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The role to revoke
// const roleName = 'roles/storage.objectViewer';

// The members to revoke the roles from
// const members = [
//   'user:[e-mail]',
//   'group:[e-mail]',
// ];

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function removeBucketIamMember() {
  // Get a reference to a Google Cloud Storage bucket
  const bucket = storage.bucket(bucketName);

  // For more information please read:
  // https://cloud.google.com/storage/docs/access-control/iam
  const [policy] = await bucket.iam.getPolicy({requestedPolicyVersion: 3});

  // Finds and updates the appropriate role-member group, without a condition.
  const index = policy.bindings.findIndex(
    binding => binding.role === roleName && !binding.condition
  );

  const role = policy.bindings[index];
  if (role) {
    role.members = role.members.filter(
      member => members.indexOf(member) === -1
    );

    // Updates the policy object with the new (or empty) role-member group
    if (role.members.length === 0) {
      policy.bindings.splice(index, 1);
    } else {
      policy.bindings.index = role;
    }

    // Updates the bucket's IAM policy
    await bucket.iam.setPolicy(policy);
  } else {
    // No matching role-member group(s) were found
    throw new Error('No matching role-member group(s) found.');
  }

  console.log(
    `Removed the following member(s) with role ${roleName} from ${bucketName}:`
  );
  members.forEach(member => {
    console.log(`  ${member}`);
  });
}

removeBucketIamMember().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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use Google\Cloud\Storage\StorageClient;

/**
 * Removes a member / role IAM pair from a given Cloud Storage bucket.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 * @param string $role The role from which the specified member should be removed.
 * @param string $member The member to be removed from the specified role.
 */
function remove_bucket_iam_member($bucketName, $role, $member)
{
    // $bucketName = 'my-bucket';
    // $role = 'roles/storage.objectViewer';
    // $member = 'group:[e-mail]';

    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $iam = $bucket->iam();
    $policy = $iam->policy(['requestedPolicyVersion' => 3]);
    $policy['version'] = 3;

    foreach ($policy['bindings'] as $i => $binding) {
        // This example only removes member from bindings without a condition.
        if ($binding['role'] == $role && !isset($binding['condition'])) {
            $key = array_search($member, $binding['members']);
            if ($key !== false) {
                unset($binding['members'][$key]);

                // If the last member is removed from the binding, clean up the
                // binding.
                if (count($binding['members']) == 0) {
                    unset($policy['bindings'][$i]);
                    // Ensure array keys are sequential, otherwise JSON encodes
                    // the array as an object, which fails when calling the API.
                    $policy['bindings'] = array_values($policy['bindings']);
                } else {
                    // Ensure array keys are sequential, otherwise JSON encodes
                    // the array as an object, which fails when calling the API.
                    $binding['members'] = array_values($binding['members']);
                    $policy['bindings'][$i] = $binding;
                }

                $iam->setPolicy($policy);
                printf('User %s removed from role %s for bucket %s' . PHP_EOL, $member, $role, $bucketName);
                return;
            }
        }
    }

    throw new \RuntimeException('No matching role-member group(s) found.');
}

Python

For more information, see the Cloud Storage Python API reference documentation.

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from google.cloud import storage


def remove_bucket_iam_member(bucket_name, role, member):
    """Remove member from bucket IAM Policy"""
    # bucket_name = "your-bucket-name"
    # role = "IAM role, e.g. roles/storage.objectViewer"
    # member = "IAM identity, e.g. user: [e-mail]"

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)

    policy = bucket.get_iam_policy(requested_policy_version=3)

    for binding in policy.bindings:
        print(binding)
        if binding["role"] == role and binding.get("condition") is None:
            binding["members"].discard(member)

    bucket.set_iam_policy(policy)

    print("Removed {} with role {} from {}.".format(member, role, bucket_name))

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

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def remove_bucket_iam_member bucket_name:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  # For more information please read: https://cloud.google.com/storage/docs/access-control/iam

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket = storage.bucket bucket_name

  role   = "roles/storage.objectViewer"
  member = "group:[e-mail]"

  bucket.policy requested_policy_version: 3 do |policy|
    policy.bindings.each do |binding|
      if binding.role == role && binding.condition.nil?
        binding.members.delete member
      end
    end
  end

  puts "Removed #{member} with role #{role} from #{bucket_name}"
end

JSON

1. Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.

2. Get the existing policy applied to your project. To do so, use cURL to call the JSON API with a GET getIamPolicy request:

   curl -X GET \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     "https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/iam"

   Where:

   • OAUTH2_TOKEN is the access token you generated in Step 1.
   • BUCKET_NAME is the name of the bucket whose IAM policy you want to view. For example, my-bucket.

3. Create a .json file that contains the policy you retrieved in the previous step.

4. Edit the .json file to remove the principal from the policy.

5. Use cURL to call the JSON API with a PUT setIamPolicy request:

   curl -X PUT --data-binary @JSON_FILE_NAME.json \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     -H "Content-Type: application/json" \
     "https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/iam"

   Where:

   • JSON_FILE_NAME is the name of the file you created in Step 3.
   • OAUTH2_TOKEN is the access token you generated in Step 1.
   • BUCKET_NAME is the name of the bucket from which you want to remove access. For example, my-bucket.

Important: It typically takes about a minute for revoking access to take effect. In some cases it may take longer. If you remove a user's access, this change is immediately reflected in the metadata; however, the user may still have access to the object for a short period of time.

Using IAM Conditions on buckets

The following sections show you how to add and remove IAM Conditions on your buckets. To view the IAM Conditions for your bucket, see Viewing the IAM policy for a bucket. For more information about using IAM Conditions with Cloud Storage, see Conditions.

You must enable uniform bucket-level access on the bucket before adding conditions.

Setting a new condition on a bucket

Console

1. In the Google Cloud Console, go to the Cloud Storage Browser page.
   

   Go to Browser

2. Click the Bucket overflow menu () on the far right of the row associated with the bucket.

3. Choose Edit bucket permissions.

4. Click Add principals.

5. For New principals, fill out the principals to which you want to grant access to your bucket.

6. For each role to which you want to apply a condition:

   1. Select a Role to grant the principals.

   2. Click Add condition to open the Edit condition form.

   3. Fill out the Title of the condition. The Description field is optional.

   4. Use the Condition Builder to build your condition visually, or use the Condition Editor tab to enter the CEL expression.

   5. Click Save to return to the Add principals form. To add multiple roles, click Add another role.

7. Click Save.

To learn how to get detailed error information about failed operations in the Cloud Storage browser, see Troubleshooting.

gsutil

Note: gsutil must be at version 4.38 or higher to use conditions.

1. Use the gsutil iam command to save the bucket's IAM policy to a temporary JSON file.

   gsutil iam get gs://BUCKET_NAME > /tmp/policy.json

   Where BUCKET_NAME is the name of the bucket whose IAM policy you want to retrieve. For example, my-bucket.

2. Edit the /tmp/policy.json file in a text editor to add new conditions to the bindings in the IAM policy:

   {
     "version": VERSION,
     "bindings": [
       {
         "role": "IAM_ROLE",
         "members": [
           "PRINCIPAL_NAME"
         ],
         "condition": {
           "title": "TITLE",
           "description": "DESCRIPTION",
           "expression": "EXPRESSION"
         }
     ],
     "etag": "ETAG"
   }

   Where:

   • VERSION is the IAM policy version, which is required to be 3 for buckets with IAM Conditions.
   • IAM ROLE is the role to which the condition applies. For example, roles/storage.objectViewer.
   • PRINCIPAL_NAME is the principal to which the condition applies. For example, [e-mail].
   • TITLE is the title of the condition. For example, expires in 2019.
   • DESCRIPTION is an optional description of the condition. For example, Permission revoked on New Year's.
   • EXPRESSION is an attribute-based logic expression. For example, request.time < timestamp(\"2019-01-01T00:00:00Z\"). For more examples of expressions, see the Conditions attribute reference. Note that Cloud Storage only supports the date/time, resource type, and resource name attributes.

   Do not modify ETAG.

3. Use gsutil iam to set the modified IAM policy on the bucket.

   gsutil iam set /tmp/policy.json gs://BUCKET_NAME

Note: The gsutil iam ch command does not work with policies that contain conditions.

Code samples

C++

For more information, see the Cloud Storage C++ API reference documentation.

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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,
   std::string const& condition_title,
   std::string const& condition_description,
   std::string const& condition_expression) {
  auto policy = client.GetNativeBucketIamPolicy(
      bucket_name, gcs::RequestedPolicyVersion(3));
  if (!policy) throw std::runtime_error(policy.status().message());

  policy->set_version(3);
  policy->bindings().emplace_back(gcs::NativeIamBinding(
      role, {member},
      gcs::NativeExpression(condition_expression, condition_title,
                            condition_description)));

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

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

  std::cout << "Added member " << member << " with role " << role << " to "
            << bucket_name << ":\n";
  std::cout << "with condition:\n"
            << "\t Title: " << condition_title << "\n"
            << "\t Description: " << condition_description << "\n"
            << "\t Expression: " << condition_expression << "\n";
}

C#

For more information, see the Cloud Storage C# API reference documentation.

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using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;
using System.Collections.Generic;

public class AddBucketConditionalIamBindingSample
{
    /// <summary>
    /// Adds a conditional Iam policy to a bucket.
    /// </summary>
    /// <param name="bucketName">The name of the bucket.</param>
    /// <param name="role">The role that members may assume.</param>
    /// <param name="member">The identifier of the member who may assume the provided role.</param>
    /// <param name="title">Title for the expression.</param>
    /// <param name="description">Description of the expression.</param>
    /// <param name="expression">Describes the conditions that need to be met for the policy to be applied.
    /// It's represented as a string using Common Expression Language syntax.</param>
    public Policy AddBucketConditionalIamBinding(
        string bucketName = "your-unique-bucket-name",
        string role = "roles/storage.objectViewer",
        string member = "serviceAccount:[e-mail]",
        string title = "title",
        string description = "description",
        string expression = "resource.name.startsWith(\"projects/_/buckets/bucket-name/objects/prefix-a-\")")
    {
        var storage = StorageClient.Create();
        var policy = storage.GetBucketIamPolicy(bucketName, new GetBucketIamPolicyOptions
        {
            RequestedPolicyVersion = 3
        });
        // Set the policy schema version. For more information, please refer to https://cloud.google.com/iam/docs/policies#versions.
        policy.Version = 3;
        Policy.BindingsData bindingToAdd = new Policy.BindingsData
        {
            Role = role,
            Members = new List<string> { member },
            Condition = new Expr
            {
                Title = title,
                Description = description,
                Expression = expression
            }
        };

        policy.Bindings.Add(bindingToAdd);

        var bucketIamPolicy = storage.SetBucketIamPolicy(bucketName, policy);
        Console.WriteLine($"Added {member} with role {role} " + $"to {bucketName}");
        return bucketIamPolicy;
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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ctx := context.Background()

ctx, cancel := context.WithTimeout(ctx, time.Second*10)
defer cancel()
bucket := c.Bucket(bucketName)
policy, err := bucket.IAM().V3().Policy(ctx)
if err != nil {
	return err
}

policy.Bindings = append(policy.Bindings, &iampb.Binding{
	Role:    role,
	Members: []string{member},
	Condition: &expr.Expr{
		Title:       title,
		Description: description,
		Expression:  expression,
	},
})

if err := bucket.IAM().V3().SetPolicy(ctx, policy); err != nil {
	return err
}
// NOTE: It may be necessary to retry this operation if IAM policies are
// being modified concurrently. SetPolicy will return an error if the policy
// was modified since it was retrieved.

Java

For more information, see the Cloud Storage Java API reference documentation.

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import com.google.cloud.Binding;
import com.google.cloud.Condition;
import com.google.cloud.Policy;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class AddBucketIamConditionalBinding {
  /** Example of adding a conditional binding to the Bucket-level IAM */
  public static void addBucketIamConditionalBinding(String projectId, String bucketName) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // For more information please read:
    // https://cloud.google.com/storage/docs/access-control/iam
    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();

    Policy originalPolicy =
        storage.getIamPolicy(bucketName, Storage.BucketSourceOption.requestedPolicyVersion(3));

    String role = "roles/storage.objectViewer";
    String member = "group:[e-mail]";

    // getBindingsList() returns an ImmutableList and copying over to an ArrayList so it's mutable.
    List<Binding> bindings = new ArrayList(originalPolicy.getBindingsList());

    // Create a condition
    String conditionTitle = "Title";
    String conditionDescription = "Description";
    String conditionExpression =
        "resource.name.startsWith(\"projects/_/buckets/bucket-name/objects/prefix-a-\")";
    Condition.Builder conditionBuilder = Condition.newBuilder();
    conditionBuilder.setTitle(conditionTitle);
    conditionBuilder.setDescription(conditionDescription);
    conditionBuilder.setExpression(conditionExpression);

    // Add condition to a binding
    Binding.Builder newBindingBuilder =
        Binding.newBuilder()
            .setRole(role)
            .setMembers(Arrays.asList(member))
            .setCondition(conditionBuilder.build());
    bindings.add(newBindingBuilder.build());

    // Update policy with new conditional binding
    Policy.Builder updatedPolicyBuilder = originalPolicy.toBuilder();
    updatedPolicyBuilder.setBindings(bindings).setVersion(3);
    Policy updatedPolicy = storage.setIamPolicy(bucketName, updatedPolicyBuilder.build());

    System.out.printf(
        "Added %s with role %s to %s with condition %s %s %s\n",
        member, role, bucketName, conditionTitle, conditionDescription, conditionExpression);
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The role to grant
// const roleName = 'roles/storage.objectViewer';

// The members to grant the new role to
// const members = [
//   'user:[e-mail]',
//   'group:[e-mail]',
// ];

// Create a condition
// const title = 'Title';
// const description = 'Description';
// const expression = 'resource.name.startsWith(\"projects/_/buckets/bucket-name/objects/prefix-a-\")';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function addBucketConditionalBinding() {
  // Get a reference to a Google Cloud Storage bucket
  const bucket = storage.bucket(bucketName);

  // Gets and updates the bucket's IAM policy
  const [policy] = await bucket.iam.getPolicy({requestedPolicyVersion: 3});

  // Set the policy's version to 3 to use condition in bindings.
  policy.version = 3;

  // Adds the new roles to the bucket's IAM policy
  policy.bindings.push({
    role: roleName,
    members: members,
    condition: {
      title: title,
      description: description,
      expression: expression,
    },
  });

  // Updates the bucket's IAM policy
  await bucket.iam.setPolicy(policy);

  console.log(
    `Added the following member(s) with role ${roleName} to ${bucketName}:`
  );

  members.forEach(member => {
    console.log(`  ${member}`);
  });

  console.log('with condition:');
  console.log(`  Title: ${title}`);
  console.log(`  Description: ${description}`);
  console.log(`  Expression: ${expression}`);
}

addBucketConditionalBinding().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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use Google\Cloud\Storage\StorageClient;

/**
 * Adds a conditional IAM binding to a bucket's IAM policy.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 * @param string $role The role that will be given to members in this binding.
 * @param string[] $members The member(s) associated with this binding.
 * @param string $title The title of the condition.
 * @param string $description The description of the condition.
 * @param string $expression The condition specified in CEL expression language.
 *
 * To see how to express a condition in CEL, visit:
 * @see https://cloud.google.com/storage/docs/access-control/iam#conditions.
 */
function add_bucket_conditional_iam_binding($bucketName, $role, array $members, $title, $description, $expression)
{
    // $bucketName = 'my-bucket';
    // $role = 'roles/storage.objectViewer';
    // $members = ['group:[e-mail]'];
    // $title = 'Title';
    // $description = 'Condition Description';
    // $expression = 'resource.name.startsWith("projects/_/buckets/bucket-name/objects/prefix-a-")';

    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);

    $policy = $bucket->iam()->policy(['requestedPolicyVersion' => 3]);

    $policy['version'] = 3;

    $policy['bindings'][] = [
        'role' => $role,
        'members' => $members,
        'condition' => [
            'title' => $title,
            'description' => $description,
            'expression' => $expression,
        ],
    ];

    $bucket->iam()->setPolicy($policy);

    printf('Added the following member(s) with role %s to %s:' . PHP_EOL, $role, $bucketName);
    foreach ($members as $member) {
        printf('    %s' . PHP_EOL, $member);
    }
    printf('with condition:' . PHP_EOL);
    printf('    Title: %s' . PHP_EOL, $title);
    printf('    Description: %s' . PHP_EOL, $description);
    printf('    Expression: %s' . PHP_EOL, $expression);
}

Python

For more information, see the Cloud Storage Python API reference documentation.

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from google.cloud import storage


def add_bucket_conditional_iam_binding(
    bucket_name, role, title, description, expression, members
):
    """Add a conditional IAM binding to a bucket's IAM policy."""
    # bucket_name = "your-bucket-name"
    # role = "IAM role, e.g. roles/storage.objectViewer"
    # members = {"IAM identity, e.g. user: [e-mail]}"
    # title = "Condition title."
    # description = "Condition description."
    # expression = "Condition expression."

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)

    policy = bucket.get_iam_policy(requested_policy_version=3)

    # Set the policy's version to 3 to use condition in bindings.
    policy.version = 3

    policy.bindings.append(
        {
            "role": role,
            "members": members,
            "condition": {
                "title": title,
                "description": description,
                "expression": expression,
            },
        }
    )

    bucket.set_iam_policy(policy)

    print("Added the following member(s) with role {} to {}:".format(role, bucket_name))

    for member in members:
        print("    {}".format(member))

    print("with condition:")
    print("    Title: {}".format(title))
    print("    Description: {}".format(description))
    print("    Expression: {}".format(expression))

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

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def add_bucket_conditional_iam_binding bucket_name:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket = storage.bucket bucket_name

  role        = "roles/storage.objectViewer"
  member      = "group:[e-mail]"
  title       = "Title"
  description = "Description"
  expression  = "resource.name.startsWith(\"projects/_/buckets/bucket-name/objects/prefix-a-\")"

  bucket.policy requested_policy_version: 3 do |policy|
    policy.version = 3
    policy.bindings.insert(
      role:      role,
      members:   member,
      condition: {
        title:       title,
        description: description,
        expression:  expression
      }
    )
  end

  puts "Added #{member} with role #{role} to #{bucket_name} with condition #{title} #{description} #{expression}"
end

JSON

1. Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.

2. Use a GET getIamPolicy request to save the bucket's IAM policy to a temporary JSON file:

   curl \
   'https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/iam' \
   --header 'Authorization: Bearer OAUTH2_TOKEN' > /tmp/policy.json

   Where:

   • OAUTH2_TOKEN is the access token you generated in Step 1.

3. Edit the /tmp/policy.json file in a text editor to add new conditions to the bindings in the IAM policy:

   {
         "version": VERSION,
         "bindings": [
           {
             "role": "IAM_ROLE",
             "members": [
               "PRINCIPAL_NAME"
             ],
             "condition": {
               "title": "TITLE",
               "description": "DESCRIPTION",
               "expression": "EXPRESSION"
             }
         ],
         "etag": "ETAG"
    }

   Where:

   • VERSION is the IAM policy version, which is required to be 3 for buckets with IAM Conditions.
   • IAM_ROLE is the role to which the condition applies. For example, roles/storage.objectViewer.
   • PRINCIPAL_NAME is the principal to which the condition applies. For example, [e-mail].
   • TITLE is the title of the condition. For example, expires in 2019.
   • DESCRIPTION is an optional description of the condition. For example, Permission revoked on New Year's.

   • EXPRESSION is an attribute-based logic expression. For example, request.time < timestamp(\"2019-01-01T00:00:00Z\"). For more examples of expressions, see the Conditions attribute reference. Note that Cloud Storage only supports the date/time, resource type, and resource name attributes.

     Do not modify ETAG.

4. Use a PUT setIamPolicy request to set the modified IAM policy on the bucket:

   curl -X PUT --data-binary @/tmp/policy.json \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     -H "Content-Type: application/json" \
     "https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/iam"

   Where:

   • OAUTH2_TOKEN is the access token you generated in Step 1.

Removing a condition from a bucket

Console

1. In the Google Cloud Console, go to the Cloud Storage Browser page.
   

   Go to Browser

2. Click the Bucket overflow menu () on the far right of the row associated with the bucket.

3. Choose Edit bucket permissions.

4. Expand the role that contains the condition you are removing.

5. Click the Edit menu () for the principal associated with the condition.

6. In the Edit permissions overlay that appears, click on the name of the condition you want to delete.

7. In the Edit condition overlay that appears, click Delete, then Confirm.

8. Click Save.

To learn how to get detailed error information about failed operations in the Cloud Storage browser, see Troubleshooting.

gsutil

Note: gsutil must be at version 4.38 or higher to use conditions.

1. Use the gsutil iam command to save the bucket's IAM policy to a temporary JSON file.

   gsutil iam get gs://BUCKET_NAME > /tmp/policy.json

2. Edit the /tmp/policy.json file in a text editor to remove conditions from the IAM policy.

3. Use gsutil iam to set the modified IAM policy on the bucket.

   gsutil iam set /tmp/policy.json gs://BUCKET_NAME

Note: The gsutil iam ch command does not work with policies that contain conditions.

Code samples

C++

For more information, see the Cloud Storage C++ API reference documentation.

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

  policy->set_version(3);
  auto& bindings = policy->bindings();
  auto e = std::remove_if(
      bindings.begin(), bindings.end(),
      [role, condition_title, condition_description,
       condition_expression](gcs::NativeIamBinding b) {
        return (b.role() == role && b.has_condition() &&
                b.condition().title() == condition_title &&
                b.condition().description() == condition_description &&
                b.condition().expression() == condition_expression);
      });
  if (e == bindings.end()) {
    std::cout << "No matching binding group found.\n";
    return;
  }
  bindings.erase(e);
  auto updated = client.SetNativeBucketIamPolicy(bucket_name, *policy);
  if (!updated) throw std::runtime_error(updated.status().message());

  std::cout << "Conditional binding was removed.\n";
}

C#

For more information, see the Cloud Storage C# API reference documentation.

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using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;
using System.Linq;

public class RemoveBucketConditionalIamBindingSample
{
    public Policy RemoveBucketConditionalIamBinding(
        string bucketName = "your-unique-bucket-name",
        string role = "roles/storage.objectViewer",
        string title = "title",
        string description = "description",
        string expression = "resource.name.startsWith(\"projects/_/buckets/bucket-name/objects/prefix-a-\")")
    {
        var storage = StorageClient.Create();
        var policy = storage.GetBucketIamPolicy(bucketName, new GetBucketIamPolicyOptions
        {
            RequestedPolicyVersion = 3
        });
        // Set the policy schema version. For more information, please refer to https://cloud.google.com/iam/docs/policies#versions.
        policy.Version = 3;

        var bindingsToRemove = policy.Bindings.Where(binding => binding.Role == role
              && binding.Condition != null
              && binding.Condition.Title == title
              && binding.Condition.Description == description
              && binding.Condition.Expression == expression).ToList();
        if (bindingsToRemove.Count() > 0)
        {
            foreach (var binding in bindingsToRemove)
            {
                policy.Bindings.Remove(binding);
            }
            // Set the modified IAM policy to be the current IAM policy.
            policy = storage.SetBucketIamPolicy(bucketName, policy);
            Console.WriteLine("Conditional Binding was removed.");
        }
        else
        {
            Console.WriteLine("No matching conditional binding found.");
        }
        return policy;
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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ctx := context.Background()

ctx, cancel := context.WithTimeout(ctx, time.Second*10)
defer cancel()
bucket := c.Bucket(bucketName)
policy, err := bucket.IAM().V3().Policy(ctx)
if err != nil {
	return err
}

// Find the index of the binding matching inputs
i := -1
for j, binding := range policy.Bindings {
	if binding.Role == role && binding.Condition != nil {
		condition := binding.Condition
		if condition.Title == title &&
			condition.Description == description &&
			condition.Expression == expression {
			i = j
		}
	}
}

if i == -1 {
	return errors.New("No matching binding group found.")
}

// Get a slice of the bindings, removing the binding at index i
policy.Bindings = append(policy.Bindings[:i], policy.Bindings[i+1:]...)

if err := bucket.IAM().V3().SetPolicy(ctx, policy); err != nil {
	return err
}
// NOTE: It may be necessary to retry this operation if IAM policies are
// being modified concurrently. SetPolicy will return an error if the policy
// was modified since it was retrieved.

Java

For more information, see the Cloud Storage Java API reference documentation.

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import com.google.cloud.Binding;
import com.google.cloud.Condition;
import com.google.cloud.Policy;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class RemoveBucketIamConditionalBinding {
  /** Example of removing a conditional binding to the Bucket-level IAM */
  public static void removeBucketIamConditionalBinding(String projectId, String bucketName) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // For more information please read:
    // https://cloud.google.com/storage/docs/access-control/iam
    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();

    Policy originalPolicy =
        storage.getIamPolicy(bucketName, Storage.BucketSourceOption.requestedPolicyVersion(3));

    String role = "roles/storage.objectViewer";

    // getBindingsList() returns an ImmutableList and copying over to an ArrayList so it's mutable.
    List<Binding> bindings = new ArrayList(originalPolicy.getBindingsList());

    // Create a condition to compare against
    Condition.Builder conditionBuilder = Condition.newBuilder();
    conditionBuilder.setTitle("Title");
    conditionBuilder.setDescription("Description");
    conditionBuilder.setExpression(
        "resource.name.startsWith(\"projects/_/buckets/bucket-name/objects/prefix-a-\")");

    Iterator iterator = bindings.iterator();
    while (iterator.hasNext()) {
      Binding binding = (Binding) iterator.next();
      boolean foundRole = binding.getRole().equals(role);
      boolean conditionsEqual = conditionBuilder.build().equals(binding.getCondition());

      // Remove condition when the role and condition are equal
      if (foundRole && conditionsEqual) {
        iterator.remove();
        break;
      }
    }

    // Update policy to remove conditional binding
    Policy.Builder updatedPolicyBuilder = originalPolicy.toBuilder();
    updatedPolicyBuilder.setBindings(bindings).setVersion(3);
    Policy updatedPolicy = storage.setIamPolicy(bucketName, updatedPolicyBuilder.build());

    System.out.println("Conditional Binding was removed.");
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The role to grant
// const roleName = 'roles/storage.objectViewer';

// The members to grant the new role to
// const members = [
//   'user:[e-mail]',
//   'group:[e-mail]',
// ];

// Create a condition
// const title = 'Title';
// const description = 'Description';
// const expression = 'resource.name.startsWith(\"projects/_/buckets/bucket-name/objects/prefix-a-\")';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function removeBucketConditionalBinding() {
  // Get a reference to a Google Cloud Storage bucket
  const bucket = storage.bucket(bucketName);

  // Gets and updates the bucket's IAM policy
  const [policy] = await bucket.iam.getPolicy({requestedPolicyVersion: 3});

  // Set the policy's version to 3 to use condition in bindings.
  policy.version = 3;

  // Finds and removes the appropriate role-member group with specific condition.
  const index = policy.bindings.findIndex(
    binding =>
      binding.role === roleName &&
      binding.condition &&
      binding.condition.title === title &&
      binding.condition.description === description &&
      binding.condition.expression === expression
  );

  const binding = policy.bindings[index];
  if (binding) {
    policy.bindings.splice(index, 1);

    // Updates the bucket's IAM policy
    await bucket.iam.setPolicy(policy);

    console.log('Conditional Binding was removed.');
  } else {
    // No matching role-member group with specific condition were found
    throw new Error('No matching binding group found.');
  }
}

removeBucketConditionalBinding().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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use Google\Cloud\Storage\StorageClient;

/**
 * Removes a conditional IAM binding from a bucket's IAM policy.
 *
 * To see how to express a condition in CEL, visit:
 * @see https://cloud.google.com/storage/docs/access-control/iam#conditions.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 * @param string $role the role that will be given to members in this binding.
 * @param string $title The title of the condition.
 * @param string $description The description of the condition.
 * @param string $expression Te condition specified in CEL expression language.
 */
function remove_bucket_conditional_iam_binding($bucketName, $role, $title, $description, $expression)
{
    // $bucketName = 'my-bucket';
    // $role = 'roles/storage.objectViewer';
    // $title = 'Title';
    // $description = 'Condition Description';
    // $expression = 'resource.name.startsWith("projects/_/buckets/bucket-name/objects/prefix-a-")';

    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);

    $policy = $bucket->iam()->policy(['requestedPolicyVersion' => 3]);

    $policy['version'] = 3;

    $key_of_conditional_binding = null;
    foreach ($policy['bindings'] as $key => $binding) {
        if ($binding['role'] == $role && isset($binding['condition'])) {
            $condition = $binding['condition'];
            if ($condition['title'] == $title
                 && $condition['description'] == $description
                 && $condition['expression'] == $expression) {
                $key_of_conditional_binding = $key;
                break;
            }
        }
    }

    if ($key_of_conditional_binding != null) {
        unset($policy['bindings'][$key_of_conditional_binding]);
        // Ensure array keys are sequential, otherwise JSON encodes
        // the array as an object, which fails when calling the API.
        $policy['bindings'] = array_values($policy['bindings']);
        $bucket->iam()->setPolicy($policy);
        print('Conditional Binding was removed.' . PHP_EOL);
    } else {
        print('No matching conditional binding found.' . PHP_EOL);
    }
}

Python

For more information, see the Cloud Storage Python API reference documentation.

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from google.cloud import storage


def remove_bucket_conditional_iam_binding(
    bucket_name, role, title, description, expression
):
    """Remove a conditional IAM binding from a bucket's IAM policy."""
    # bucket_name = "your-bucket-name"
    # role = "IAM role, e.g. roles/storage.objectViewer"
    # title = "Condition title."
    # description = "Condition description."
    # expression = "Condition expression."

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)

    policy = bucket.get_iam_policy(requested_policy_version=3)

    # Set the policy's version to 3 to use condition in bindings.
    policy.version = 3

    condition = {
        "title": title,
        "description": description,
        "expression": expression,
    }
    policy.bindings = [
        binding
        for binding in policy.bindings
        if not (binding["role"] == role and binding.get("condition") == condition)
    ]

    bucket.set_iam_policy(policy)

    print("Conditional Binding was removed.")

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

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def remove_bucket_conditional_iam_binding bucket_name:
  # The ID of your GCS bucket
  # bucket_name = "your-unique-bucket-name"

  require "google/cloud/storage"

  storage = Google::Cloud::Storage.new
  bucket = storage.bucket bucket_name

  role        = "roles/storage.objectViewer"
  title       = "Title"
  description = "Description"
  expression  = "resource.name.startsWith(\"projects/_/buckets/bucket-name/objects/prefix-a-\")"

  bucket.policy requested_policy_version: 3 do |policy|
    policy.version = 3

    binding_to_remove = nil
    policy.bindings.each do |b|
      condition = {
        title:       title,
        description: description,
        expression:  expression
      }
      if (b.role == role) && (b.condition &&
        b.condition.title == title &&
        b.condition.description == description &&
        b.condition.expression == expression)
        binding_to_remove = b
      end
    end
    if binding_to_remove
      policy.bindings.remove binding_to_remove
      puts "Conditional Binding was removed."
    else
      puts "No matching conditional binding found."
    end
  end
end

JSON

1. Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.

2. Use a GET getIamPolicy request to save the bucket's IAM policy to a temporary JSON file:

   curl \
   'https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/iam' \
   --header 'Authorization: Bearer OAUTH2_TOKEN' > /tmp/policy.json

   Where:

   • BUCKET_NAME is the name of the bucket you are granting access to. For example, my-bucket.
   • OAUTH2_TOKEN is the access token you generated in Step 1.

3. Edit the /tmp/policy.json file in a text editor to remove conditions from the IAM policy.

4. Use a PUT setIamPolicy request to set the modified IAM policy on the bucket:

   curl -X PUT --data-binary @/tmp/policy.json \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     -H "Content-Type: application/json" \
     "https://storage.googleapis.com/storage/v1/b/BUCKET_NAME/iam"

   Where:

   • OAUTH2_TOKEN is the access token you generated in Step 1.
   • BUCKET_NAME is the name of the bucket whose IAM policy you want to modify. For example, my-bucket.

Using IAM with projects

The following sections show how to complete basic IAM tasks on projects. Note that these tasks use a separate command line command, gcloud, and a separate endpoint, cloudresourcemanager.googleapis.com, compared to most Cloud Storage tasks.

To complete the following tasks, you must have the resourcemanager.projects.getIamPolicy and resourcemanager.projects.setIamPolicy IAM permissions.

Adding a principal to a project-level policy

For a list of roles associated with Cloud Storage, see IAM Roles. For information on entities to which you grant IAM roles, see Principal Types.

Console

1. Open the IAM & Admin browser in the Google Cloud Console.
   Open the IAM & Admin browser

2. In the project drop-down menu on the top bar, select the project to which you want to add a principal.

3. Click Add. The Add principals, roles to project dialog appears.

4. In the New principals field, specify the name of the entity to which you are granting access.

5. In the Select a role drop down, grant the appropriate role to the principal.

   Roles that affect Cloud Storage buckets and objects are found in the Project and Storage submenus.

6. Click Save.

gsutil

Project-level IAM policies are managed through the gcloud command, which is part of the Google Cloud SDK. To add a project-level policy, use gcloud beta projects add-iam-policy-binding.

JSON

Note: This task uses a separate endpoint compared to most Cloud Storage tasks.

1. Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.

2. Create a .json file that contains the following information:

   {
     "policy": {
       "version": "0",
       "bindings": {
         "role": "IAM_ROLE",
         "members": "PRINCIPAL_NAME"
       },
     }
   }

   Where:

   • IAM_ROLE is the IAM role you are granting. For example, roles/storage.objectViewer.
   • PRINCIPAL_NAME is the type and name of the principal to which you are granting project access. For example, user:[e-mail].

3. Use cURL to call the Resource Manager API with a POST setIamPolicy request:

   curl -X POST --data-binary @JSON_FILE_NAME.json \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     -H "Content-Type: application/json" \
     "https://cloudresourcemanager.googleapis.com/v1/projects/PROJECT_ID:setIamPolicy"

   Where:

   • JSON_FILE_NAME is the name of the file you created in Step 2.
   • OAUTH2_TOKEN is the access token you generated in Step 1.
   • PROJECT_ID is the ID of the project to which you are granting access. For example, my-project.

Note: You should set the minimum permission possible that gives the principal the required access. For example, if a team member only needs to read objects stored in a project, grant the Storage Object Viewer role. Similarly, if the team member needs full control of objects (but not buckets) in a project, grant Storage Object Admin.

Viewing the IAM policy for a project

Console

1. Open the IAM & Admin browser in the Google Cloud Console.
   Open the IAM & Admin browser

2. In the project drop-down menu on the top bar, select the project whose policy you want to view.

3. There are two ways to view permissions for the project:

   • View by Principals: View the Role column associated with individual principals to see which roles each principal has.
   • View by Roles: Use the drop-down associated with individual roles to see which principals have the role.

gsutil

Project-level IAM policies are managed through the gcloud command, which is part of the Google Cloud SDK. To view the IAM policy of a project, use gcloud beta projects get-iam-policy command.

JSON

Note: This task uses a separate endpoint compared to most Cloud Storage tasks.

1. Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.

2. Use cURL to call the Resource Manager API with a POST getIamPolicy request:

   curl -X POST \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     -H "Content-Length: 0" \
     "https://cloudresourcemanager.googleapis.com/v1/projects/PROJECT_ID:getIamPolicy"

   Where:

   • OAUTH2_TOKEN is the access token you generated in Step 1.
   • PROJECT_ID is the ID of the project to which you are granting access. For example, my-project.

Removing a principal from a project-level policy

Console

1. Open the IAM & Admin browser in the Google Cloud Console.
   Open the IAM & Admin browser

2. In the project drop-down menu on the top bar, select the project from which you want to remove a principal.

3. Make sure you are viewing permissions by Principals, and select the principals you want to remove.

4. Click Remove.

5. In the overlay window that appears, click Confirm.

gsutil

Project-level IAM policies are managed through the gcloud command, which is part of the Google Cloud SDK. To remove a project-level policy, use gcloud beta projects remove-iam-policy-binding.

JSON

Note: This task uses a separate endpoint compared to most Cloud Storage tasks.

1. Get an authorization access token from the OAuth 2.0 Playground. Configure the playground to use your own OAuth credentials.

2. Get the existing policy applied to your project. To do so, use cURL to call the Resource Manager API with a POST getIamPolicy request:

   curl -X POST \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     -H "Content-Length: 0" \
     "https://cloudresourcemanager.googleapis.com/v1/projects/PROJECT_ID:getIamPolicy"

   Where:

   • OAUTH2_TOKEN is the access token you generated in Step 1.
   • PROJECT_ID is the ID of the project from which you want to remove access. For example, my-project.

3. Create a .json file that contains the policy you retrieved in the previous step.

4. Edit the .json file to remove the principal from the policy.

5. Use cURL to call the Resource Manager API with a POST setIamPolicy request:

   curl -X POST --data-binary @JSON_FILE_NAME.json \
     -H "Authorization: Bearer OAUTH2_TOKEN" \
     -H "Content-Type: application/json" \
     "https://cloudresourcemanager.googleapis.com/v1/projects/PROJECT_ID:setIamPolicy"

   Where:

   • JSON_FILE_NAME is the name of the file you created in Step 2.
   • OAUTH2_TOKEN is the access token you generated in Step 1.
   • PROJECT_ID is the ID of the project from which which you want to remove access. For example, my-project.

Important: It typically takes about a minute for revoking access to take effect. In some cases it may take longer. If you remove a user's access, this change is immediately reflected in the metadata; however, the user may still have access to the object for a short period of time.

What's next

• Learn how to publicly share your data.
• Learn more about IAM in Cloud Storage.
• See specific Sharing and collaboration examples.
• Learn about options to control access to your data.