Access control with IAM

This document describes the access control options available to you in Pub/Sub.

Overview

Pub/Sub uses Identity and Access Management (IAM) for access control.

IAM allows you to grant specific roles to users, groups, and service accounts, giving them the necessary permissions to perform their tasks. You can grant these IAM roles using the Google Cloud console or the IAM API.

In Pub/Sub, access control can be configured at the project level and at the individual resource level. Here are some examples for using Pub/Sub access control:

• Grant access on a per-resource basis, rather than for the whole Cloud project.

• Grant access with limited capabilities, such as to only publish messages to a topic, or to only consume messages from a subscription, but not to delete the topic or subscription.

• Grant access to all Pub/Sub resources within a project to a group of developers.

If you have view-only access to a single resource such as a topic or a subscription, you cannot view the resource using the Google Cloud console. Instead, you can use Google Cloud CLI to view the resource.

For a detailed description of IAM and its features, see the IAM documentation. In particular, see Granting, changing, and revoking access to resources.

Note: Pub/Sub is not associated with any specific IP address. This is relevant if you rely on IP-based firewall rules.

Types of roles in Pub/Sub

Similar to other Google Cloud products, Pub/Sub supports three types of roles:

• Basic roles: Basic roles are highly permissive roles that existed prior to the introduction of IAM. For more information about basic roles, see Basic roles.

• Predefined roles: Predefined roles give granular access to specific Google Cloud resources. For more information about predefined roles, see Predefined roles. The Pub/Sub predefined roles are included in a later part of this section.

• Custom roles: Custom roles help you enforce the principle of least privilege. For more information about custom roles, see Custom roles.

Required Pub/Sub permissions

The following sections lists Pub/Sub permissions required for accessing different Pub/Sub resources.

Required permissions for topics

The following table outlines the required permissions for each Pub/Sub API method related to topics. It shows which IAM permission is needed to call each method, along with a description of what the method does.

Method	Description	Required permission
projects.topics.create	Creates the given topic with the given name.	pubsub.topics.create on the containing Cloud project
projects.topics.delete	Deletes the topic with the given name.	pubsub.topics.delete on the requested topic
projects.topics.get	Gets the configuration of a topic.	pubsub.topics.get on the requested topic
projects.topics.getIamPolicy	Gets the IAM access control policy for a topic.	pubsub.topics.getIamPolicy on the requested topic
projects.topics.list	Lists all topics.	pubsub.topics.list on the requested Cloud project
projects.topics.patch	Updates an existing topic.	pubsub.topics.update on the requested topic
projects.topics.publish	Adds one or more messages to the topic.	pubsub.topics.publish on the requested topic
projects.topics.setIamPolicy	Sets the IAM access control policy for a topic.	pubsub.topics.setIamPolicy on the requested topic
projects.topics.testIamPermissions	Returns permissions that a caller has on the specified resource.	None

Required permissions for subscriptions

The following table outlines the required permissions for each Pub/Sub API method related to subscriptions. It shows which IAM permission is needed to call each method, along with a description of what the method does.

Method	Description	Required permission
projects.subscriptions.acknowledge	Acknowledges the messages associated with the ack_ids in the AcknowledgeRequest.	pubsub.subscriptions.consume on the requested subscription
projects.subscriptions.create	Creates a subscription to a given topic.	pubsub.subscriptions.create on the containing Cloud project and pubsub.topics.attachSubscription on the requested topic. For creating a Subscription S in Project A that is attached to a Topic T in Project B, the appropriate permissions must be granted on both Project A and on Topic T. In this case, user identity info can be captured in Project B's audit logs.
projects.subscriptions.delete	Deletes an existing subscription.	pubsub.subscriptions.delete on the requested subscription
projects.subscriptions.detach	Detaches a subscription from this topic.	pubsub.subscriptions.detach on the subscription
projects.subscriptions.get	Gets the configuration details of a subscription.	pubsub.subscriptions.get on the requested subscription
projects.subscriptions.getIamPolicy	Gets the IAM access control policy for a subscription.	pubsub.subscriptions.getIamPolicy on the requested subscription
projects.subscriptions.list	Lists matching subscriptions.	pubsub.subscriptions.list on the requested Cloud project
projects.subscriptions.modifyAckDeadline	Modifies the ack deadline for a specific message.	pubsub.subscriptions.consume on the requested subscription
projects.subscriptions.modifyPushConfig	Modifies the pushConfig for a specified subscription.	pubsub.subscriptions.update on the requested subscription
projects.subscriptions.patch	Updates an existing subscription.	pubsub.subscriptions.update on the requested subscription
projects.subscriptions.pull	Pulls messages from the server.	pubsub.subscriptions.consume on the requested subscription
projects.subscriptions.seek	Seeks an existing subscription to a point in time or a snapshot.	pubsub.subscriptions.consume on the requested subscription and pubsub.snapshots.seek on the requested snapshot, if any.
projects.subscriptions.setIamPolicy	Sets the IAM access control policy for a subscription.	pubsub.subscriptions.setIamPolicy on the requested subscription
projects.subscriptions.testIamPermissions	Returns permissions that a caller has on the specified resource.	None

Required permissions for schemas

The following table outlines the required permissions for each Pub/Sub API method related to schemas. It shows which IAM permission is needed to call each method, along with a description of what the method does.

Method	Description	Required permission
projects.schemas.commit	Commits a new schema revision.	pubsub.schemas.commit on the requested schema
projects.schemas.create	Creates a schema.	pubsub.schemas.create on the containing Cloud project
projects.schemas.delete	Deletes a schema.	pubsub.schemas.delete on the requested schema
projects.schemas.deleteRevision	Deletes a specific schema revision.	pubsub.schemas.delete on the requested schema
projects.schemas.get	Gets a schema.	pubsub.schemas.get on the requested schema
projects.schemas.getIamPolicy	Gets the IAM access control policy for a schema.	pubsub.schemas.getIamPolicy on the requested schema
projects.schemas.list	Lists schemas in a project.	pubsub.schemas.list on the requested Cloud project
projects.schemas.listRevisions	Lists all schema revisions for the named schema.	pubsub.schemas.listRevisions on the requested schema
projects.schemas.rollback	Creates a new schema revision from a previous revision.	pubsub.schemas.rollback on the requested schema
projects.schemas.validate	Validates a schema definition.	pubsub.schemas.validate on the containing Cloud project
projects.schemas.validateMessage	Validates a message against a schema.	pubsub.schemas.validate on the containing Cloud project

Required permissions for snapshots

The following table outlines the required permissions for each Pub/Sub API method related to snapshots. It shows which IAM permission is needed to call each method, along with a description of what the method does.

REST method	Description	Required permission
projects.snapshots.create	Creates a snapshot from the requested subscription.	pubsub.snapshots.create on the containing Cloud project and pubsub.subscriptions.consume permission on the source subscription.
projects.snapshots.delete	Removes an existing snapshot.	pubsub.snapshots.delete on the requested snapshot
projects.snapshots.getIamPolicy	Gets the IAM access control policy for a snapshot.	pubsub.snapshots.getIamPolicy on the requested snapshot
projects.snapshots.list	Lists the existing snapshots.	pubsub.snapshots.list on the requested Cloud project
projects.snapshots.patch	Updates an existing snapshot.	pubsub.snapshots.update on the requested snapshot
projects.snapshots.setIamPolicy	Sets the IAM access control policy for a snapshot.	pubsub.snapshots.setIamPolicy on the requested snapshot
projects.snapshots.testIamPermissions	Returns permissions that a caller has on the specified resource.	None

Available Pub/Sub roles

The following table lists all Pub/Sub roles and the permissions associated with each role:

Role	Permissions
Pub/Sub Admin (roles/pubsub.admin) Provides full access to topics and subscriptions. Lowest-level resources where you can grant this role: Schema Snapshot Subscription Topic	pubsub.* pubsub.schemas.attach pubsub.schemas.commit pubsub.schemas.create pubsub.schemas.delete pubsub.schemas.get pubsub.schemas.getIamPolicy pubsub.schemas.list pubsub.schemas.listRevisions pubsub.schemas.rollback pubsub.schemas.setIamPolicy pubsub.schemas.validate pubsub.snapshots.create pubsub.snapshots.delete pubsub.snapshots.get pubsub.snapshots.getIamPolicy pubsub.snapshots.list pubsub.snapshots.seek pubsub.snapshots.setIamPolicy pubsub.snapshots.update pubsub.subscriptions.consume pubsub.subscriptions.create pubsub.subscriptions.delete pubsub.subscriptions.get pubsub.subscriptions.getIamPolicy pubsub.subscriptions.list pubsub.subscriptions.setIamPolicy pubsub.subscriptions.update pubsub.topics.attachSubscription pubsub.topics.create pubsub.topics.delete pubsub.topics.detachSubscription pubsub.topics.get pubsub.topics.getIamPolicy pubsub.topics.list pubsub.topics.publish pubsub.topics.setIamPolicy pubsub.topics.update pubsub.topics.updateTag resourcemanager.projects.get serviceusage.quotas.get serviceusage.services.get serviceusage.services.list
Pub/Sub Editor (roles/pubsub.editor) Provides access to modify topics and subscriptions, and access to publish and consume messages. Lowest-level resources where you can grant this role: Schema Snapshot Subscription Topic	pubsub.schemas.attach pubsub.schemas.commit pubsub.schemas.create pubsub.schemas.delete pubsub.schemas.get pubsub.schemas.list pubsub.schemas.listRevisions pubsub.schemas.rollback pubsub.schemas.validate pubsub.snapshots.create pubsub.snapshots.delete pubsub.snapshots.get pubsub.snapshots.list pubsub.snapshots.seek pubsub.snapshots.update pubsub.subscriptions.consume pubsub.subscriptions.create pubsub.subscriptions.delete pubsub.subscriptions.get pubsub.subscriptions.list pubsub.subscriptions.update pubsub.topics.attachSubscription pubsub.topics.create pubsub.topics.delete pubsub.topics.detachSubscription pubsub.topics.get pubsub.topics.list pubsub.topics.publish pubsub.topics.update pubsub.topics.updateTag resourcemanager.projects.get serviceusage.quotas.get serviceusage.services.get serviceusage.services.list
Pub/Sub Publisher (roles/pubsub.publisher) Provides access to publish messages to a topic. Lowest-level resources where you can grant this role: Topic	pubsub.topics.publish
Pub/Sub Subscriber (roles/pubsub.subscriber) Provides access to consume messages from a subscription and to attach subscriptions to a topic. Lowest-level resources where you can grant this role: Snapshot Subscription Topic	pubsub.snapshots.seek pubsub.subscriptions.consume pubsub.topics.attachSubscription
Pub/Sub Viewer (roles/pubsub.viewer) Provides access to view topics and subscriptions. Lowest-level resources where you can grant this role: Schema Snapshot Subscription Topic	pubsub.schemas.get pubsub.schemas.list pubsub.schemas.listRevisions pubsub.schemas.validate pubsub.snapshots.get pubsub.snapshots.list pubsub.subscriptions.get pubsub.subscriptions.list pubsub.topics.get pubsub.topics.list resourcemanager.projects.get serviceusage.quotas.get serviceusage.services.get serviceusage.services.list

Controlling access through the Google Cloud console

You can use the Google Cloud console to manage access control for your topics and projects.

To set access controls at the project level, follow these steps:

1. In the Google Cloud console, go to the IAM page.

   Go to IAM

2. Select your project.

3. Click Add.

4. Type in one or more principal names.

5. In the Select a role list, select the role you want to grant.

6. Click Save.

7. Verify that the principal is listed with the role that you granted.

To set access controls for topics and subscriptions, follow these steps:

1. In the Google Cloud console, go to the Pub/Sub Topics list.

   Go to Topics

2. If needed, select your Pub/Sub-enabled project.

3. Perform one of the following steps:

   • To set roles for one or more topics, select the topics.

   • To set roles for a subscription attached to a topic, click the topic ID. In the Topic details page, click the subscription ID. The Subscription details page appears.

4. If the info panel is hidden, click Show info panel.

5. In the Permissions tab, click Add principal.

6. Type in one or more principal names.

7. In the Select a role list, select the role you want to grant.

8. Click Save.

Controlling access through the IAM API

The Pub/Sub IAM API lets you set and get policies on individual topics and subscriptions in a project, and test a user's permissions for a given resource. As with the regular Pub/Sub methods, you can invoke the IAM API methods through the client libraries, or the API Explorer, or directly over HTTP.

Note that you cannot use the Pub/Sub IAM API to manage policies at the Google Cloud project level.

The following sections give examples for how to set and get a policy, and how to test what permissions a caller has for a given resource.

Get a policy

The getIamPolicy() method allows you to get an existing policy. This method returns a JSON object containing the policy associated with the resource.

Here is some sample code to get a policy for a subscription:

C#

Before trying this sample, follow the C# setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub C# API reference documentation.

using Google.Cloud.Iam.V1;
using Google.Cloud.PubSub.V1;

public class GetSubscriptionIamPolicySample
{
    public Policy GetSubscriptionIamPolicy(string projectId, string subscriptionId)
    {
        PublisherServiceApiClient publisher = PublisherServiceApiClient.Create();
        SubscriptionName subscriptionName = SubscriptionName.FromProjectSubscription(projectId, subscriptionId);
        Policy policy = publisher.IAMPolicyClientte-xref-link" href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html" track-type="exampleCode" track-name="xrefLink" track-metadata-lang="DOTNET" track-metadata-modifier="Google.Cloud.Iam.V1" track-metadata-href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html">IAMPolicyClient.GetIamPolicy(new GetIamPolicyRequest
        {
            ResourceAsResourceName = subscriptionName
        });
        return policy;
    }
}

gcloud

Get the subscription policy:

gcloud pubsub subscriptions get-iam-policy \
   projects/${PROJECT}/subscriptions/${SUBSCRIPTION} \
   --format json

Output:

   {
     "etag": "BwUjMhCsNvY=",
     "bindings": [
       {
         "role": "roles/pubsub.admin",
         "members": [
           "user:[e-mail]"
         ]
       },
       {
         "role": "roles/pubsub.editor",
         "members": [
           "serviceAccount:[e-mail]",
           "user:[e-mail]"
       }
     ]
   }

Go

Before trying this sample, follow the Go setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Go API reference documentation.

import (
	"context"
	"fmt"
	"io"

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

func policy(w io.Writer, projectID, subID string) (*iam.Policy, error) {
	// projectID := "my-project-id"
	// subID := "my-sub"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return nil, fmt.Errorf("pubsub.NewClient: %w", err)
	}
	defer client.Close()

	policy, err := client.Subscription(subID).IAM().Policy(ctx)
	if err != nil {
		return nil, fmt.Errorf("Subscription: %w", err)
	}
	for _, role := range policy.Roles() {
		fmt.Fprintf(w, "%q: %q\n", role, policy.Members(role))
	}
	return policy, nil
}

Java

Before trying this sample, follow the Java setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Java API reference documentation.

import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
import com.google.iam.v1.GetIamPolicyRequest;
import com.google.iam.v1.Policy;
import com.google.pubsub.v1.ProjectSubscriptionName;
import java.io.IOException;

public class GetSubscriptionPolicyExample {
  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String subscriptionId = "your-subscription-id";

    getSubscriptionPolicyExample(projectId, subscriptionId);
  }

  public static void getSubscriptionPolicyExample(String projectId, String subscriptionId)
      throws IOException {
    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
      ProjectSubscriptionName subscriptionName =
          ProjectSubscriptionName.of(projectId, subscriptionId);
      GetIamPolicyRequest getIamPolicyRequest =
          GetIamPolicyRequest.newBuilder().setResource(subscriptionName.toString()).build();
      Policy policy = subscriptionAdminClient.getIamPolicy(getIamPolicyRequest);
      System.out.println("Subscription policy: " + policy);
    }
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Node.js API reference documentation.

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const subscriptionNameOrId = 'YOUR_SUBSCRIPTION_NAME_OR_ID';

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

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function getSubscriptionPolicy(subscriptionNameOrId) {
  // Retrieves the IAM policy for the subscription
  const [policy] = await pubSubClient
    .subscription(subscriptionNameOrId)
    .iam.getPolicy();

  console.log(`Policy for subscription: ${JSON.stringify(policy.bindings)}.`);
}

Node.js

Before trying this sample, follow the Node.js setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Node.js API reference documentation.

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const subscriptionNameOrId = 'YOUR_SUBSCRIPTION_NAME_OR_ID';

// Imports the Google Cloud client library
import {PubSub, Policy} from '@google-cloud/pubsub';

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function getSubscriptionPolicy(subscriptionNameOrId: string) {
  // Retrieves the IAM policy for the subscription
  const [policy]: [Policy] = await pubSubClient
    .subscription(subscriptionNameOrId)
    .iam.getPolicy();

  console.log(`Policy for subscription: ${JSON.stringify(policy.bindings)}.`);
}

PHP

Before trying this sample, follow the PHP setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub PHP API reference documentation.

use Google\Cloud\PubSub\PubSubClient;

/**
 * Prints the policy for a PubSub subscription.
 *
 * @param string $projectId  The Google project ID.
 * @param string $subscriptionName  The Pub/Sub subscription name.
 */
function get_subscription_policy($projectId, $subscriptionName)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);
    $subscription = $pubsub->subscription($subscriptionName);
    $policy = $subscription->iam()->policy();
    print_r($policy);
}

Python

Before trying this sample, follow the Python setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Python API reference documentation.

from google.cloud import pubsub_v1

# TODO(developer): Choose an existing subscription.
# project_id = "your-project-id"
# subscription_id = "your-subscription-id"

client = pubsub_v1.SubscriberClient()
subscription_path = client.subscription_path(project_id, subscription_id)

policy = client.get_iam_policy(request={"resource": subscription_path})

print("Policy for subscription {}:".format(subscription_path))
for binding in policy.bindings:
    print("Role: {}, Members: {}".format(binding.role, binding.members))

client.close()

Ruby

Before trying this sample, follow the Ruby setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Ruby API reference documentation.

# subscription_id = "your-subscription-id"

pubsub = Google::Cloud::Pubsub.new

subscription = pubsub.subscription subscription_id
policy       = subscription.policy

puts "Subscription policy:"
puts policy.roles

Here is some sample code to get a policy for a topic:

C#

Before trying this sample, follow the C# setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub C# API reference documentation.

using Google.Cloud.Iam.V1;
using Google.Cloud.PubSub.V1;

public class GetTopicIamPolicySample
{
    public Policy GetTopicIamPolicy(string projectId, string topicId)
    {
        PublisherServiceApiClient publisher = PublisherServiceApiClient.Create();
        TopicName topicName = TopicName.FromProjectTopic(projectId, topicId);
        Policy policy = publisher.IAMPolicyClientte-xref-link" href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html" track-type="exampleCode" track-name="xrefLink" track-metadata-lang="DOTNET" track-metadata-modifier="Google.Cloud.Iam.V1" track-metadata-href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html">IAMPolicyClient.GetIamPolicy(new GetIamPolicyRequest
        {
            ResourceAsResourceName = topicName
        });
        return policy;
    }
}

gcloud

Get the topic policy

gcloud pubsub topics get-iam-policy \
    projects/${PROJECT}/topics/${TOPIC} \
    --format json

Output:

{
  "etag": "BwUjMhCsNvY=",
  "bindings": [
    {
      "role":" roles/pubsub.viewer",
      "members": [
        "user:[e-mail]"
      ]
    }
  ]
}

Go

Before trying this sample, follow the Go setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Go API reference documentation.

import (
	"context"
	"fmt"
	"io"

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

func policy(w io.Writer, projectID, topicID string) (*iam.Policy, error) {
	// projectID := "my-project-id"
	// topicID := "my-topic"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return nil, fmt.Errorf("pubsub.NewClient: %w", err)
	}
	defer client.Close()

	policy, err := client.Topic(topicID).IAM().Policy(ctx)
	if err != nil {
		return nil, fmt.Errorf("Policy: %w", err)
	}
	for _, role := range policy.Roles() {
		fmt.Fprint(w, policy.Members(role))
	}
	return policy, nil
}

Java

Before trying this sample, follow the Java setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Java API reference documentation.

import com.google.cloud.pubsub.v1.TopicAdminClient;
import com.google.iam.v1.GetIamPolicyRequest;
import com.google.iam.v1.Policy;
import com.google.pubsub.v1.TopicName;
import java.io.IOException;

public class GetTopicPolicyExample {
  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String topicId = "your-topic-id";

    getTopicPolicyExample(projectId, topicId);
  }

  public static void getTopicPolicyExample(String projectId, String topicId) throws IOException {
    try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
      TopicName topicName = TopicName.of(projectId, topicId);
      GetIamPolicyRequest getIamPolicyRequest =
          GetIamPolicyRequest.newBuilder().setResource(topicName.toString()).build();
      Policy policy = topicAdminClient.getIamPolicy(getIamPolicyRequest);
      System.out.println("Topic policy: " + policy);
    }
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Node.js API reference documentation.

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';

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

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function getTopicPolicy(topicNameOrId) {
  // Retrieves the IAM policy for the topic
  const [policy] = await pubSubClient.topic(topicNameOrId).iam.getPolicy();
  console.log('Policy for topic: %j.', policy.bindings);
}

PHP

Before trying this sample, follow the PHP setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub PHP API reference documentation.

use Google\Cloud\PubSub\PubSubClient;

/**
 * Prints the policy for a Pub/Sub topic.
 *
 * @param string $projectId  The Google project ID.
 * @param string $topicName  The Pub/Sub topic name.
 */
function get_topic_policy($projectId, $topicName)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);
    $topic = $pubsub->topic($topicName);
    $policy = $topic->iam()->policy();
    print_r($policy);
}

Python

Before trying this sample, follow the Python setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Python API reference documentation.

from google.cloud import pubsub_v1

# TODO(developer): Choose an existing topic.
# project_id = "your-project-id"
# topic_id = "your-topic-id"

client = pubsub_v1.PublisherClient()
topic_path = client.topic_path(project_id, topic_id)

policy = client.get_iam_policy(request={"resource": topic_path})

print("Policy for topic {}:".format(topic_path))
for binding in policy.bindings:
    print("Role: {}, Members: {}".format(binding.role, binding.members))

Ruby

Before trying this sample, follow the Ruby setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Ruby API reference documentation.

# topic_id = "your-topic-id"

pubsub = Google::Cloud::Pubsub.new

topic  = pubsub.topic topic_id
policy = topic.policy

puts "Topic policy:"
puts policy.roles

Set a policy

The setIamPolicy() method lets you attach a policy to a resource. The setIamPolicy() method takes a SetIamPolicyRequest, which contains the policy to be set and the resource to which the policy is attached. It returns the resulting policy.

Here is some sample code to set a policy for a subscription:

C#

Before trying this sample, follow the C# setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub C# API reference documentation.

using Google.Cloud.Iam.V1;
using Google.Cloud.PubSub.V1;

public class SetSubscriptionIamPolicySample
{
    public Policy SetSubscriptionIamPolicy(string projectId, string subscriptionId, string role, string member)
    {
        PublisherServiceApiClient publisher = PublisherServiceApiClient.Create();
        string roleToBeAddedToPolicy = $"roles/{role}";

        Policy policy = new Policy
        {
            Bindings = {
                new Binding
                {
                    Role = roleToBeAddedToPolicy,
                    Members = { member }
                }
            }
        };
        SetIamPolicyRequest request = new SetIamPolicyRequest
        {
            ResourceAsResourceName = SubscriptionName.FromProjectSubscription(projectId, subscriptionId),
            Policy = policy
        };
        Policy response = publisher.IAMPolicyClientte-xref-link" href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html" track-type="exampleCode" track-name="xrefLink" track-metadata-lang="DOTNET" track-metadata-modifier="Google.Cloud.Iam.V1" track-metadata-href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html">IAMPolicyClient.SetIamPolicy(request);
        return response;
    }
}

gcloud

1. Save the policy for the subscription.

gcloud pubsub subscriptions get-iam-policy \
   projects/${PROJECT}/subscriptions/${SUBSCRIPTION} \
   --format json > subscription_policy.json

2. Open subscription_policy.json and update bindings by giving appropriate roles to appropriate principals. For more information about working with subscription_policy.json files, see Policy in the IAM documentation.

   {
     "etag": "BwUjMhCsNvY=",
     "bindings": [
       {
         "role": "roles/pubsub.admin",
         "members": [
           "user:[e-mail]"
         ]
       },
       {
         "role": "roles/pubsub.editor",
         "members": [
           "serviceAccount:[e-mail]"
       }
     ]
   }

3. Apply the new subscription policy.

gcloud pubsub subscriptions set-iam-policy \
  projects/${PROJECT}/subscriptions/${SUBSCRIPTION} \
  subscription_policy.json

Go

Before trying this sample, follow the Go setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Go API reference documentation.

import (
	"context"
	"fmt"

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

// addUsers adds all IAM users to a subscription.
func addUsers(projectID, subID string) error {
	// projectID := "my-project-id"
	// subID := "my-sub"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub.NewClient: %w", err)
	}
	defer client.Close()

	sub := client.Subscription(subID)
	policy, err := sub.IAM().Policy(ctx)
	if err != nil {
		return fmt.Errorf("err getting IAM Policy: %w", err)
	}
	// Other valid prefixes are "serviceAccount:", "user:"
	// See the documentation for more values.
	policy.Add(iam.AllUsers, iam.Viewer)
	policy.Add("group:[e-mail]", iam.Editor)
	if err := sub.IAM().SetPolicy(ctx, policy); err != nil {
		return fmt.Errorf("SetPolicy: %w", 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.
	return nil
}

Java

Before trying this sample, follow the Java setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Java API reference documentation.

import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
import com.google.iam.v1.Binding;
import com.google.iam.v1.GetIamPolicyRequest;
import com.google.iam.v1.Policy;
import com.google.iam.v1.SetIamPolicyRequest;
import com.google.pubsub.v1.ProjectSubscriptionName;
import java.io.IOException;

public class SetSubscriptionPolicyExample {
  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String subscriptionId = "your-subscription-id";

    setSubscriptionPolicyExample(projectId, subscriptionId);
  }

  public static void setSubscriptionPolicyExample(String projectId, String subscriptionId)
      throws IOException {
    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
      ProjectSubscriptionName subscriptionName =
          ProjectSubscriptionName.of(projectId, subscriptionId);
      GetIamPolicyRequest getIamPolicyRequest =
          GetIamPolicyRequest.newBuilder().setResource(subscriptionName.toString()).build();
      Policy oldPolicy = subscriptionAdminClient.getIamPolicy(getIamPolicyRequest);

      // Create new role -> members binding
      Binding binding =
          Binding.newBuilder()
              .setRole("roles/pubsub.editor")
              .addMembers("domain:google.com")
              .build();

      // Add new binding to updated policy
      Policy updatedPolicy = Policy.newBuilder(oldPolicy).addBindings(binding).build();

      SetIamPolicyRequest setIamPolicyRequest =
          SetIamPolicyRequest.newBuilder()
              .setResource(subscriptionName.toString())
              .setPolicy(updatedPolicy)
              .build();
      Policy newPolicy = subscriptionAdminClient.setIamPolicy(setIamPolicyRequest);
      System.out.println("New subscription policy: " + newPolicy);
    }
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Node.js API reference documentation.

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const subscriptionNameOrId = 'YOUR_SUBSCRIPTION_NAME_OR_ID';

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

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function setSubscriptionPolicy(subscriptionNameOrId) {
  // The new IAM policy
  const newPolicy = {
    bindings: [
      {
        // Add a group as editors
        role: 'roles/pubsub.editor',
        members: ['group:[e-mail]'],
      },
      {
        // Add all users as viewers
        role: 'roles/pubsub.viewer',
        members: ['allUsers'],
      },
    ],
  };

  // Updates the IAM policy for the subscription
  const [updatedPolicy] = await pubSubClient
    .subscription(subscriptionNameOrId)
    .iam.setPolicy(newPolicy);

  console.log('Updated policy for subscription: %j', updatedPolicy.bindings);
}

PHP

use Google\Cloud\PubSub\PubSubClient;

/**
 * Adds a user to the policy for a Pub/Sub subscription.
 *
 * @param string $projectId  The Google project ID.
 * @param string $subscriptionName  The Pub/Sub subscription name.
 * @param string $userEmail  The user email to add to the policy.
 */
function set_subscription_policy($projectId, $subscriptionName, $userEmail)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);
    $subscription = $pubsub->subscription($subscriptionName);
    $policy = $subscription->iam()->policy();
    $policy['bindings'][] = [
        'role' => 'roles/pubsub.subscriber',
        'members' => ['user:' . $userEmail]
    ];
    $subscription->iam()->setPolicy($policy);

    printf(
        'User %s added to policy for %s' . PHP_EOL,
        $userEmail,
        $subscriptionName
    );
}

Python

Before trying this sample, follow the Python setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Python API reference documentation.

from google.cloud import pubsub_v1

# TODO(developer): Choose an existing subscription.
# project_id = "your-project-id"
# subscription_id = "your-subscription-id"

client = pubsub_v1.SubscriberClient()
subscription_path = client.subscription_path(project_id, subscription_id)

policy = client.get_iam_policy(request={"resource": subscription_path})

# Add all users as viewers.
policy.bindings.add(role="roles/pubsub.viewer", members=["domain:google.com"])

# Add a group as an editor.
policy.bindings.add(role="roles/editor", members=["group:[e-mail]"])

# Set the policy
policy = client.set_iam_policy(
    request={"resource": subscription_path, "policy": policy}
)

print("IAM policy for subscription {} set: {}".format(subscription_id, policy))

client.close()

Ruby

Before trying this sample, follow the Ruby setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Ruby API reference documentation.

# subscription_id       = "your-subscription-id"
# role                  = "roles/pubsub.publisher"
# service_account_email = "serviceAccount:account_name@project_name.iam.gserviceaccount.com"

pubsub = Google::Cloud::Pubsub.new

subscription = pubsub.subscription subscription_id
subscription.policy do |policy|
  policy.add role, service_account_email
end

Here is some sample code to set a policy for a topic:

C#

Before trying this sample, follow the C# setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub C# API reference documentation.

using Google.Cloud.Iam.V1;
using Google.Cloud.PubSub.V1;

public class SetTopicIamPolicySample
{
    public Policy SetTopicIamPolicy(string projectId, string topicId, string role, string member)
    {
        PublisherServiceApiClient publisher = PublisherServiceApiClient.Create();
        string roleToBeAddedToPolicy = $"roles/{role}";

        Policy policy = new Policy
        {
            Bindings = {
                new Binding
                {
                    Role = roleToBeAddedToPolicy,
                    Members = { member }
                }
            }
        };
        SetIamPolicyRequest request = new SetIamPolicyRequest
        {
            ResourceAsResourceName = TopicName.FromProjectTopic(projectId, topicId),
            Policy = policy
        };
        Policy response = publisher.IAMPolicyClientte-xref-link" href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html" track-type="exampleCode" track-name="xrefLink" track-metadata-lang="DOTNET" track-metadata-modifier="Google.Cloud.Iam.V1" track-metadata-href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html">IAMPolicyClient.SetIamPolicy(request);
        return response;
    }
}

gcloud

1. Save the policy for the topic.

gcloud pubsub topics get-iam-policy \
   projects/${PROJECT}/topics/${TOPIC} \
   --format json > topic_policy.json

2. Open topic_policy.json and update bindings by giving appropriate roles to appropriate principals. For more information about working with subscription_policy.json files, see Policy in the IAM documentation.

   {
     "etag": "BwUjMhCsNvY=",
     "bindings": [
       {
         "role": "roles/pubsub.editor",
         "members": [
           "user:[e-mail]",
           "user:[e-mail]"
         ]
       }
     ]
   }

3. Apply the new topic policy.

gcloud pubsub topics set-iam-policy  \
   projects/${PROJECT}/topics/${TOPIC}     \
   topic_policy.json

Go

Before trying this sample, follow the Go setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Go API reference documentation.

import (
	"context"
	"fmt"

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

func addUsers(projectID, topicID string) error {
	// projectID := "my-project-id"
	// topicID := "my-topic"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub.NewClient: %w", err)
	}
	defer client.Close()

	topic := client.Topic(topicID)
	policy, err := topic.IAM().Policy(ctx)
	if err != nil {
		return fmt.Errorf("Policy: %w", err)
	}
	// Other valid prefixes are "serviceAccount:", "user:"
	// See the documentation for more values.
	policy.Add(iam.AllUsers, iam.Viewer)
	policy.Add("group:[e-mail]", iam.Editor)
	if err := topic.IAM().SetPolicy(ctx, policy); err != nil {
		return fmt.Errorf("SetPolicy: %w", 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.
	return nil
}

Java

Before trying this sample, follow the Java setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Java API reference documentation.

import com.google.cloud.pubsub.v1.TopicAdminClient;
import com.google.iam.v1.Binding;
import com.google.iam.v1.GetIamPolicyRequest;
import com.google.iam.v1.Policy;
import com.google.iam.v1.SetIamPolicyRequest;
import com.google.pubsub.v1.TopicName;
import java.io.IOException;

public class SetTopicPolicyExample {
  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String topicId = "your-topic-id";

    setTopicPolicyExample(projectId, topicId);
  }

  public static void setTopicPolicyExample(String projectId, String topicId) throws IOException {
    try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
      TopicName topicName = TopicName.of(projectId, topicId);
      GetIamPolicyRequest getIamPolicyRequest =
          GetIamPolicyRequest.newBuilder().setResource(topicName.toString()).build();
      Policy oldPolicy = topicAdminClient.getIamPolicy(getIamPolicyRequest);

      // Create new role -> members binding
      Binding binding =
          Binding.newBuilder()
              .setRole("roles/pubsub.editor")
              .addMembers("domain:google.com")
              .build();

      // Add new binding to updated policy
      Policy updatedPolicy = Policy.newBuilder(oldPolicy).addBindings(binding).build();

      SetIamPolicyRequest setIamPolicyRequest =
          SetIamPolicyRequest.newBuilder()
              .setResource(topicName.toString())
              .setPolicy(updatedPolicy)
              .build();
      Policy newPolicy = topicAdminClient.setIamPolicy(setIamPolicyRequest);
      System.out.println("New topic policy: " + newPolicy);
    }
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Node.js API reference documentation.

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';

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

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function setTopicPolicy(topicNameOrId) {
  // The new IAM policy
  const newPolicy = {
    bindings: [
      {
        // Add a group as editors
        role: 'roles/pubsub.editor',
        members: ['group:[e-mail]'],
      },
      {
        // Add all users as viewers
        role: 'roles/pubsub.viewer',
        members: ['allUsers'],
      },
    ],
  };

  // Updates the IAM policy for the topic
  const [updatedPolicy] = await pubSubClient
    .topic(topicNameOrId)
    .iam.setPolicy(newPolicy);
  console.log('Updated policy for topic: %j', updatedPolicy.bindings);
}

PHP

use Google\Cloud\PubSub\PubSubClient;

/**
 * Adds a user to the policy for a Pub/Sub topic.
 *
 * @param string $projectId  The Google project ID.
 * @param string $topicName  The Pub/Sub topic name.
 * @param string $userEmail  The user email to add to the policy.
 */
function set_topic_policy($projectId, $topicName, $userEmail)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);
    $topic = $pubsub->topic($topicName);
    $policy = $topic->iam()->policy();
    $policy['bindings'][] = [
        'role' => 'roles/pubsub.publisher',
        'members' => ['user:' . $userEmail]
    ];
    $topic->iam()->setPolicy($policy);

    printf(
        'User %s added to policy for %s' . PHP_EOL,
        $userEmail,
        $topicName
    );
}

Python

Before trying this sample, follow the Python setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Python API reference documentation.

from google.cloud import pubsub_v1

# TODO(developer): Choose an existing topic.
# project_id = "your-project-id"
# topic_id = "your-topic-id"

client = pubsub_v1.PublisherClient()
topic_path = client.topic_path(project_id, topic_id)

policy = client.get_iam_policy(request={"resource": topic_path})

# Add all users as viewers.
policy.bindings.add(role="roles/pubsub.viewer", members=["domain:google.com"])

# Add a group as a publisher.
policy.bindings.add(
    role="roles/pubsub.publisher", members=["group:[e-mail]"]
)

# Set the policy
policy = client.set_iam_policy(request={"resource": topic_path, "policy": policy})

print("IAM policy for topic {} set: {}".format(topic_id, policy))

Ruby

Before trying this sample, follow the Ruby setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Ruby API reference documentation.

# topic_id              = "your-topic-id"
# role                  = "roles/pubsub.publisher"
# service_account_email = "serviceAccount:account_name@project_name.iam.gserviceaccount.com"

pubsub = Google::Cloud::Pubsub.new

topic = pubsub.topic topic_id
topic.policy do |policy|
  policy.add role, service_account_email
end

Test permissions

You can use the testIamPermissions() method to check which of the given permissions can be added or removed for the given resource. It takes as parameters a resource name and a set of permissions, and returns the subset of permissions.

Note: The testIamPermissions is designed to test permission-aware UIs and command-line tools, not authorization. This operation might fail open without warning.

Here is some sample code to test permissions for a subscription:

C#

Before trying this sample, follow the C# setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub C# API reference documentation.

using Google.Cloud.Iam.V1;
using Google.Cloud.PubSub.V1;

public class TestSubscriptionIamPermissionsSample
{
    public TestIamPermissionsResponse TestSubscriptionIamPermissionsResponse(string projectId, string subscriptionId)
    {
        TestIamPermissionsRequest request = new TestIamPermissionsRequest
        {
            ResourceAsResourceName = SubscriptionName.FromProjectSubscription(projectId, subscriptionId),
            Permissions = { "pubsub.subscriptions.get", "pubsub.subscriptions.update" }
        };
        PublisherServiceApiClient publisher = PublisherServiceApiClient.Create();
        TestIamPermissionsResponse response = publisher.IAMPolicyClientte-xref-link" href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html" track-type="exampleCode" track-name="xrefLink" track-metadata-lang="DOTNET" track-metadata-modifier="Google.Cloud.Iam.V1" track-metadata-href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html">IAMPolicyClient.TestIamPermissions(request);
        return response;
    }
}

gcloud

gcloud iam list-testable-permissions \
   https://pubsub.googleapis.com/v1/projects/${PROJECT}/subscriptions/${SUBSCRIPTION} \
   --format json

Output:

 [
    {
     "name": "pubsub.subscriptions.consume",
     "stage": "GA"
   },
   {
     "name": "pubsub.subscriptions.delete",
     "stage": "GA"
   },
   {
     "name": "pubsub.subscriptions.get",
     "stage": "GA"
   },
   {
     "name": "pubsub.subscriptions.getIamPolicy",
     "stage": "GA"
    },
   {
     "name": "pubsub.subscriptions.setIamPolicy",
     "stage": "GA"
   },
   {
     "name": "pubsub.subscriptions.update",
     "stage": "GA"
   }
 ]

Go

Before trying this sample, follow the Go setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Go API reference documentation.

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/pubsub"
)

func testPermissions(w io.Writer, projectID, subID string) ([]string, error) {
	// projectID := "my-project-id"
	// subID := "my-sub"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return nil, fmt.Errorf("pubsub.NewClient: %w", err)
	}

	sub := client.Subscription(subID)
	perms, err := sub.IAM().TestPermissions(ctx, []string{
		"pubsub.subscriptions.consume",
		"pubsub.subscriptions.update",
	})
	if err != nil {
		return nil, fmt.Errorf("TestPermissions: %w", err)
	}
	for _, perm := range perms {
		fmt.Fprintf(w, "Allowed: %v\n", perm)
	}

Java

Before trying this sample, follow the Java setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Java API reference documentation.

import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
import com.google.iam.v1.TestIamPermissionsRequest;
import com.google.iam.v1.TestIamPermissionsResponse;
import com.google.pubsub.v1.ProjectSubscriptionName;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;

public class TestSubscriptionPermissionsExample {
  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String subscriptionId = "your-subscription-id";

    testSubscriptionPermissionsExample(projectId, subscriptionId);
  }

  public static void testSubscriptionPermissionsExample(String projectId, String subscriptionId)
      throws IOException {
    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
      ProjectSubscriptionName subscriptionName =
          ProjectSubscriptionName.of(projectId, subscriptionId);

      List<String> permissions = new LinkedList<>();
      permissions.add("pubsub.subscriptions.consume");
      permissions.add("pubsub.subscriptions.update");

      TestIamPermissionsRequest testIamPermissionsRequest =
          TestIamPermissionsRequest.newBuilder()
              .setResource(subscriptionName.toString())
              .addAllPermissions(permissions)
              .build();

      TestIamPermissionsResponse testedPermissionsResponse =
          subscriptionAdminClient.testIamPermissions(testIamPermissionsRequest);

      System.out.println("Tested:\n" + testedPermissionsResponse);
    }
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Node.js API reference documentation.

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const subscriptionNameOrId = 'YOUR_SUBSCRIPTION_NAME_OR_ID';

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

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function testSubscriptionPermissions(subscriptionNameOrId) {
  const permissionsToTest = [
    'pubsub.subscriptions.consume',
    'pubsub.subscriptions.update',
  ];

  // Tests the IAM policy for the specified subscription
  const [permissions] = await pubSubClient
    .subscription(subscriptionNameOrId)
    .iam.testPermissions(permissionsToTest);

  console.log('Tested permissions for subscription: %j', permissions);
}

PHP

Before trying this sample, follow the PHP setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub PHP API reference documentation.

use Google\Cloud\PubSub\PubSubClient;

/**
 * Prints the permissions of a subscription.
 *
 * @param string $projectId  The Google project ID.
 * @param string $subscriptionName  The Pub/Sub subscription name.
 */
function test_subscription_permissions($projectId, $subscriptionName)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);
    $subscription = $pubsub->subscription($subscriptionName);
    $permissions = $subscription->iam()->testPermissions([
        'pubsub.subscriptions.consume',
        'pubsub.subscriptions.update'
    ]);
    foreach ($permissions as $permission) {
        printf('Permission: %s' . PHP_EOL, $permission);
    }
}

Python

Before trying this sample, follow the Python setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Python API reference documentation.

from google.cloud import pubsub_v1

# TODO(developer): Choose an existing subscription.
# project_id = "your-project-id"
# subscription_id = "your-subscription-id"

client = pubsub_v1.SubscriberClient()
subscription_path = client.subscription_path(project_id, subscription_id)

permissions_to_check = [
    "pubsub.subscriptions.consume",
    "pubsub.subscriptions.update",
]

allowed_permissions = client.test_iam_permissions(
    request={"resource": subscription_path, "permissions": permissions_to_check}
)

print(
    "Allowed permissions for subscription {}: {}".format(
        subscription_path, allowed_permissions
    )
)

client.close()

Ruby

Before trying this sample, follow the Ruby setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Ruby API reference documentation.

# subscription_id = "your-subscription-id"

pubsub = Google::Cloud::Pubsub.new

subscription = pubsub.subscription subscription_id
permissions  = subscription.test_permissions "pubsub.subscriptions.consume",
                                             "pubsub.subscriptions.update"

puts "Permission to consume" if permissions.include? "pubsub.subscriptions.consume"
puts "Permission to update" if permissions.include? "pubsub.subscriptions.update"

Here is some sample code to test permissions for a topic:

C#

Before trying this sample, follow the C# setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub C# API reference documentation.

using Google.Cloud.Iam.V1;
using Google.Cloud.PubSub.V1;

public class TestTopicIamPermissionsSample
{
    public TestIamPermissionsResponse TestTopicIamPermissions(string projectId, string topicId)
    {
        TestIamPermissionsRequest request = new TestIamPermissionsRequest
        {
            ResourceAsResourceName = TopicName.FromProjectTopic(projectId, topicId),
            Permissions = { "pubsub.topics.get", "pubsub.topics.update" }
        };
        PublisherServiceApiClient publisher = PublisherServiceApiClient.Create();
        TestIamPermissionsResponse response = publisher.IAMPolicyClientte-xref-link" href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html" track-type="exampleCode" track-name="xrefLink" track-metadata-lang="DOTNET" track-metadata-modifier="Google.Cloud.Iam.V1" track-metadata-href="https://cloud.google.com/dotnet/docs/reference/Google.Cloud.Iam.V1/latest/Google.Cloud.Iam.V1.IAMPolicyClient.html">IAMPolicyClient.TestIamPermissions(request);
        return response;
    }
}

gcloud

gcloud iam list-testable-permissions \
   https://pubsub.googleapis.com/v1/projects/${PROJECT}/topics/${TOPIC} \
   --format json

Output

 [
   {
     "name": "pubsub.topics.attachSubscription",
     "stage": "GA"
   },
   {
     "name": "pubsub.topics.delete",
     "stage": "GA"
   },
   {
     "name": "pubsub.topics.detachSubscription",
     "stage": "GA"
   },
   {
     "name": "pubsub.topics.get",
     "stage": "GA"
   },
   {
     "name": "pubsub.topics.getIamPolicy",
     "stage": "GA"
   },
   {
     "name": "pubsub.topics.publish",
     "stage": "GA"
   },
   {
     "name": "pubsub.topics.setIamPolicy",
     "stage": "GA"
   },
   {
     "name": "pubsub.topics.update",
     "stage": "GA"
   }
 ]

Go

Before trying this sample, follow the Go setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Go API reference documentation.

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/pubsub"
)

func testPermissions(w io.Writer, projectID, topicID string) ([]string, error) {
	// projectID := "my-project-id"
	// topicID := "my-topic"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return nil, fmt.Errorf("pubsub.NewClient: %w", err)
	}

	topic := client.Topic(topicID)
	perms, err := topic.IAM().TestPermissions(ctx, []string{
		"pubsub.topics.publish",
		"pubsub.topics.update",
	})
	if err != nil {
		return nil, fmt.Errorf("TestPermissions: %w", err)
	}
	for _, perm := range perms {
		fmt.Fprintf(w, "Allowed: %v\n", perm)
	}
	return perms, nil
}

Java

Before trying this sample, follow the Java setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Java API reference documentation.

import com.google.cloud.pubsub.v1.TopicAdminClient;
import com.google.iam.v1.TestIamPermissionsRequest;
import com.google.iam.v1.TestIamPermissionsResponse;
import com.google.pubsub.v1.ProjectTopicName;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;

public class TestTopicPermissionsExample {

  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    String topicId = "your-topic-id";

    testTopicPermissionsExample(projectId, topicId);
  }

  public static void testTopicPermissionsExample(String projectId, String topicId)
      throws IOException {
    try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
      ProjectTopicName topicName = ProjectTopicName.of(projectId, topicId);

      List<String> permissions = new LinkedList<>();
      permissions.add("pubsub.topics.attachSubscription");
      permissions.add("pubsub.topics.publish");
      permissions.add("pubsub.topics.update");

      TestIamPermissionsRequest testIamPermissionsRequest =
          TestIamPermissionsRequest.newBuilder()
              .setResource(topicName.toString())
              .addAllPermissions(permissions)
              .build();

      TestIamPermissionsResponse testedPermissionsResponse =
          topicAdminClient.testIamPermissions(testIamPermissionsRequest);

      System.out.println("Tested:\n" + testedPermissionsResponse);
    }
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Node.js API reference documentation.

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';

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

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function testTopicPermissions(topicNameOrId) {
  const permissionsToTest = [
    'pubsub.topics.attachSubscription',
    'pubsub.topics.publish',
    'pubsub.topics.update',
  ];

  // Tests the IAM policy for the specified topic
  const [permissions] = await pubSubClient
    .topic(topicNameOrId)
    .iam.testPermissions(permissionsToTest);

  console.log('Tested permissions for topic: %j', permissions);
}

PHP

Before trying this sample, follow the PHP setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub PHP API reference documentation.

use Google\Cloud\PubSub\PubSubClient;

/**
 * Prints the permissions of a topic.
 *
 * @param string $projectId  The Google project ID.
 * @param string $topicName  The Pub/Sub topic name.
 */
function test_topic_permissions($projectId, $topicName)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);
    $topic = $pubsub->topic($topicName);
    $permissions = $topic->iam()->testPermissions([
        'pubsub.topics.attachSubscription',
        'pubsub.topics.publish',
        'pubsub.topics.update'
    ]);
    foreach ($permissions as $permission) {
        printf('Permission: %s' . PHP_EOL, $permission);
    }
}

Python

Before trying this sample, follow the Python setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Python API reference documentation.

from google.cloud import pubsub_v1

# TODO(developer): Choose an existing topic.
# project_id = "your-project-id"
# topic_id = "your-topic-id"

client = pubsub_v1.PublisherClient()
topic_path = client.topic_path(project_id, topic_id)

permissions_to_check = ["pubsub.topics.publish", "pubsub.topics.update"]

allowed_permissions = client.test_iam_permissions(
    request={"resource": topic_path, "permissions": permissions_to_check}
)

print(
    "Allowed permissions for topic {}: {}".format(topic_path, allowed_permissions)
)

Ruby

Before trying this sample, follow the Ruby setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Ruby API reference documentation.

# topic_id = "your-topic-id"

pubsub = Google::Cloud::Pubsub.new

topic       = pubsub.topic topic_id
permissions = topic.test_permissions "pubsub.topics.attachSubscription",
                                     "pubsub.topics.publish", "pubsub.topics.update"

puts "Permission to attach subscription" if permissions.include? "pubsub.topics.attachSubscription"
puts "Permission to publish" if permissions.include? "pubsub.topics.publish"
puts "Permission to update" if permissions.include? "pubsub.topics.update"

Cross-project communication

Pub/Sub IAM is useful for fine-tuning access in cross-project communication.

Suppose a service account in Cloud Project A wants to publish messages to a topic in Cloud Project B. First, enable the Pub/Sub API in Project A.

Second, grant the service account Edit permission in Cloud Project B. However, this approach is often too coarse. You can use the IAM API to achieve a more fine-grained level of access.

For example, this snippet uses the setIamPolicy() method in project-b and a prepared topic_policy.json file to grant the service account [e-mail] of project-a the publisher role on the topic projects/project-b/topics/topic-b:

gcloud pubsub topics set-iam-policy \
    projects/project-b/topics/topic-b \
    topic_policy.json

Output:

Updated IAM policy for topic topic-b.
bindings:
- members:
  - serviceAccount:[e-mail]
  role: roles/pubsub.publisher
etag: BwWGrQYX6R4=

Partial availability behavior

Authorization checks depend on the IAM subsystem. In order to offer consistently low response latency for data operations (publishing and message consumption), the system may fall back on cached IAM policies. For information about when your changes will take effect, see the IAM documentation.