Manage GCP Pub/Sub Subscription IAM Policies

The gcp:pubsub/subscriptionIAMPolicy:SubscriptionIAMPolicy resource, part of the Pulumi GCP provider, manages IAM policies for Pub/Sub subscriptions. This guide focuses on three approaches: authoritative policy replacement, role-level member binding, and incremental member addition.

GCP provides three related resources for subscription IAM management. SubscriptionIAMPolicy replaces the entire policy, SubscriptionIAMBinding manages all members for a specific role, and SubscriptionIAMMember adds individual members. The examples are intentionally small. Choose the resource that matches your permission management strategy.

Replace the entire IAM policy for a subscription

When you need complete control over subscription permissions, you can define the entire IAM policy and replace any existing access.

import * as pulumi from "@pulumi/pulumi";
import * as gcp from "@pulumi/gcp";

const admin = gcp.organizations.getIAMPolicy({
    bindings: [{
        role: "roles/editor",
        members: ["user:jane@example.com"],
    }],
});
const editor = new gcp.pubsub.SubscriptionIAMPolicy("editor", {
    subscription: "your-subscription-name",
    policyData: admin.then(admin => admin.policyData),
});

import pulumi
import pulumi_gcp as gcp

admin = gcp.organizations.get_iam_policy(bindings=[{
    "role": "roles/editor",
    "members": ["user:jane@example.com"],
}])
editor = gcp.pubsub.SubscriptionIAMPolicy("editor",
    subscription="your-subscription-name",
    policy_data=admin.policy_data)

package main

import (
	"github.com/pulumi/pulumi-gcp/sdk/v9/go/gcp/organizations"
	"github.com/pulumi/pulumi-gcp/sdk/v9/go/gcp/pubsub"
	"github.com/pulumi/pulumi/sdk/v3/go/pulumi"
)

func main() {
	pulumi.Run(func(ctx *pulumi.Context) error {
		admin, err := organizations.LookupIAMPolicy(ctx, &organizations.LookupIAMPolicyArgs{
			Bindings: []organizations.GetIAMPolicyBinding{
				{
					Role: "roles/editor",
					Members: []string{
						"user:jane@example.com",
					},
				},
			},
		}, nil)
		if err != nil {
			return err
		}
		_, err = pubsub.NewSubscriptionIAMPolicy(ctx, "editor", &pubsub.SubscriptionIAMPolicyArgs{
			Subscription: pulumi.String("your-subscription-name"),
			PolicyData:   pulumi.String(admin.PolicyData),
		})
		if err != nil {
			return err
		}
		return nil
	})
}

using System.Collections.Generic;
using System.Linq;
using Pulumi;
using Gcp = Pulumi.Gcp;

return await Deployment.RunAsync(() => 
{
    var admin = Gcp.Organizations.GetIAMPolicy.Invoke(new()
    {
        Bindings = new[]
        {
            new Gcp.Organizations.Inputs.GetIAMPolicyBindingInputArgs
            {
                Role = "roles/editor",
                Members = new[]
                {
                    "user:jane@example.com",
                },
            },
        },
    });

    var editor = new Gcp.PubSub.SubscriptionIAMPolicy("editor", new()
    {
        Subscription = "your-subscription-name",
        PolicyData = admin.Apply(getIAMPolicyResult => getIAMPolicyResult.PolicyData),
    });

});

package generated_program;

import com.pulumi.Context;
import com.pulumi.Pulumi;
import com.pulumi.core.Output;
import com.pulumi.gcp.organizations.OrganizationsFunctions;
import com.pulumi.gcp.organizations.inputs.GetIAMPolicyArgs;
import com.pulumi.gcp.pubsub.SubscriptionIAMPolicy;
import com.pulumi.gcp.pubsub.SubscriptionIAMPolicyArgs;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.io.File;
import java.nio.file.Files;
import java.nio.file.Paths;

public class App {
    public static void main(String[] args) {
        Pulumi.run(App::stack);
    }

    public static void stack(Context ctx) {
        final var admin = OrganizationsFunctions.getIAMPolicy(GetIAMPolicyArgs.builder()
            .bindings(GetIAMPolicyBindingArgs.builder()
                .role("roles/editor")
                .members("user:jane@example.com")
                .build())
            .build());

        var editor = new SubscriptionIAMPolicy("editor", SubscriptionIAMPolicyArgs.builder()
            .subscription("your-subscription-name")
            .policyData(admin.policyData())
            .build());

    }
}

resources:
  editor:
    type: gcp:pubsub:SubscriptionIAMPolicy
    properties:
      subscription: your-subscription-name
      policyData: ${admin.policyData}
variables:
  admin:
    fn::invoke:
      function: gcp:organizations:getIAMPolicy
      arguments:
        bindings:
          - role: roles/editor
            members:
              - user:jane@example.com

The SubscriptionIAMPolicy resource sets the complete IAM policy for the subscription. The policyData property comes from the getIAMPolicy data source, which defines bindings (role and member pairs). This resource is authoritative: it replaces any existing policy, removing permissions not listed in your configuration.

Grant a role to multiple members at once

Teams often assign the same role to several users or service accounts without affecting other roles.

import * as pulumi from "@pulumi/pulumi";
import * as gcp from "@pulumi/gcp";

const editor = new gcp.pubsub.SubscriptionIAMBinding("editor", {
    subscription: "your-subscription-name",
    role: "roles/editor",
    members: ["user:jane@example.com"],
});

import pulumi
import pulumi_gcp as gcp

editor = gcp.pubsub.SubscriptionIAMBinding("editor",
    subscription="your-subscription-name",
    role="roles/editor",
    members=["user:jane@example.com"])

package main

import (
	"github.com/pulumi/pulumi-gcp/sdk/v9/go/gcp/pubsub"
	"github.com/pulumi/pulumi/sdk/v3/go/pulumi"
)

func main() {
	pulumi.Run(func(ctx *pulumi.Context) error {
		_, err := pubsub.NewSubscriptionIAMBinding(ctx, "editor", &pubsub.SubscriptionIAMBindingArgs{
			Subscription: pulumi.String("your-subscription-name"),
			Role:         pulumi.String("roles/editor"),
			Members: pulumi.StringArray{
				pulumi.String("user:jane@example.com"),
			},
		})
		if err != nil {
			return err
		}
		return nil
	})
}

using System.Collections.Generic;
using System.Linq;
using Pulumi;
using Gcp = Pulumi.Gcp;

return await Deployment.RunAsync(() => 
{
    var editor = new Gcp.PubSub.SubscriptionIAMBinding("editor", new()
    {
        Subscription = "your-subscription-name",
        Role = "roles/editor",
        Members = new[]
        {
            "user:jane@example.com",
        },
    });

});

package generated_program;

import com.pulumi.Context;
import com.pulumi.Pulumi;
import com.pulumi.core.Output;
import com.pulumi.gcp.pubsub.SubscriptionIAMBinding;
import com.pulumi.gcp.pubsub.SubscriptionIAMBindingArgs;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.io.File;
import java.nio.file.Files;
import java.nio.file.Paths;

public class App {
    public static void main(String[] args) {
        Pulumi.run(App::stack);
    }

    public static void stack(Context ctx) {
        var editor = new SubscriptionIAMBinding("editor", SubscriptionIAMBindingArgs.builder()
            .subscription("your-subscription-name")
            .role("roles/editor")
            .members("user:jane@example.com")
            .build());

    }
}

resources:
  editor:
    type: gcp:pubsub:SubscriptionIAMBinding
    properties:
      subscription: your-subscription-name
      role: roles/editor
      members:
        - user:jane@example.com

The SubscriptionIAMBinding resource manages all members for a specific role. The members property lists everyone who should have this role. This resource is authoritative for the specified role: it replaces the member list for that role but preserves other roles on the subscription.

Add a single member to a role incrementally

When you want to grant access to one user without disturbing existing permissions, add members individually.

import * as pulumi from "@pulumi/pulumi";
import * as gcp from "@pulumi/gcp";

const editor = new gcp.pubsub.SubscriptionIAMMember("editor", {
    subscription: "your-subscription-name",
    role: "roles/editor",
    member: "user:jane@example.com",
});

import pulumi
import pulumi_gcp as gcp

editor = gcp.pubsub.SubscriptionIAMMember("editor",
    subscription="your-subscription-name",
    role="roles/editor",
    member="user:jane@example.com")

package main

import (
	"github.com/pulumi/pulumi-gcp/sdk/v9/go/gcp/pubsub"
	"github.com/pulumi/pulumi/sdk/v3/go/pulumi"
)

func main() {
	pulumi.Run(func(ctx *pulumi.Context) error {
		_, err := pubsub.NewSubscriptionIAMMember(ctx, "editor", &pubsub.SubscriptionIAMMemberArgs{
			Subscription: pulumi.String("your-subscription-name"),
			Role:         pulumi.String("roles/editor"),
			Member:       pulumi.String("user:jane@example.com"),
		})
		if err != nil {
			return err
		}
		return nil
	})
}

using System.Collections.Generic;
using System.Linq;
using Pulumi;
using Gcp = Pulumi.Gcp;

return await Deployment.RunAsync(() => 
{
    var editor = new Gcp.PubSub.SubscriptionIAMMember("editor", new()
    {
        Subscription = "your-subscription-name",
        Role = "roles/editor",
        Member = "user:jane@example.com",
    });

});

package generated_program;

import com.pulumi.Context;
import com.pulumi.Pulumi;
import com.pulumi.core.Output;
import com.pulumi.gcp.pubsub.SubscriptionIAMMember;
import com.pulumi.gcp.pubsub.SubscriptionIAMMemberArgs;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.io.File;
import java.nio.file.Files;
import java.nio.file.Paths;

public class App {
    public static void main(String[] args) {
        Pulumi.run(App::stack);
    }

    public static void stack(Context ctx) {
        var editor = new SubscriptionIAMMember("editor", SubscriptionIAMMemberArgs.builder()
            .subscription("your-subscription-name")
            .role("roles/editor")
            .member("user:jane@example.com")
            .build());

    }
}

resources:
  editor:
    type: gcp:pubsub:SubscriptionIAMMember
    properties:
      subscription: your-subscription-name
      role: roles/editor
      member: user:jane@example.com

The SubscriptionIAMMember resource adds one member to a role. The member property specifies a single identity. This resource is non-authoritative: it preserves other members already assigned to the role and other roles on the subscription.

Beyond these examples

These snippets focus on specific IAM management approaches: authoritative vs non-authoritative updates and policy-level, role-level, and member-level grants. They’re intentionally minimal rather than full access control configurations.

The examples reference pre-existing infrastructure such as Pub/Sub subscriptions (by name). They focus on IAM policy configuration rather than creating the subscriptions themselves.

To keep things focused, common IAM patterns are omitted, including:

Conditional IAM bindings (condition blocks)
Project-level configuration (project property)
Service account and group member types
Custom role definitions

These omissions are intentional: the goal is to illustrate how each IAM resource type works, not provide drop-in access control modules. See the Pub/Sub Subscription IAM Policy resource reference for all available configuration options.

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Frequently Asked Questions

Resource Selection & Compatibility

Can I use SubscriptionIAMPolicy with SubscriptionIAMBinding or SubscriptionIAMMember?

No, SubscriptionIAMPolicy cannot be used with SubscriptionIAMBinding or SubscriptionIAMMember as they will conflict over policy control.

Can I use SubscriptionIAMBinding and SubscriptionIAMMember together?

Yes, but only if they manage different roles. Using both for the same role will cause conflicts.

What's the difference between the three subscription IAM resources?

SubscriptionIAMPolicy is authoritative and replaces the entire policy. SubscriptionIAMBinding is authoritative per role, preserving other roles. SubscriptionIAMMember is non-authoritative, preserving other members for the same role.

Configuration & Usage

Which subscription IAM resource should I use?

Use SubscriptionIAMPolicy for full policy control, SubscriptionIAMBinding to manage all members for specific roles, or SubscriptionIAMMember to add individual members without affecting existing ones.

How do I generate the policyData for SubscriptionIAMPolicy?

Use the gcp.organizations.getIAMPolicy data source to generate the required policyData, as shown in the example.

Using a different cloud?

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