Manage GCP Backend Service IAM Policies

The gcp:compute/backendServiceIamPolicy:BackendServiceIamPolicy resource, part of the Pulumi GCP provider, manages IAM access control for Compute Engine backend services. This guide focuses on four capabilities: authoritative policy replacement, role-based member lists, non-authoritative member grants, and time-based access with IAM Conditions.

Backend service IAM resources reference existing backend services by name and project. The examples are intentionally small. Combine them with your own backend service infrastructure and organizational access patterns.

Replace the entire IAM policy for a backend service

When you need complete control over who can access a backend service, you can set the entire IAM policy at once.

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

const admin = gcp.organizations.getIAMPolicy({
    bindings: [{
        role: "roles/compute.admin",
        members: ["user:jane@example.com"],
    }],
});
const policy = new gcp.compute.BackendServiceIamPolicy("policy", {
    project: _default.project,
    name: _default.name,
    policyData: admin.then(admin => admin.policyData),
});

import pulumi
import pulumi_gcp as gcp

admin = gcp.organizations.get_iam_policy(bindings=[{
    "role": "roles/compute.admin",
    "members": ["user:jane@example.com"],
}])
policy = gcp.compute.BackendServiceIamPolicy("policy",
    project=default["project"],
    name=default["name"],
    policy_data=admin.policy_data)

package main

import (
	"github.com/pulumi/pulumi-gcp/sdk/v9/go/gcp/compute"
	"github.com/pulumi/pulumi-gcp/sdk/v9/go/gcp/organizations"
	"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/compute.admin",
					Members: []string{
						"user:jane@example.com",
					},
				},
			},
		}, nil)
		if err != nil {
			return err
		}
		_, err = compute.NewBackendServiceIamPolicy(ctx, "policy", &compute.BackendServiceIamPolicyArgs{
			Project:    pulumi.Any(_default.Project),
			Name:       pulumi.Any(_default.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/compute.admin",
                Members = new[]
                {
                    "user:jane@example.com",
                },
            },
        },
    });

    var policy = new Gcp.Compute.BackendServiceIamPolicy("policy", new()
    {
        Project = @default.Project,
        Name = @default.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.compute.BackendServiceIamPolicy;
import com.pulumi.gcp.compute.BackendServiceIamPolicyArgs;
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/compute.admin")
                .members("user:jane@example.com")
                .build())
            .build());

        var policy = new BackendServiceIamPolicy("policy", BackendServiceIamPolicyArgs.builder()
            .project(default_.project())
            .name(default_.name())
            .policyData(admin.policyData())
            .build());

    }
}

resources:
  policy:
    type: gcp:compute:BackendServiceIamPolicy
    properties:
      project: ${default.project}
      name: ${default.name}
      policyData: ${admin.policyData}
variables:
  admin:
    fn::invoke:
      function: gcp:organizations:getIAMPolicy
      arguments:
        bindings:
          - role: roles/compute.admin
            members:
              - user:jane@example.com

The BackendServiceIamPolicy resource is authoritative: it replaces all existing IAM bindings on the backend service. The policyData comes from getIAMPolicy, which constructs the policy document from bindings. Each binding specifies a role and the members who receive that role.

Grant a role to multiple members at once

Teams often need to grant the same role to several users or service accounts without managing each member individually.

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

const binding = new gcp.compute.BackendServiceIamBinding("binding", {
    project: _default.project,
    name: _default.name,
    role: "roles/compute.admin",
    members: ["user:jane@example.com"],
});

import pulumi
import pulumi_gcp as gcp

binding = gcp.compute.BackendServiceIamBinding("binding",
    project=default["project"],
    name=default["name"],
    role="roles/compute.admin",
    members=["user:jane@example.com"])

package main

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

func main() {
	pulumi.Run(func(ctx *pulumi.Context) error {
		_, err := compute.NewBackendServiceIamBinding(ctx, "binding", &compute.BackendServiceIamBindingArgs{
			Project: pulumi.Any(_default.Project),
			Name:    pulumi.Any(_default.Name),
			Role:    pulumi.String("roles/compute.admin"),
			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 binding = new Gcp.Compute.BackendServiceIamBinding("binding", new()
    {
        Project = @default.Project,
        Name = @default.Name,
        Role = "roles/compute.admin",
        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.compute.BackendServiceIamBinding;
import com.pulumi.gcp.compute.BackendServiceIamBindingArgs;
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 binding = new BackendServiceIamBinding("binding", BackendServiceIamBindingArgs.builder()
            .project(default_.project())
            .name(default_.name())
            .role("roles/compute.admin")
            .members("user:jane@example.com")
            .build());

    }
}

resources:
  binding:
    type: gcp:compute:BackendServiceIamBinding
    properties:
      project: ${default.project}
      name: ${default.name}
      role: roles/compute.admin
      members:
        - user:jane@example.com

The BackendServiceIamBinding resource is authoritative for a specific role: it replaces all members for that role while preserving other roles on the backend service. The members array lists all identities that should have this role. If you later remove a member from the array, they lose access.

Add a single member to a role incrementally

When multiple teams manage access to the same backend service, non-authoritative member grants let you add permissions without affecting other members.

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

const member = new gcp.compute.BackendServiceIamMember("member", {
    project: _default.project,
    name: _default.name,
    role: "roles/compute.admin",
    member: "user:jane@example.com",
});

import pulumi
import pulumi_gcp as gcp

member = gcp.compute.BackendServiceIamMember("member",
    project=default["project"],
    name=default["name"],
    role="roles/compute.admin",
    member="user:jane@example.com")

package main

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

func main() {
	pulumi.Run(func(ctx *pulumi.Context) error {
		_, err := compute.NewBackendServiceIamMember(ctx, "member", &compute.BackendServiceIamMemberArgs{
			Project: pulumi.Any(_default.Project),
			Name:    pulumi.Any(_default.Name),
			Role:    pulumi.String("roles/compute.admin"),
			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 member = new Gcp.Compute.BackendServiceIamMember("member", new()
    {
        Project = @default.Project,
        Name = @default.Name,
        Role = "roles/compute.admin",
        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.compute.BackendServiceIamMember;
import com.pulumi.gcp.compute.BackendServiceIamMemberArgs;
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 member = new BackendServiceIamMember("member", BackendServiceIamMemberArgs.builder()
            .project(default_.project())
            .name(default_.name())
            .role("roles/compute.admin")
            .member("user:jane@example.com")
            .build());

    }
}

resources:
  member:
    type: gcp:compute:BackendServiceIamMember
    properties:
      project: ${default.project}
      name: ${default.name}
      role: roles/compute.admin
      member: user:jane@example.com

The BackendServiceIamMember resource is non-authoritative: it adds one member to a role without replacing existing members. Multiple teams can use separate BackendServiceIamMember resources to grant the same role to different users. This resource preserves other members for the same role.

Set time-based access with IAM Conditions

Temporary access grants expire automatically when you use IAM Conditions, eliminating the need to manually revoke permissions.

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

const admin = gcp.organizations.getIAMPolicy({
    bindings: [{
        role: "roles/compute.admin",
        members: ["user:jane@example.com"],
        condition: {
            title: "expires_after_2019_12_31",
            description: "Expiring at midnight of 2019-12-31",
            expression: "request.time < timestamp(\"2020-01-01T00:00:00Z\")",
        },
    }],
});
const policy = new gcp.compute.BackendServiceIamPolicy("policy", {
    project: _default.project,
    name: _default.name,
    policyData: admin.then(admin => admin.policyData),
});

import pulumi
import pulumi_gcp as gcp

admin = gcp.organizations.get_iam_policy(bindings=[{
    "role": "roles/compute.admin",
    "members": ["user:jane@example.com"],
    "condition": {
        "title": "expires_after_2019_12_31",
        "description": "Expiring at midnight of 2019-12-31",
        "expression": "request.time < timestamp(\"2020-01-01T00:00:00Z\")",
    },
}])
policy = gcp.compute.BackendServiceIamPolicy("policy",
    project=default["project"],
    name=default["name"],
    policy_data=admin.policy_data)

package main

import (
	"github.com/pulumi/pulumi-gcp/sdk/v9/go/gcp/compute"
	"github.com/pulumi/pulumi-gcp/sdk/v9/go/gcp/organizations"
	"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/compute.admin",
					Members: []string{
						"user:jane@example.com",
					},
					Condition: {
						Title:       "expires_after_2019_12_31",
						Description: pulumi.StringRef("Expiring at midnight of 2019-12-31"),
						Expression:  "request.time < timestamp(\"2020-01-01T00:00:00Z\")",
					},
				},
			},
		}, nil)
		if err != nil {
			return err
		}
		_, err = compute.NewBackendServiceIamPolicy(ctx, "policy", &compute.BackendServiceIamPolicyArgs{
			Project:    pulumi.Any(_default.Project),
			Name:       pulumi.Any(_default.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/compute.admin",
                Members = new[]
                {
                    "user:jane@example.com",
                },
                Condition = new Gcp.Organizations.Inputs.GetIAMPolicyBindingConditionInputArgs
                {
                    Title = "expires_after_2019_12_31",
                    Description = "Expiring at midnight of 2019-12-31",
                    Expression = "request.time < timestamp(\"2020-01-01T00:00:00Z\")",
                },
            },
        },
    });

    var policy = new Gcp.Compute.BackendServiceIamPolicy("policy", new()
    {
        Project = @default.Project,
        Name = @default.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.compute.BackendServiceIamPolicy;
import com.pulumi.gcp.compute.BackendServiceIamPolicyArgs;
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/compute.admin")
                .members("user:jane@example.com")
                .condition(GetIAMPolicyBindingConditionArgs.builder()
                    .title("expires_after_2019_12_31")
                    .description("Expiring at midnight of 2019-12-31")
                    .expression("request.time < timestamp(\"2020-01-01T00:00:00Z\")")
                    .build())
                .build())
            .build());

        var policy = new BackendServiceIamPolicy("policy", BackendServiceIamPolicyArgs.builder()
            .project(default_.project())
            .name(default_.name())
            .policyData(admin.policyData())
            .build());

    }
}

resources:
  policy:
    type: gcp:compute:BackendServiceIamPolicy
    properties:
      project: ${default.project}
      name: ${default.name}
      policyData: ${admin.policyData}
variables:
  admin:
    fn::invoke:
      function: gcp:organizations:getIAMPolicy
      arguments:
        bindings:
          - role: roles/compute.admin
            members:
              - user:jane@example.com
            condition:
              title: expires_after_2019_12_31
              description: Expiring at midnight of 2019-12-31
              expression: request.time < timestamp("2020-01-01T00:00:00Z")

The condition block adds time-based expiration to any IAM resource. The expression uses CEL (Common Expression Language) to define when access expires. Here, the timestamp function sets a hard cutoff at midnight on January 1, 2020. IAM Conditions have known limitations; review Google Cloud’s documentation if you encounter issues.

Beyond these examples

These snippets focus on specific IAM management features: authoritative vs non-authoritative access control, role-based and member-based grants, and time-based access with IAM Conditions. They’re intentionally minimal rather than full access control systems.

The examples reference pre-existing infrastructure such as backend services (by name and project). They focus on configuring IAM bindings rather than provisioning the backend services themselves.

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

Combining Policy with Binding/Member resources (causes conflicts)
Custom IAM roles (examples use predefined roles only)
Condition expressions beyond time-based expiration
Project-level or organization-level IAM inheritance

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

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Frequently Asked Questions

Resource Selection & Conflicts

What's the difference between IamPolicy, IamBinding, and IamMember?

BackendServiceIamPolicy is authoritative and replaces the entire IAM policy. BackendServiceIamBinding is authoritative for a specific role, managing all members for that role while preserving other roles. BackendServiceIamMember is non-authoritative, adding individual members without affecting other members or roles.

Which IAM resources can I use together?

Never use BackendServiceIamPolicy with BackendServiceIamBinding or BackendServiceIamMember, as they will conflict. You can use BackendServiceIamBinding and BackendServiceIamMember together only if they manage different roles.

Why am I getting IAM policy conflicts?

Conflicts occur when mixing BackendServiceIamPolicy (which replaces the entire policy) with BackendServiceIamBinding or BackendServiceIamMember (which make incremental changes). Choose one approach and stick with it.

IAM Conditions

How do I implement time-based or conditional access?

Add a condition block with title, description, and expression fields. The expression uses CEL syntax, such as request.time < timestamp("2020-01-01T00:00:00Z") for time-based expiration.

What are the limitations of IAM Conditions?

IAM Conditions are supported but have known limitations. Review GCP’s IAM Conditions documentation if you encounter issues with conditional access policies.

Using a different cloud?

Explore security guides for other cloud providers:

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