Manage GCP Region Backend Service IAM Bindings

The gcp:compute/regionBackendServiceIamBinding:RegionBackendServiceIamBinding resource, part of the Pulumi GCP provider, manages IAM role bindings for regional backend services. It grants roles to lists of members while preserving other roles in the policy. This guide focuses on three capabilities: binding roles to multiple members, adding individual members non-authoritatively, and applying time-based access with IAM Conditions.

IAM bindings reference existing regional backend services and rely on project and region configuration. The examples are intentionally small. Combine them with your own backend service infrastructure and access policies.

Grant a role to multiple members at once

When managing backend service access, teams often need to assign the same role to multiple users or service accounts simultaneously.

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

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

import pulumi
import pulumi_gcp as gcp

binding = gcp.compute.RegionBackendServiceIamBinding("binding",
    project=default["project"],
    region=default["region"],
    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.NewRegionBackendServiceIamBinding(ctx, "binding", &compute.RegionBackendServiceIamBindingArgs{
			Project: pulumi.Any(_default.Project),
			Region:  pulumi.Any(_default.Region),
			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.RegionBackendServiceIamBinding("binding", new()
    {
        Project = @default.Project,
        Region = @default.Region,
        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.RegionBackendServiceIamBinding;
import com.pulumi.gcp.compute.RegionBackendServiceIamBindingArgs;
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 RegionBackendServiceIamBinding("binding", RegionBackendServiceIamBindingArgs.builder()
            .project(default_.project())
            .region(default_.region())
            .name(default_.name())
            .role("roles/compute.admin")
            .members("user:jane@example.com")
            .build());

    }
}

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

The RegionBackendServiceIamBinding resource is authoritative for the specified role. The members array lists all identities that receive the role; any members not in this list lose access to that role. The name, region, and project properties identify which backend service to modify.

Add a single member to a role incrementally

When onboarding new team members or service accounts, you can grant access without affecting existing permissions.

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

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

import pulumi
import pulumi_gcp as gcp

member = gcp.compute.RegionBackendServiceIamMember("member",
    project=default["project"],
    region=default["region"],
    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.NewRegionBackendServiceIamMember(ctx, "member", &compute.RegionBackendServiceIamMemberArgs{
			Project: pulumi.Any(_default.Project),
			Region:  pulumi.Any(_default.Region),
			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.RegionBackendServiceIamMember("member", new()
    {
        Project = @default.Project,
        Region = @default.Region,
        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.RegionBackendServiceIamMember;
import com.pulumi.gcp.compute.RegionBackendServiceIamMemberArgs;
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 RegionBackendServiceIamMember("member", RegionBackendServiceIamMemberArgs.builder()
            .project(default_.project())
            .region(default_.region())
            .name(default_.name())
            .role("roles/compute.admin")
            .member("user:jane@example.com")
            .build());

    }
}

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

The RegionBackendServiceIamMember resource is non-authoritative. It adds one member to a role without removing other members who already have that role. Use this when you need to grant access incrementally rather than managing the complete member list.

Apply time-based access with IAM Conditions

Temporary access grants, such as contractor permissions or time-limited testing, require automatic expiration.

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

const binding = new gcp.compute.RegionBackendServiceIamBinding("binding", {
    project: _default.project,
    region: _default.region,
    name: _default.name,
    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\")",
    },
});

import pulumi
import pulumi_gcp as gcp

binding = gcp.compute.RegionBackendServiceIamBinding("binding",
    project=default["project"],
    region=default["region"],
    name=default["name"],
    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\")",
    })

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.NewRegionBackendServiceIamBinding(ctx, "binding", &compute.RegionBackendServiceIamBindingArgs{
			Project: pulumi.Any(_default.Project),
			Region:  pulumi.Any(_default.Region),
			Name:    pulumi.Any(_default.Name),
			Role:    pulumi.String("roles/compute.admin"),
			Members: pulumi.StringArray{
				pulumi.String("user:jane@example.com"),
			},
			Condition: &compute.RegionBackendServiceIamBindingConditionArgs{
				Title:       pulumi.String("expires_after_2019_12_31"),
				Description: pulumi.String("Expiring at midnight of 2019-12-31"),
				Expression:  pulumi.String("request.time < timestamp(\"2020-01-01T00:00:00Z\")"),
			},
		})
		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.RegionBackendServiceIamBinding("binding", new()
    {
        Project = @default.Project,
        Region = @default.Region,
        Name = @default.Name,
        Role = "roles/compute.admin",
        Members = new[]
        {
            "user:jane@example.com",
        },
        Condition = new Gcp.Compute.Inputs.RegionBackendServiceIamBindingConditionArgs
        {
            Title = "expires_after_2019_12_31",
            Description = "Expiring at midnight of 2019-12-31",
            Expression = "request.time < timestamp(\"2020-01-01T00:00:00Z\")",
        },
    });

});

package generated_program;

import com.pulumi.Context;
import com.pulumi.Pulumi;
import com.pulumi.core.Output;
import com.pulumi.gcp.compute.RegionBackendServiceIamBinding;
import com.pulumi.gcp.compute.RegionBackendServiceIamBindingArgs;
import com.pulumi.gcp.compute.inputs.RegionBackendServiceIamBindingConditionArgs;
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 RegionBackendServiceIamBinding("binding", RegionBackendServiceIamBindingArgs.builder()
            .project(default_.project())
            .region(default_.region())
            .name(default_.name())
            .role("roles/compute.admin")
            .members("user:jane@example.com")
            .condition(RegionBackendServiceIamBindingConditionArgs.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());

    }
}

resources:
  binding:
    type: gcp:compute:RegionBackendServiceIamBinding
    properties:
      project: ${default.project}
      region: ${default.region}
      name: ${default.name}
      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 temporal logic to the binding. The expression property uses CEL (Common Expression Language) to define when access is valid. Here, the condition checks that the request time is before midnight on January 1, 2020. The title and description provide human-readable context for the condition.

Beyond these examples

These snippets focus on specific IAM binding features: role-based bindings and member grants, and IAM Conditions for time-based access. They’re intentionally minimal rather than complete access control policies.

The examples reference pre-existing infrastructure such as regional backend services, and GCP project and region configuration. They focus on configuring IAM bindings rather than provisioning the backend services themselves.

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

Full policy replacement (RegionBackendServiceIamPolicy)
Custom role definitions and formatting
Federated identity and workload identity pool configuration
Conflict resolution between Policy, Binding, and Member resources

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

Let's manage GCP Region Backend Service IAM Bindings

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Frequently Asked Questions

Resource Selection & Conflicts

What's the difference between Policy, Binding, and Member resources?

Three resources manage IAM for Regional Backend Services:

Policy - Authoritative, replaces the entire IAM policy
Binding - Authoritative for a specific role, manages all members for that role while preserving other roles
Member - Non-authoritative, adds individual members without affecting other members or roles

Can I use Policy together with Binding or Member resources?

No, RegionBackendServiceIamPolicy cannot be used with RegionBackendServiceIamBinding or RegionBackendServiceIamMember as they will conflict over policy control.

Can I use Binding and Member resources together?

Yes, but only if they manage different roles. Using both RegionBackendServiceIamBinding and RegionBackendServiceIamMember for the same role causes conflicts.

IAM Configuration

How do I format member identities in the members array?

The members array supports these formats:

user:{email} - Specific Google account (e.g., user:alice@gmail.com)
serviceAccount:{email} - Service account (e.g., serviceAccount:my-app@appspot.gserviceaccount.com)
group:{email} - Google group (e.g., group:admins@example.com)
domain:{domain} - All users in a G Suite domain (e.g., domain:example.com)
allUsers - Anyone on the internet
allAuthenticatedUsers - Anyone with a Google account
projectOwner:projectid, projectEditor:projectid, projectViewer:projectid - Project-level roles
Federated identities using principal:// format

What format do custom roles require?

Custom roles must use the format [projects|organizations]/{parent-name}/roles/{role-name}. For example, projects/my-project/roles/my-custom-role or organizations/my-org/roles/my-custom-role.

What properties are immutable after creation?

The name, project, region, role, and condition properties cannot be changed after creation. Modifying these requires recreating the resource.

IAM Conditions

How do I add time-based or conditional access restrictions?

Use the condition property with title, description, and expression fields. For example, to expire access at a specific time: expression: "request.time < timestamp(\"2020-01-01T00:00:00Z\")".

Are there limitations when using IAM Conditions?

Yes, IAM Conditions have known limitations. Review the GCP documentation on IAM Conditions limitations if you encounter issues with conditional access.

Resource Identification

What happens if I don't specify project or region?

If project isn’t specified, it’s parsed from the parent resource identifier or defaults to the provider project. If region isn’t specified, it’s parsed from the parent identifier or defaults to the provider region.

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