Grant roles using client libraries

Learn how to get started with the IAM methods from the Resource Manager API in your favorite programming language.

---

To follow step-by-step guidance for this task directly in the Google Cloud console, click Guide me:

Guide me

---

Before you begin

Create a Google Cloud project

For this quickstart, you need a new Google Cloud project.

Warning: If you use an existing project, then completing this quickstart will enable some users to temporarily access resources in that project.

1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.
2. Install the Google Cloud CLI.

3. To initialize the gcloud CLI, run the following command:

   gcloud init

4. Create or select a Google Cloud project.

   Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

   • Create a Google Cloud project:

     gcloud projects create PROJECT_ID

     Replace PROJECT_ID with a name for the Google Cloud project you are creating.

   • Select the Google Cloud project that you created:

     gcloud config set project PROJECT_ID

     Replace PROJECT_ID with your Google Cloud project name.

5. Enable the Resource Manager API:

   gcloud services enable cloudresourcemanager.googleapis.com

6. Create local authentication credentials for your user account:

   gcloud auth application-default login

7. Grant roles to your user account. Run the following command once for each of the following IAM roles: roles/resourcemanager.projectIamAdmin

   gcloud projects add-iam-policy-binding PROJECT_ID --member="user:USER_IDENTIFIER" --role=ROLE

   • Replace PROJECT_ID with your project ID.

   • Replace USER_IDENTIFIER with the identifier for your user account. For example, user:[e-mail].

   • Replace ROLE with each individual role.
8. Install the Google Cloud CLI.

9. To initialize the gcloud CLI, run the following command:

   gcloud init

10. Create or select a Google Cloud project.

    Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

    • Create a Google Cloud project:

      gcloud projects create PROJECT_ID

      Replace PROJECT_ID with a name for the Google Cloud project you are creating.

    • Select the Google Cloud project that you created:

      gcloud config set project PROJECT_ID

      Replace PROJECT_ID with your Google Cloud project name.

11. Enable the Resource Manager API:

    gcloud services enable cloudresourcemanager.googleapis.com

12. Create local authentication credentials for your user account:

    gcloud auth application-default login

13. Grant roles to your user account. Run the following command once for each of the following IAM roles: roles/resourcemanager.projectIamAdmin

    gcloud projects add-iam-policy-binding PROJECT_ID --member="user:USER_IDENTIFIER" --role=ROLE

    • Replace PROJECT_ID with your project ID.

    • Replace USER_IDENTIFIER with the identifier for your user account. For example, user:[e-mail].

    • Replace ROLE with each individual role.

Install the client library

C#

For more on setting up your C# development environment, refer to the C# Development Environment Setup Guide.

install-package Google.Apis.Iam.v1
install-package Google.Apis.CloudResourceManager.v1

Go

go get golang.org/x/oauth2/google
go get google.golang.org/api/cloudresourcemanager/v1

Java

For more on setting up your Java development environment, refer to the Java Development Environment Setup Guide.

If you are using Maven, add this to your pom.xml file.

<dependency>
  <groupId>com.google.apis</groupId>
  <artifactId>google-api-services-cloudresourcemanager</artifactId>
  <version>v3-rev20240128-2.0.0</version>
</dependency>
<dependency>
  <groupId>com.google.auth</groupId>
  <artifactId>google-auth-library-oauth2-http</artifactId>
</dependency>
<dependency>
  <groupId>com.google.http-client</groupId>
  <artifactId>google-http-client-jackson2</artifactId>
</dependency>
<dependency>
  <groupId>com.google.apis</groupId>
  <artifactId>google-api-services-iam</artifactId>
  <version>v1-rev20240118-2.0.0</version>
</dependency>

Python

For more on setting up your Python development environment, refer to the Python Development Environment Setup Guide.

pip install --upgrade google-api-python-client google-auth google-auth-httplib2

Read, modify, and write an allow policy

The code snippet in this quickstart does the following:

• Initializes the Resource Manager service, which manages Google Cloud projects.
• Reads the allow policy for your project.
• Modifies the allow policy by granting the Log Writer role (roles/logging.logWriter) to your Google Account.
• Writes the updated allow policy.
• Prints all the principals that have the Log Writer role (roles/logging.logWriter) at the project level.
• Revokes the Log Writer role.

Replace the following values before running the code snippet:

• your-project: The ID of your project.
• your-member: The email address for your user account. For example, user:[e-mail].

Note: The following snippet modifies access by getting, modifying, and setting the allow policy for the project. For more information on allow policies, see the IAM overview.

C#

To learn how to install and use the client library for Resource Manager, see Resource Manager client libraries. For more information, see the Resource Manager C# API reference documentation.

To authenticate to Resource Manager, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

using Google.Apis.Auth.OAuth2;
using Google.Apis.CloudResourceManager.v1;
using Google.Apis.CloudResourceManager.v1.Data;
using Google.Apis.Iam.v1;
using System;
using System.Collections.Generic;
using System.Linq;

public class QuickStart
{
    public static void Main(string[] args)
    {
        // TODO: Replace with your project ID
        var projectId = "your-project";
        // TODO: Replace with the ID of your principal.
        // For examples, see https://cloud.google.com/iam/docs/principal-identifiers
        var member = "your-principal";
        // Role to be granted
        var role = "roles/logging.logWriter";

        // Initialize service
        CloudResourceManagerService crmService = InitializeService();

        // Grant your principal the "Log Writer" role for your project
        AddBinding(crmService, projectId, member, role);

        // Get the project's policy and print all principals with the the "Log Writer" role
        var policy = GetPolicy(crmService, projectId);
        var binding = policy.Bindings.FirstOrDefault(x => x.Role == role);
        Console.WriteLine("Role: " + binding.Role);
        Console.Write("Members: ");
        foreach (var m in binding.Members)
        {
            Console.Write("[" + m + "] ");
        }
        Console.WriteLine();

        // Remove principal from the "Log Writer" role
        RemoveMember(crmService, projectId, member, role);
    }

    public static CloudResourceManagerService InitializeService()
    {
        // Get credentials
        var credential = GoogleCredential.GetApplicationDefault()
            .CreateScoped(IamService.Scope.CloudPlatform);

        // Create the Cloud Resource Manager service object
        CloudResourceManagerService crmService = new CloudResourceManagerService(
            new CloudResourceManagerService.Initializer
            {
                HttpClientInitializer = credential
            });

        return crmService;
    }

    public static Policy GetPolicy(CloudResourceManagerService crmService, String projectId)
    {
        // Get the project's policy by calling the
        // Cloud Resource Manager Projects API
        var policy = crmService.Projects.GetIamPolicy(
            new GetIamPolicyRequest(),
            projectId).Execute();
        return policy;
    }

    public static void SetPolicy(CloudResourceManagerService crmService, String projectId, Policy policy)
    {
        // Set the project's policy by calling the
        // Cloud Resource Manager Projects API
        crmService.Projects.SetIamPolicy(
           new SetIamPolicyRequest
           {
               Policy = policy
           }, projectId).Execute();
    }

    public static void AddBinding(
        CloudResourceManagerService crmService,
        string projectId,
        string member,
        string role)
    {
        // Get the project's policy
        var policy = GetPolicy(crmService, projectId);

        // Find binding in policy
        var binding = policy.Bindings.FirstOrDefault(x => x.Role == role);

        // If binding already exists, add principal to binding
        if (binding != null)
        {
            binding.Members.Add(member);
        }
        // If binding does not exist, add binding to policy
        else
        {
            binding = new Binding
            {
                Role = role,
                Members = new List<string> { member }
            };
            policy.Bindings.Add(binding);
        }

        // Set the updated policy
        SetPolicy(crmService, projectId, policy);
    }

    public static void RemoveMember(
        CloudResourceManagerService crmService,
        string projectId,
        string member,
        string role)
    {
        // Get the project's policy 
        var policy = GetPolicy(crmService, projectId);

        // Remove the principal from the role
        var binding = policy.Bindings.FirstOrDefault(x => x.Role == role);
        if (binding == null)
        {
            Console.WriteLine("Role does not exist in policy.");
        }
        else
        {
            if (binding.Members.Contains(member))
            {
                binding.Members.Remove(member);
            }
            else
            {
                Console.WriteLine("The member has not been granted this role.");
            }

            if (binding.Members.Count == 0)
            {
                policy.Bindings.Remove(binding);
            }
        }

        // Set the updated policy
        SetPolicy(crmService, projectId, policy);
    }
}

Go

To learn how to install and use the client library for Resource Manager, see Resource Manager client libraries. For more information, see the Resource Manager Go API reference documentation.

To authenticate to Resource Manager, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"strings"
	"time"

	"google.golang.org/api/cloudresourcemanager/v1"
)

func main() {
	// TODO: Add your project ID
	projectID := flag.String("project_id", "", "Cloud Project ID")
	// TODO: Add the ID of your principal.
	// For examples, see https://cloud.google.com/iam/docs/principal-identifiers
	member := flag.String("member_id", "", "Your principal ID")
	flag.Parse()

	// The role to be granted
	var role string = "roles/logging.logWriter"

	// Initializes the Cloud Resource Manager service
	ctx := context.Background()
	crmService, err := cloudresourcemanager.NewService(ctx)
	if err != nil {
		log.Fatalf("cloudresourcemanager.NewService: %v", err)
	}

	// Grants your principal the "Log writer" role for your project
	addBinding(crmService, *projectID, *member, role)

	// Gets the project's policy and prints all principals with the "Log Writer" role
	policy := getPolicy(crmService, *projectID)
	// Find the policy binding for role. Only one binding can have the role.
	var binding *cloudresourcemanager.Binding
	for _, b := range policy.Bindings {
		if b.Role == role {
			binding = b
			break
		}
	}
	fmt.Println("Role: ", binding.Role)
	fmt.Print("Members: ", strings.Join(binding.Members, ", "))

	// Removes member from the "Log writer" role
	removeMember(crmService, *projectID, *member, role)

}

// addBinding adds the principal to the project's IAM policy
func addBinding(crmService *cloudresourcemanager.Service, projectID, member, role string) {

	policy := getPolicy(crmService, projectID)

	// Find the policy binding for role. Only one binding can have the role.
	var binding *cloudresourcemanager.Binding
	for _, b := range policy.Bindings {
		if b.Role == role {
			binding = b
			break
		}
	}

	if binding != nil {
		// If the binding exists, adds the principal to the binding
		binding.Members = append(binding.Members, member)
	} else {
		// If the binding does not exist, adds a new binding to the policy
		binding = &cloudresourcemanager.Binding{
			Role:    role,
			Members: []string{member},
		}
		policy.Bindings = append(policy.Bindings, binding)
	}

	setPolicy(crmService, projectID, policy)

}

// removeMember removes the principal from the project's IAM policy
func removeMember(crmService *cloudresourcemanager.Service, projectID, member, role string) {

	policy := getPolicy(crmService, projectID)

	// Find the policy binding for role. Only one binding can have the role.
	var binding *cloudresourcemanager.Binding
	var bindingIndex int
	for i, b := range policy.Bindings {
		if b.Role == role {
			binding = b
			bindingIndex = i
			break
		}
	}

	// Order doesn't matter for bindings or members, so to remove, move the last item
	// into the removed spot and shrink the slice.
	if len(binding.Members) == 1 {
		// If the principal is the only member in the binding, removes the binding
		last := len(policy.Bindings) - 1
		policy.Bindings[bindingIndex] = policy.Bindings[last]
		policy.Bindings = policy.Bindings[:last]
	} else {
		// If there is more than one member in the binding, removes the principal
		var memberIndex int
		for i, mm := range binding.Members {
			if mm == member {
				memberIndex = i
			}
		}
		last := len(policy.Bindings[bindingIndex].Members) - 1
		binding.Members[memberIndex] = binding.Members[last]
		binding.Members = binding.Members[:last]
	}

	setPolicy(crmService, projectID, policy)

}

// getPolicy gets the project's IAM policy
func getPolicy(crmService *cloudresourcemanager.Service, projectID string) *cloudresourcemanager.Policy {

	ctx := context.Background()

	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
	defer cancel()
	request := new(cloudresourcemanager.GetIamPolicyRequest)
	policy, err := crmService.Projects.GetIamPolicy(projectID, request).Do()
	if err != nil {
		log.Fatalf("Projects.GetIamPolicy: %v", err)
	}

	return policy
}

// setPolicy sets the project's IAM policy
func setPolicy(crmService *cloudresourcemanager.Service, projectID string, policy *cloudresourcemanager.Policy) {

	ctx := context.Background()

	ctx, cancel := context.WithTimeout(ctx, time.Second*10)
	defer cancel()
	request := new(cloudresourcemanager.SetIamPolicyRequest)
	request.Policy = policy
	policy, err := crmService.Projects.SetIamPolicy(projectID, request).Do()
	if err != nil {
		log.Fatalf("Projects.SetIamPolicy: %v", err)
	}
}

Java

To learn how to install and use the client library for Resource Manager, see Resource Manager client libraries. For more information, see the Resource Manager Java API reference documentation.

To authenticate to Resource Manager, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import com.google.cloud.iam.admin.v1.IAMClient;
import com.google.iam.admin.v1.ServiceAccountName;
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.protobuf.FieldMask;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Quickstart {

  public static void main(String[] args) throws IOException {
    // TODO: Replace with your project ID.
    String projectId = "your-project";
    // TODO: Replace with your service account name.
    String serviceAccount = "your-service-account";
    // TODO: Replace with the ID of your member in the form "user:[e-mail]"
    String member = "your-member";
    // The role to be granted.
    String role = "roles/logging.logWriter";

    quickstart(projectId, serviceAccount, member, role);
  }

  // Creates new policy and adds binding.
  // Checks if changes are present and removes policy.
  public static void quickstart(String projectId, String serviceAccount,
                                String member, String role) throws IOException {

    // Construct the service account email.
    // You can modify the ".iam.gserviceaccount.com" to match the name of the service account
    // to use for authentication.
    serviceAccount = serviceAccount + "@" + projectId + ".iam.gserviceaccount.com";

    // Initialize client that will be used to send requests.
    // This client only needs to be created once, and can be reused for multiple requests.
    try (IAMClient iamClient = IAMClient.create()) {

      // Grants your member the "Log writer" role for your project.
      addBinding(iamClient, projectId, serviceAccount, member, role);

      // Get the project's policy and print all members with the "Log Writer" role
      Policy policy = getPolicy(iamClient, projectId, serviceAccount);

      Binding binding = null;
      List<Binding> bindings = policy.getBindingsList();

      for (Binding b : bindings) {
        if (b.getRole().equals(role)) {
          binding = b;
          break;
        }
      }

      System.out.println("Role: " + binding.getRole());
      System.out.print("Members: ");

      for (String m : binding.getMembersList()) {
        System.out.print("[" + m + "] ");
      }
      System.out.println();

      // Removes member from the "Log writer" role.
      removeMember(iamClient, projectId, serviceAccount, member, role);
    }
  }

  public static void addBinding(IAMClient iamClient, String projectId, String serviceAccount,
                                String member, String role) {
    // Gets the project's policy.
    Policy policy = getPolicy(iamClient, projectId, serviceAccount);

    // If policy is not retrieved, return early.
    if (policy == null) {
      return;
    }

    Policy.Builder updatedPolicy = policy.toBuilder();

    // Get the binding if present in the policy.
    Binding binding = null;
    for (Binding b : updatedPolicy.getBindingsList()) {
      if (b.getRole().equals(role)) {
        binding = b;
        break;
      }
    }

    if (binding != null) {
      // If binding already exists, adds member to binding.
      binding.getMembersList().add(member);
    } else {
      // If binding does not exist, adds binding to policy.
      binding = Binding.newBuilder()
              .setRole(role)
              .addMembers(member)
              .build();
      updatedPolicy.addBindings(binding);
    }

    // Sets the updated policy.
    setPolicy(iamClient, projectId, serviceAccount, updatedPolicy.build());
  }

  public static void removeMember(IAMClient iamClient, String projectId, String serviceAccount,
                                  String member, String role) {
    // Gets the project's policy.
    Policy.Builder policy = getPolicy(iamClient, projectId, serviceAccount).toBuilder();

    // Removes the member from the role.
    Binding binding = null;
    for (Binding b : policy.getBindingsList()) {
      if (b.getRole().equals(role)) {
        binding = b;
        break;
      }
    }

    if (binding != null && binding.getMembersList().contains(member)) {
      List<String> newMemberList = new ArrayList<>(binding.getMembersList());
      newMemberList.remove(member);

      Binding newBinding = binding.toBuilder().clearMembers()
              .addAllMembers(newMemberList)
              .build();
      List<Binding> newBindingList = new ArrayList<>(policy.getBindingsList());
      newBindingList.remove(binding);

      if (!newBinding.getMembersList().isEmpty()) {
        newBindingList.add(newBinding);
      }

      policy.clearBindings()
              .addAllBindings(newBindingList);
    }

    // Sets the updated policy.
    setPolicy(iamClient, projectId, serviceAccount, policy.build());
  }

  public static Policy getPolicy(IAMClient iamClient, String projectId, String serviceAccount) {
    // Gets the project's policy by calling the
    // IAMClient API.
    GetIamPolicyRequest request = GetIamPolicyRequest.newBuilder()
            .setResource(ServiceAccountName.of(projectId, serviceAccount).toString())
            .build();
    return iamClient.getIamPolicy(request);
  }

  private static void setPolicy(IAMClient iamClient, String projectId,
                                String serviceAccount, Policy policy) {
    List<String> paths = Arrays.asList("bindings", "etag");
    // Sets a project's policy.
    SetIamPolicyRequest request = SetIamPolicyRequest.newBuilder()
            .setResource(ServiceAccountName.of(projectId, serviceAccount).toString())
            .setPolicy(policy)
            // A FieldMask specifying which fields of the policy to modify. Only
            // the fields in the mask will be modified. If no mask is provided, the
            // following default mask is used:
            // `paths: "bindings, etag"`
            .setUpdateMask(FieldMask.newBuilder().addAllPaths(paths).build())
            .build();
    iamClient.setIamPolicy(request);
  }
}

Python

To learn how to install and use the client library for Resource Manager, see Resource Manager client libraries. For more information, see the Resource Manager Python API reference documentation.

To authenticate to Resource Manager, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

from google.cloud import resourcemanager_v3
from google.iam.v1 import iam_policy_pb2, policy_pb2


def quickstart(project_id: str, member: str) -> None:
    """Gets a policy, adds a member, prints their permissions, and removes the member.

    project_id: ID or number of the Google Cloud project you want to use.
    member: The principals requesting the access.
    """

    # Role to be granted.
    role = "roles/logging.logWriter"
    crm_service = resourcemanager_v3.ProjectsClient()

    # Grants your member the 'Log Writer' role for the project.
    modify_policy_add_role(crm_service, project_id, role, member)

    # Gets the project's policy and prints all members with the 'Log Writer' role.
    policy = get_policy(crm_service, project_id)
    binding = next(b for b in policy.bindings if b.role == role)
    print(f"Role: {(binding.role)}")
    print("Members: ")
    for m in binding.members:
        print(f"[{m}]")

    # Removes the member from the 'Log Writer' role.
    modify_policy_remove_member(crm_service, project_id, role, member)


def get_policy(
    crm_service: resourcemanager_v3.ProjectsClient, project_id: str
) -> policy_pb2.Policy:
    """Gets IAM policy for a project."""

    request = iam_policy_pb2.GetIamPolicyRequest()
    request.resource = f"projects/{project_id}"

    policy = crm_service.get_iam_policy(request)
    return policy


def set_policy(
    crm_service: resourcemanager_v3.ProjectsClient,
    project_id: str,
    policy: policy_pb2.Policy,
) -> None:
    """Adds a new role binding to a policy."""

    request = iam_policy_pb2.SetIamPolicyRequest()
    request.resource = f"projects/{project_id}"
    request.policy.CopyFrom(policy)

    crm_service.set_iam_policy(request)


def modify_policy_add_role(
    crm_service: resourcemanager_v3.ProjectsClient,
    project_id: str,
    role: str,
    member: str,
) -> None:
    """Adds a new role binding to a policy."""

    policy = get_policy(crm_service, project_id)

    for bind in policy.bindings:
        if bind.role == role:
            bind.members.append(member)
            break
    else:
        binding = policy_pb2.Binding()
        binding.role = role
        binding.members.append(member)
        policy.bindings.append(binding)

    set_policy(crm_service, project_id, policy)


def modify_policy_remove_member(
    crm_service: resourcemanager_v3.ProjectsClient,
    project_id: str,
    role: str,
    member: str,
) -> None:
    """Removes a  member from a role binding."""

    policy = get_policy(crm_service, project_id)

    for bind in policy.bindings:
        if bind.role == role:
            if member in bind.members:
                bind.members.remove(member)
            break

    set_policy(crm_service, project_id, policy)


if __name__ == "__main__":
    # TODO: replace with your project ID
    project_id = "your-project-id"
    # TODO: Replace with the ID of your member in the form 'user:[e-mail]'.
    member = "your-member"
    quickstart(project_id, member)

Congratulations! You used the IAM methods in the Resource Manager API to modify access for a project.

How did it go?

It worked!

Great! What did you like about the quickstart? What could we have done better? Let us know!.

I got stuck.

We're sorry to hear that. Let us know what went wrong. We'll want to fix it.

Clean up

1. Optional: Revoke the authentication credentials that you created, and delete the local credential file.

   gcloud auth application-default revoke

2. Optional: Revoke credentials from the gcloud CLI.

   gcloud auth revoke

What's next

• Read about how IAM works.
• Learn more about granting, changing, and revoking access.
• Troubleshoot access issues with the Policy Troubleshooter.