Write an allow policy by using client libraries

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

---

For step-by-step guidance on this task directly in Cloud console, click Guide me:

Guide me

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The following sections take you through the same steps as clicking 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. In the Google Cloud console, on the project selector page, click Create project to begin creating a new Google Cloud project.

   Go to project selector

3. Enable the Resource Manager API.

   Enable the API

4. Create a service account:

   1. In the Cloud console, go to the Create service account page.

      Go to Create service account
   2. Select your project.

   3. In the Service account name field, enter a name. The Cloud console fills in the Service account ID field based on this name.

      In the Service account description field, enter a description. For example, Service account for quickstart.

   4. Click Create and continue.

   5. To provide access to your project, grant the following role(s) to your service account: Project IAM Admin .

      In the Select a role list, select a role.

      For additional roles, click Add another role and add each additional role.

      Note: The Role field affects which resources your service account can access in your project. You can revoke these roles or grant additional roles later. In production environments, do not grant the Owner, Editor, or Viewer roles. Instead, grant a predefined role or custom role that meets your needs.
   6. Click Continue.

   7. Click Done to finish creating the service account.

      Do not close your browser window. You will use it in the next step.

5. Create a service account key:

   1. In the Cloud console, click the email address for the service account that you created.
   2. Click Keys.
   3. Click Add key, and then click Create new key.
   4. Click Create. A JSON key file is downloaded to your computer.
   5. Click Close.

6. Set the environment variable GOOGLE_APPLICATION_CREDENTIALS to the path of the JSON file that contains your service account key. This variable only applies to your current shell session, so if you open a new session, set the variable again.

   Example: Linux or macOS

   export GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"

   Replace KEY_PATH with the path of the JSON file that contains your service account key.

   For example:

   export GOOGLE_APPLICATION_CREDENTIALS="/home/user/Downloads/service-account-file.json"

   Example: Windows

   For PowerShell:

   $env:GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"

   Replace KEY_PATH with the path of the JSON file that contains your service account key.

   For example:

   $env:GOOGLE_APPLICATION_CREDENTIALS="C:\Users\username\Downloads\service-account-file.json"

   For command prompt:

   set GOOGLE_APPLICATION_CREDENTIALS=KEY_PATH

   Replace KEY_PATH with the path of the JSON file that contains your service account key.

7. In the Google Cloud console, on the project selector page, click Create project to begin creating a new Google Cloud project.

   Go to project selector

8. Enable the Resource Manager API.

   Enable the API

9. Create a service account:

   1. In the Cloud console, go to the Create service account page.

      Go to Create service account
   2. Select your project.

   3. In the Service account name field, enter a name. The Cloud console fills in the Service account ID field based on this name.

      In the Service account description field, enter a description. For example, Service account for quickstart.

   4. Click Create and continue.

   5. To provide access to your project, grant the following role(s) to your service account: Project IAM Admin .

      In the Select a role list, select a role.

      For additional roles, click Add another role and add each additional role.

      Note: The Role field affects which resources your service account can access in your project. You can revoke these roles or grant additional roles later. In production environments, do not grant the Owner, Editor, or Viewer roles. Instead, grant a predefined role or custom role that meets your needs.
   6. Click Continue.

   7. Click Done to finish creating the service account.

      Do not close your browser window. You will use it in the next step.

10. Create a service account key:

    1. In the Cloud console, click the email address for the service account that you created.
    2. Click Keys.
    3. Click Add key, and then click Create new key.
    4. Click Create. A JSON key file is downloaded to your computer.
    5. Click Close.

11. Set the environment variable GOOGLE_APPLICATION_CREDENTIALS to the path of the JSON file that contains your service account key. This variable only applies to your current shell session, so if you open a new session, set the variable again.

    Example: Linux or macOS

    export GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"

    Replace KEY_PATH with the path of the JSON file that contains your service account key.

    For example:

    export GOOGLE_APPLICATION_CREDENTIALS="/home/user/Downloads/service-account-file.json"

    Example: Windows

    For PowerShell:

    $env:GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"

    Replace KEY_PATH with the path of the JSON file that contains your service account key.

    For example:

    $env:GOOGLE_APPLICATION_CREDENTIALS="C:\Users\username\Downloads\service-account-file.json"

    For command prompt:

    set GOOGLE_APPLICATION_CREDENTIALS=KEY_PATH

    Replace KEY_PATH with the path of the JSON file that contains your service account key.

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-rev20211107-1.32.1</version>
</dependency>
<dependency>
  <groupId>com.google.auth</groupId>
  <artifactId>google-auth-library-oauth2-http</artifactId>
  <version>1.4.0</version>
</dependency>
<dependency>
  <groupId>com.google.http-client</groupId>
  <artifactId>google-http-client-jackson2</artifactId>
  <version>1.41.8</version>
</dependency>
<dependency>
  <groupId>com.google.apis</groupId>
  <artifactId>google-api-services-iam</artifactId>
  <version>v1-rev20220509-1.32.1</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 Google Account, with the prefix user:. 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.

View on GitHub Feedback

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 member in the form "user:[e-mail]"
        var member = "your-member";
        // Role to be granted
        var role = "roles/logging.logWriter";

        // Initialize service
        CloudResourceManagerService crmService = InitializeService();

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

        // Get the project's policy and print all members 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 member 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 member 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 member 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.

View on GitHub Feedback

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 member in the form "user:[e-mail]"
	member := flag.String("member_id", "", "Your member 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 member the "Log writer" role for your project
	addBinding(crmService, *projectID, *member, role)

	// Gets the project's policy and prints all members 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 member 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 member 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 member 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 member 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 member
		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.

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import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.cloudresourcemanager.v3.CloudResourceManager;
import com.google.api.services.cloudresourcemanager.v3.model.Binding;
import com.google.api.services.cloudresourcemanager.v3.model.GetIamPolicyRequest;
import com.google.api.services.cloudresourcemanager.v3.model.Policy;
import com.google.api.services.cloudresourcemanager.v3.model.SetIamPolicyRequest;
import com.google.api.services.iam.v1.IamScopes;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.GoogleCredentials;
import java.io.IOException;
import java.security.GeneralSecurityException;
import java.util.Collections;
import java.util.List;

public class Quickstart {

  public static void main(String[] args) {
    // TODO: Replace with your project ID in the form "projects/your-project-id".
    String projectId = "your-project";
    // 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";

    // Initializes the Cloud Resource Manager service.
    CloudResourceManager crmService = null;
    try {
      crmService = initializeService();
    } catch (IOException | GeneralSecurityException e) {
      System.out.println("Unable to initialize service: \n" + e.getMessage() + e.getStackTrace());
    }

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

    // Get the project's policy and print all members with the "Log Writer" role
    Policy policy = getPolicy(crmService, projectId);
    Binding binding = null;
    List<Binding> bindings = policy.getBindings();
    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.getMembers()) {
      System.out.print("[" + m + "] ");
    }
    System.out.println();

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

  public static CloudResourceManager initializeService()
      throws IOException, GeneralSecurityException {
    // Use the Application Default Credentials strategy for authentication. For more info, see:
    // https://cloud.google.com/docs/authentication/production#finding_credentials_automatically
    GoogleCredentials credential =
        GoogleCredentials.getApplicationDefault()
            .createScoped(Collections.singleton(IamScopes.CLOUD_PLATFORM));

    // Creates the Cloud Resource Manager service object.
    CloudResourceManager service =
        new CloudResourceManager.Builder(
                GoogleNetHttpTransport.newTrustedTransport(),
                JacksonFactory.getDefaultInstance(),
                new HttpCredentialsAdapter(credential))
            .setApplicationName("iam-quickstart")
            .build();
    return service;
  }

  public static void addBinding(
      CloudResourceManager crmService, String projectId, String member, String role) {

    // Gets the project's policy.
    Policy policy = getPolicy(crmService, projectId);

    // Finds binding in policy, if it exists
    Binding binding = null;
    for (Binding b : policy.getBindings()) {
      if (b.getRole().equals(role)) {
        binding = b; 
        break;
      }
    }

    if (binding != null) {
      // If binding already exists, adds member to binding.
      binding.getMembers().add(member);
    } else {
      // If binding does not exist, adds binding to policy.
      binding = new Binding();
      binding.setRole(role);
      binding.setMembers(Collections.singletonList(member));
      policy.getBindings().add(binding);
    }

    // Sets the updated policy
    setPolicy(crmService, projectId, policy);
  }

  public static void removeMember(
      CloudResourceManager crmService, String projectId, String member, String role) {
    // Gets the project's policy.
    Policy policy = getPolicy(crmService, projectId);

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

    // Sets the updated policy.
    setPolicy(crmService, projectId, policy);
  }

  public static Policy getPolicy(CloudResourceManager crmService, String projectId) {
    // Gets the project's policy by calling the
    // Cloud Resource Manager Projects API.
    Policy policy = null;
    try {
      GetIamPolicyRequest request = new GetIamPolicyRequest();
      policy = crmService.projects().getIamPolicy(projectId, request).execute();
    } catch (IOException e) {
      System.out.println("Unable to get policy: \n" + e.getMessage() + e.getStackTrace());
    }
    return policy;
  }

  private static void setPolicy(CloudResourceManager crmService, String projectId, Policy policy) {
    // Sets the project's policy by calling the
    // Cloud Resource Manager Projects API.
    try {
      SetIamPolicyRequest request = new SetIamPolicyRequest();
      request.setPolicy(policy);
      crmService.projects().setIamPolicy(projectId, request).execute();
    } catch (IOException e) {
      System.out.println("Unable to set policy: \n" + e.getMessage() + e.getStackTrace());
    }
  }
}

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.

View on GitHub Feedback

import google.auth
import googleapiclient.discovery


def quickstart(project_id, member):
    """Gets a policy, adds a member, prints their permissions, and removes the member."""

    # Role to be granted.
    role = "roles/logging.logWriter"

    # Initializes service.
    crm_service = initialize_service()

    # 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 initialize_service():
    """Initializes a Cloud Resource Manager service."""

    credentials, _ = google.auth.default(
        scopes=["https://www.googleapis.com/auth/cloud-platform"]
    )
    crm_service = googleapiclient.discovery.build(
        "cloudresourcemanager", "v1", credentials=credentials
    )
    return crm_service


def modify_policy_add_role(crm_service, project_id, role, member):
    """Adds a new role binding to a policy."""

    policy = get_policy(crm_service, project_id)

    binding = None
    for b in policy["bindings"]:
        if b["role"] == role:
            binding = b
            break
    if binding is not None:
        binding["members"].append(member)
    else:
        binding = {"role": role, "members": [member]}
        policy["bindings"].append(binding)

    set_policy(crm_service, project_id, policy)


def modify_policy_remove_member(crm_service, project_id, role, member):
    """Removes a  member from a role binding."""

    policy = get_policy(crm_service, project_id)

    binding = next(b for b in policy["bindings"] if b["role"] == role)
    if "members" in binding and member in binding["members"]:
        binding["members"].remove(member)

    set_policy(crm_service, project_id, policy)


def get_policy(crm_service, project_id, version=3):
    """Gets IAM policy for a project."""

    policy = (
        crm_service.projects()
        .getIamPolicy(
            resource=project_id,
            body={"options": {"requestedPolicyVersion": version}},
        )
        .execute()
    )
    return policy


def set_policy(crm_service, project_id, policy):
    """Sets IAM policy for a project."""

    policy = (
        crm_service.projects()
        .setIamPolicy(resource=project_id, body={"policy": policy})
        .execute()
    )
    return 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

• Use the Cloud console to delete your project if you do not need it.

What's next

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