Update a policy

Demonstrates updating a policy.

Explore further

For detailed documentation that includes this code sample, see the following:

• Manage access to projects, folders, and organizations

Code sample

C++

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

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

namespace iam = ::google::cloud::iam_admin_v1;
[](std::string const& name) {
  iam::IAMClient client(iam::MakeIAMConnection());
  auto response =
      client.SetIamPolicy(name, [](google::iam::v1::Policy policy) {
        // change the policy, e.g., add/remove/edit a binding
        return policy;
      });
  if (!response) throw std::move(response).status();
  std::cout << "Policy successfully set: " << response->DebugString() << "\n";
}

C#

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

To authenticate to IAM, 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;

public partial class AccessManager
{
    public static Policy SetPolicy(string projectId, Policy policy)
    {
        var credential = GoogleCredential.GetApplicationDefault()
            .CreateScoped(CloudResourceManagerService.Scope.CloudPlatform);
        var service = new CloudResourceManagerService(
            new CloudResourceManagerService.Initializer
            {
                HttpClientInitializer = credential
            });

        return service.Projects.SetIamPolicy(new SetIamPolicyRequest
        {
            Policy = policy
        }, projectId).Execute();
    }
}

Java

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

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

import com.google.cloud.resourcemanager.v3.ProjectsClient;
import com.google.iam.admin.v1.ProjectName;
import com.google.iam.v1.Policy;
import com.google.iam.v1.SetIamPolicyRequest;
import com.google.protobuf.FieldMask;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;

public class SetProjectPolicy {
  public static void main(String[] args) throws IOException {
    // TODO(developer): Replace the variables before running the sample.
    // TODO: Replace with your project ID.
    String projectId = "your-project-id";
    // TODO: Replace with your policy, GetPolicy.getPolicy(projectId, serviceAccount).
    Policy policy = Policy.newBuilder().build();

    setProjectPolicy(policy, projectId);
  }

  // Sets a project's policy.
  public static Policy setProjectPolicy(Policy policy, String projectId)
          throws IOException {

    // 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 (ProjectsClient projectsClient = ProjectsClient.create()) {
      List<String> paths = Arrays.asList("bindings", "etag");
      SetIamPolicyRequest request = SetIamPolicyRequest.newBuilder()
              .setResource(ProjectName.of(projectId).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();

      return projectsClient.setIamPolicy(request);
    }
  }
}

Python

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

To authenticate to IAM, 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 set_project_policy(
    project_id: str, policy: policy_pb2.Policy, merge: bool = True
) -> policy_pb2.Policy:
    """
    Set policy for project. Pay attention that previous state will be completely rewritten.
    If you want to update only part of the policy follow the approach read->modify->write.
    For more details about policies check out https://cloud.google.com/iam/docs/policies

    project_id: ID or number of the Google Cloud project you want to use.
    policy: Policy which has to be set.
    merge: The strategy to be used forming the request. CopyFrom is clearing both mutable and immutable fields,
    when MergeFrom is replacing only immutable fields and extending mutable.
    https://googleapis.dev/python/protobuf/latest/google/protobuf/message.html#google.protobuf.message.Message.CopyFrom
    """
    client = resourcemanager_v3.ProjectsClient()

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

    # Etag should as fresh as possible to lower chance of collisions
    policy.ClearField("etag")
    if merge:
        current_policy.MergeFrom(policy)
    else:
        current_policy.CopyFrom(policy)

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

    # request.etag field also will be merged which means you are secured from collision,
    # but it means that request may fail and you need to leverage exponential retries approach
    # to be sure policy has been updated.
    request.policy.CopyFrom(current_policy)

    policy = client.set_iam_policy(request)
    return policy

What's next

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