Create and manage access control lists (ACLs)

Overview

This page describes how to control access to buckets and objects using Access Control Lists (ACLs). ACLs are a mechanism you can use to define who has access to your buckets and objects, as well as what level of access they have.

See the ACL overview to learn more about whether you should use ACLs for controlling access to your resources.

Required roles

To get the permissions that you need to create and manage ACLs, ask your administrator to grant you the Storage Admin (roles/storage.admin) IAM role on the bucket that contains the objects for which you want to create and manage ACLs.

This predefined role contains the permissions required to create and manage ACLs. To see the exact permissions that are required, expand the Required permissions section:

Required permissions

storage.buckets.get
storage.buckets.list

This permission is only required for using the Google Cloud console to perform the tasks on this page.

storage.buckets.setIamPolicy
storage.buckets.update
storage.objects.get
storage.objects.getIamPolicy
storage.objects.setIamPolicy
storage.objects.update

You can also get these permissions with custom roles.

For information about granting roles on buckets, see Use IAM with buckets.

Set or modify ACLs

Console

Go to the Cloud Storage browser in the Google Cloud console.
Go to the Cloud Storage browser
From the list of buckets, click the name of the bucket that contains the object whose ACL you want to modify.
Click the name of the object for which you want to set or modify ACLs.
Click Edit access.

A permission dialog with the object's current ACL opens.
Click + Add entry.
Choose the type of Entity to give permission to.

Entity specifies the type of thing that's getting the permission (for example a user or a group). Refer to Access Control Scopes for a list of supported values for Entity.
Enter a value in Name.

Name identifies a specific user, group, or other entity type. Refer to Access Control Scopes for a list of supported values for Name.

Together, Entity and Name define who the permission applies to.
Choose a value in Access.

Access defines the permission that you want to set on the object. Refer to Access Control Permissions for a list of supported values for Access.
Click Save.

To learn how to get detailed error information about failed Cloud Storage operations in the Google Cloud console, see Troubleshooting.

Command line

To add, modify, or remove an individual grant on an object, use the objects update command with the relevant flag:

gcloud storage objects update gs://BUCKET_NAME/OBJECT_NAME FLAG

Where:

BUCKET_NAME is the name of the bucket that contains the object that the modification applies to. For example, example-travel-maps.
OBJECT_NAME is the name of the object that the modification applies to. For example, paris.jpg.
FLAG is one of the following:
- --add-acl-grant, along with the grant you want to add or modify. For example, [email protected],role=READER.
- --remove-acl-grant, along with the entity whose access you want to remove. For example, [email protected].

To replace all ACLs for an object:

Define the ACLs in a JSON- or YAML-formatted file.
Use the objects update command with the --acl-file flag:
```
gcloud storage objects update gs://BUCKET_NAME/OBJECT_NAME --acl-file=FILE_LOCATION
```
Where:
- BUCKET_NAME is the name of the bucket that contains the object that the ACLs apply to. For example, example-travel-maps.
- OBJECT_NAME is the name of the object that the ACLs apply to. For example, paris.jpg.
- FILE_LOCATION is the local path to the file that contains the ACLs you've defined. For example, Desktop/acls.json.

The contents of an example ACLs file are shown below. These ACLs grant the owners of project 867489160491 along with the user [email protected] OWNER permission for the object paris.jpg, and they grant the members of the gs-announce group READER permission for this object:

[
  {
    "entity": "project-owners-867489160491",
    "role": "OWNER",
    "projectTeam": {
      "projectNumber": "867489160491",
      "team": "owners"
    },
  },
  {
    "entity": "[email protected]",
    "email": "[email protected]",
    "role": "OWNER"
  },
  {
    "entity": "[email protected]",
    "email": "[email protected]",
    "role": "READER"
  }
]

Client libraries

C++

For more information, see the Cloud Storage C++ API reference documentation.

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

The following sample adds an ACL to an object:

namespace gcs = ::google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& object_name, std::string const& entity) {
  StatusOr<gcs::ObjectAccessControl> patched_acl =
      client.CreateObjectAcl(bucket_name, object_name, entity,
                             gcs::ObjectAccessControl::ROLE_OWNER());

  if (!patched_acl) throw std::move(patched_acl).status();
  std::cout << "ACL entry for " << patched_acl->entity() << " in object "
            << patched_acl->object() << " in bucket " << patched_acl->bucket()
            << " is now " << *patched_acl << "\n";
}

The following sample removes an ACL from an object:

namespace gcs = ::google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& object_name, std::string const& entity) {
  StatusOr<gcs::ObjectMetadata> original_metadata = client.GetObjectMetadata(
      bucket_name, object_name, gcs::Projection::Full());
  if (!original_metadata) throw std::move(original_metadata).status();

  std::vector<gcs::ObjectAccessControl> original_acl =
      original_metadata->acl();
  auto it = std::find_if(original_acl.begin(), original_acl.end(),
                         [entity](gcs::ObjectAccessControl const& entry) {
                           return entry.entity() == entity &&
                                  entry.role() ==
                                      gcs::ObjectAccessControl::ROLE_OWNER();
                         });

  if (it == original_acl.end()) {
    std::cout << "Could not find entity " << entity << " for file "
              << object_name << " with role OWNER in bucket " << bucket_name
              << "\n";
    return;
  }

  gcs::ObjectAccessControl owner = *it;
  google::cloud::Status status =
      client.DeleteObjectAcl(bucket_name, object_name, owner.entity());

  if (!status.ok()) throw std::runtime_error(status.message());
  std::cout << "Deleted ACL entry for " << owner.entity() << " for file "
            << object_name << " in bucket " << bucket_name << "\n";
}

C#

For more information, see the Cloud Storage C# API reference documentation.

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

The following sample adds an ACL to an object:


using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;

public class AddFileOwnerSample
{
    public Google.Apis.Storage.v1.Data.Object AddFileOwner(
        string bucketName = "your-unique-bucket-name",
        string objectName = "my-file-name",
        string userEmail = "[email protected]")
    {
        var storage = StorageClient.Create();
        var storageObject = storage.GetObject(bucketName, objectName, new GetObjectOptions
        {
            Projection = Projection.Full
        });

        storageObject.Acl.Add(new ObjectAccessControl
        {
            Bucket = bucketName,
            Entity = $"user-{userEmail}",
            Role = "OWNER",
        });
        var updatedObject = storage.UpdateObject(storageObject);
        Console.WriteLine($"Added user { userEmail} as an owner on file { objectName}.");
        return updatedObject;
    }
}

The following sample removes an ACL from an object:


using Google.Cloud.Storage.V1;
using System;
using System.Linq;

public class RemoveFileOwnerSample
{
    public void RemoveFileOwner(
        string bucketName = "your-unique-bucket-name",
        string objectName = "your-object-name",
        string userEmail = "[email protected]")
    {
        var storage = StorageClient.Create();
        var storageObject = storage.GetObject(bucketName, objectName, new GetObjectOptions { Projection = Projection.Full });
        if (storageObject.Acl == null)
        {
            Console.WriteLine("No owner to remove");
        }
        else
        {
            storageObject.Acl = storageObject.Acl.Where((acl) => !(acl.Entity == $"user-{userEmail}" && acl.Role == "OWNER")).ToList();
            var updatedObject = storage.UpdateObject(storageObject);
            Console.WriteLine($"Removed user {userEmail} from file {objectName}.");
        }
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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

The following sample adds an ACL to an object:

import (
	"context"
	"fmt"

	"cloud.google.com/go/storage"
)

// addFileOwner adds ACL to the specified object.
func addFileOwner(bucket, object string, entity storage.ACLEntity) error {
	// bucket := "bucket-name"
	// object := "object-name"
	// entity := storage.AllUsers
	role := storage.RoleOwner

	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %w", err)
	}
	defer client.Close()

	acl := client.Bucket(bucket).Object(object).ACL()
	if err := acl.Set(ctx, entity, role); err != nil {
		return fmt.Errorf("ACLHandle.Set: %w", err)
	}
	return nil
}

The following sample removes an ACL from an object:

import (
	"context"
	"fmt"

	"cloud.google.com/go/storage"
)

// removeFileOwner removes default ACL from the given object.
func removeFileOwner(bucket, object string, entity storage.ACLEntity) error {
	// bucket := "bucket-name"
	// object := "object-name"
	// entity := storage.AllUsers
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %w", err)
	}
	defer client.Close()

	acl := client.Bucket(bucket).Object(object).ACL()
	if err := acl.Delete(ctx, entity); err != nil {
		return fmt.Errorf("ACLHandle.Delete: %w", err)
	}
	return nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

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

The following sample adds an ACL to an object:


import com.google.cloud.storage.Acl;
import com.google.cloud.storage.Acl.Role;
import com.google.cloud.storage.Acl.User;
import com.google.cloud.storage.Blob;
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;

public class AddFileOwner {

  public static void addFileOwner(
      String projectId, String bucketName, String userEmail, String blobName) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // Email of the user you wish to add as a file owner
    // String userEmail = "[email protected]"

    // The name of the blob/file that you wish to modify permissions on
    // String blobName = "your-blob-name";

    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();
    Blob blob = storage.get(BlobId.of(bucketName, blobName));
    Acl newOwner = Acl.of(new User(userEmail), Role.OWNER);

    blob.createAcl(newOwner);
    System.out.println(
        "Added user "
            + userEmail
            + " as an owner on file "
            + blobName
            + " in bucket "
            + bucketName);
  }
}

The following sample removes an ACL from an object:


import com.google.cloud.storage.Acl.User;
import com.google.cloud.storage.Blob;
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;

public class RemoveFileOwner {

  public static void removeFileOwner(
      String projectId, String bucketName, String userEmail, String blobName) {
    // The ID of your GCP project
    // String projectId = "your-project-id";

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // Email of the user you wish to remove as a file owner
    // String userEmail = "[email protected]"

    // The name of the blob/file that you wish to modify permissions on
    // String blobName = "your-blob-name";

    Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();
    Blob blob = storage.get(BlobId.of(bucketName, blobName));
    User ownerToRemove = new User(userEmail);

    boolean success = blob.deleteAcl(ownerToRemove);
    if (success) {
      System.out.println(
          "Removed user "
              + userEmail
              + " as an owner on file "
              + blobName
              + " in bucket "
              + bucketName);
    } else {
      System.out.println("User " + userEmail + " was not found");
    }
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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

The following sample adds an ACL to an object:

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The name of the file to access
// const fileName = 'file.txt';

// The email address of the user to add
// const userEmail = 'user-email-to-add';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function addFileOwner() {
  await storage
    .bucket(bucketName)
    .file(fileName)
    .acl.owners.addUser(userEmail);

  console.log(`Added user ${userEmail} as an owner on file ${fileName}.`);
}

addFileOwner().catch(console.error);

The following sample removes an ACL from an object:

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The ID of your GCS file
// const fileName = 'your-file-name';

// The email address of the user to remove
// const userEmail = 'user-email-to-remove';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function removeFileOwner() {
  // Removes the user from the access control list of the file. You can use
  // deleteAllUsers(), deleteDomain(), deleteProject(), deleteGroup(), and
  // deleteAllAuthenticatedUsers() to remove access for different types of entities.
  await storage
    .bucket(bucketName)
    .file(fileName)
    .acl.owners.deleteUser(userEmail);

  console.log(`Removed user ${userEmail} from file ${fileName}.`);
}

removeFileOwner().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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

The following sample adds an ACL to an object:

use Google\Cloud\Storage\StorageClient;

/**
 * Add an entity and role to an object's ACL.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 *        (e.g. 'my-bucket')
 * @param string $objectName The name of your Cloud Storage object.
 *        (e.g. 'my-object')
 * @param string $entity The entity for which to update access controls.
 *        (e.g. '[email protected]')
 * @param string $role The permissions to add for the specified entity.
 *        (e.g. 'OWNER')
 */
function add_object_acl(string $bucketName, string $objectName, string $entity, string $role): void
{
    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $object = $bucket->object($objectName);
    $acl = $object->acl();
    $acl->add($entity, $role);
    printf('Added %s (%s) to gs://%s/%s ACL' . PHP_EOL, $entity, $role, $bucketName, $objectName);
}

The following sample removes an ACL from an object:

use Google\Cloud\Storage\StorageClient;

/**
 * Delete an entity from an object's ACL.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 *        (e.g. 'my-bucket')
 * @param string $objectName The name of your Cloud Storage object.
 *        (e.g. 'my-object')
 * @param string $entity The entity for which to update access controls.
 *        (e.g. '[email protected]')
 */
function delete_object_acl(string $bucketName, string $objectName, string $entity): void
{
    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $object = $bucket->object($objectName);
    $acl = $object->acl();
    $acl->delete($entity);
    printf('Deleted %s from gs://%s/%s ACL' . PHP_EOL, $entity, $bucketName, $objectName);
}

Python

For more information, see the Cloud Storage Python API reference documentation.

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

The following sample adds an ACL to an object:

from google.cloud import storage


def add_blob_owner(bucket_name, blob_name, user_email):
    """Adds a user as an owner on the given blob."""
    # bucket_name = "your-bucket-name"
    # blob_name = "your-object-name"
    # user_email = "[email protected]"

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)
    blob = bucket.blob(blob_name)

    # Reload fetches the current ACL from Cloud Storage.
    blob.acl.reload()

    # You can also use `group`, `domain`, `all_authenticated` and `all` to
    # grant access to different types of entities. You can also use
    # `grant_read` or `grant_write` to grant different roles.
    blob.acl.user(user_email).grant_owner()
    blob.acl.save()

    print(
        "Added user {} as an owner on blob {} in bucket {}.".format(
            user_email, blob_name, bucket_name
        )
    )

The following sample removes an ACL from an object:

from google.cloud import storage


def remove_blob_owner(bucket_name, blob_name, user_email):
    """Removes a user from the access control list of the given blob in the
    given bucket."""
    # bucket_name = "your-bucket-name"
    # blob_name = "your-object-name"
    # user_email = "[email protected]"

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)
    blob = bucket.blob(blob_name)

    # You can also use `group`, `domain`, `all_authenticated` and `all` to
    # remove access for different types of entities.
    blob.acl.user(user_email).revoke_read()
    blob.acl.user(user_email).revoke_write()
    blob.acl.user(user_email).revoke_owner()
    blob.acl.save()

    print(
        f"Removed user {user_email} from blob {blob_name} in bucket {bucket_name}."
    )

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

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

The following sample adds an ACL to an object:

# The ID of your GCS bucket
# bucket_name = "your-unique-bucket-name"
# file_name   = "Name of a file in the Storage bucket"
# email       = "Google Cloud Storage ACL Entity email"

require "google/cloud/storage"

storage = Google::Cloud::Storage.new
bucket  = storage.bucket bucket_name
file    = bucket.file file_name

file.acl.add_owner email

puts "Added OWNER permission for #{email} to #{file_name}"

The following sample removes an ACL from an object:

# The ID of your GCS bucket
# bucket_name = "your-unique-bucket-name"
# file_name   = "Name of a file in the Storage bucket"
# email       = "Google Cloud Storage ACL Entity email"

require "google/cloud/storage"

storage = Google::Cloud::Storage.new
bucket  = storage.bucket bucket_name
file    = bucket.file file_name

file.acl.delete email

puts "Removed ACL permissions for #{email} from #{file_name}"

REST APIs

JSON API

When creating an object, you can specify the acl[] property in the request body or the predefinedAcl query parameter in an insert request. For an existing object, specify the acl[] property or the predefinedAcl query parameter in a patch or update request.

For the definition of the object ACL property, see the ObjectAccessControls resource.

Define the ACLs in a JSON file.

For example, if the ACL grants the owners of project 867489160491 and the user [email protected] OWNER permission, along with granting the members of the gs-announce group READER permission, then you could have a file named acls.json with the following content:

{
"acl": [
  {
    "entity": "project-owners-867489160491",
    "role": "OWNER",
    "projectTeam": {
      "projectNumber": "867489160491",
      "team": "owners"
    }
  },
  {
    "entity": "[email protected]",
    "role": "OWNER",
    "email": "[email protected]"
  },
  {
    "entity": "[email protected]",
    "role": "READER",
    "email": "[email protected]"
  }
]
}

Send a patch request with the JSON file, and specify the object to set the ACLs on.

For example, the following cURL command applies a JSON payload from the document acls.json to an object named paris.jpg in the bucket example-travel-maps:

curl -X PATCH --data @acls.json -H "Content-Type: application/json" \
    -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    https://storage.googleapis.com/storage/v1/b/example-travel-maps/o/paris.jpg

XML API

In the XML API, you work with ACLs in XML format. You must attach an XML document to the body of requests to change bucket and object ACLs. An XML document is returned when you get bucket and object ACLs. The XML document contains the individual bucket or object ACL entries.

After creating a bucket with a PUT Bucket request, use a second PUT Bucket request with the ?acl parameter to change the bucket ACL.
After uploading an object with a PUT Object request, change the ACL with another PUT request using the ?acl parameter or the x-googl-acl request header.

For example, the following cURL command applies an XML payload from the document acls.xml to an object named paris.jpg in the bucket example-travel-maps:

curl -X PUT --data-binary @acls.xml \
    -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    https://storage.googleapis.com/example-travel-maps/paris.jpg?acl

Use the following ACL syntax for the XML document:

Element	Description
`AccessControlList`	Container for `Entries` and `Owner` elements.
`Owner`	Container for `DisplayName` and `ID` elements. This element is not required for objects since an object is always owned by the user who uploaded it. This element is used when you are using Amazon S3 ACL syntax in a migration scenario. Amazon Simple Storage Service^™ and Amazon S3^™ are trademarks of Amazon.com, Inc. or its affiliates in the United States and/or other countries.
`ID`	Google Cloud Storage ID of the bucket owner.
`DisplayName`	Not currently implemented. The value is always an empty string.
`Entries`	Container for zero or more `Entry` elements.
`Entry`	Container for `Scope` and `Permission` elements. An `Entry` must contain only one `Scope` and one `Permission` element.
`Scope`	Container for an `ID`, `EmailAddress`, or `Domain` element that defines the ACL scope. This element must have a `type` attribute that contains one of the following values: `UserByID`, `UserByEmail`, `GroupByID`, `GroupByEmail`, `GroupByDomain`, `AllUsers`, or `AllAuthenticatedUsers`.
`ID`	An identifier for the grantee when the permission entry is specified by ID.
`EmailAddress`	The email identifier for the grantee when the permission entry is specified by email.
`Domain`	The domain identifier for the grantee when the permission entry is specified by domain.
`Name`	Optional element that can be specified or that can be automatically added if the scope is `UserByEmail` or `GroupByEmail`.
`Permission`	The permission granted `READ`, `WRITE`, or `FULL_CONTROL`.

When working with ACLs using the XML API:

You can only use the XML format described above.
You cannot set duplicate scopes.

You can have many entries in your ACL XML, but you cannot have entries with duplicate scopes. For example, you cannot have two entries with the same scope element of [email protected].

The following example shows different bucket ACL entries:

<?xml version="1.0" encoding="UTF-8"?>
<AccessControlList>
  <Owner>
    <ID>00b4903a9721...</ID>
  </Owner>
  <Entries>
    <Entry>
      <Scope type="GroupById">
        <ID>00b4903a9722...</ID>
      </Scope>
      <Permission>FULL_CONTROL</Permission>
    </Entry>
    <Entry>
      <Scope type="GroupByDomain">
        <Domain>example.com</Domain>
      </Scope>
      <Permission>READ</Permission>
    </Entry>
    <Entry>
      <Scope type="GroupByEmail">
        <EmailAddress>[email protected]</EmailAddress>
      </Scope>
      <Permission>READ</Permission>
    </Entry>
    <Entry>
      <Scope type="UserByEmail">
        <EmailAddress>[email protected]</EmailAddress>
        <Name>jane</Name>
      </Scope>
      <Permission>READ</Permission>
    </Entry>
    <Entry>
      <Scope type="AllUsers"/>
      <Permission>READ</Permission>
    </Entry>
    <Entry>
      <Scope type="AllAuthenticatedUsers"/>
      <Permission>READ</Permission>
    </Entry>
  </Entries>
</AccessControlList>

Set the Name element in ACL XML

When you retrieve an ACL from a bucket or object, you might notice an additional <Name> element appended to some of your entries. For example, you might see an entry that looks like the following:

<Entry>
  <Scope type="UserByEmail">
    <EmailAddress>[email protected]</EmailAddress>
    <Name>Jane</Name>
  </Scope>
  <Permission>FULL_CONTROL</Permission>
</Entry>

These optional <Name> elements are populated in two circumstances:

When the bucket or object's ACLs include <Name> as an element.

When you set ACLs, you can choose to include the <Name> element with your ACL entries. You can provide any value in the <Name> element, and Cloud Storage remembers these values until the ACL is removed or replaced. This approach can be useful if you are using identifiers that aren't easily identifiable, like Google Cloud Storage IDs.
When a UserByEmail or GroupByEmail scope contains a public Google profile.

If you use either of these scopes but do not provide a <Name> element, Cloud Storage checks if the user or Google Group associated with the email address has a public Google profile with a public name. If so, Cloud Storage automatically populates the <Name> element with the public name.

Apply a predefined ACL

Rather than specifying the entire ACL one entry at a time as shown above, you can use a predefined ACL, which will automatically apply a number of entries customized to a specific scenario. You can apply a predefined ACL to either a bucket or an object by using the Google Cloud CLI, the JSON API, or the XML API.

On new objects

To apply a predefined ACL to an object during object upload:

Console

You cannot apply a predefined ACL using the Google Cloud console. Use gcloud storage instead.

Command line

Use the gcloud storage cp command with the --predefined-acl flag:

gcloud storage cp OBJECT gs://BUCKET_NAME --predefined-acl=PREDEFINED_ACL

For example, to apply the predefined ACL bucketOwnerRead while uploading an object paris.jpg to a bucket example-travel-maps:

gcloud storage cp paris.jpg gs://example-travel-maps --predefined-acl=bucketOwnerRead

REST APIs

JSON API

Use the predefinedAcl query string parameter in an insert request to apply the prefined ACL.

For example, to apply the predefined ACL bucketOwnerRead while uploading an object paris.jpg to a bucket example-travel-maps:

curl -X POST --data-binary @paris.jpg -H "Content-Type: image/jpeg" \
    -H "Authorization: Bearer $(gcloud auth print-access-token)"  \
    "https://storage.googleapis.com/upload/storage/v1/b/example-travel-maps/o?name=paris.jpg&predefinedAcl=bucketOwnerRead"

XML API

Use the x-goog-acl header in a Put Object request to apply the predefined ACL.

For example, to apply the predefined ACL bucket-owner-read while uploading an object paris.jpg to a bucket example-travel-maps:

curl -X PUT --upload-file paris.jpg -H "x-goog-acl: bucket-owner-read" \
    -H "Authorization: Bearer $(gcloud auth print-access-token)"  \
    https://storage.googleapis.com/example-travel-maps/paris.jpg

On existing buckets or objects

You can also apply a predefined ACL to an existing bucket or object, which is useful if you want to change from one predefined ACL to another, or you want to update custom ACLs to a predefined ACL.

Console

You cannot apply a predefined ACL using the Google Cloud console. Use gcloud storage instead.

Command line

Use the objects update command with the --predefined-acl flag:

gcloud storage objects update gs://BUCKET_NAME/OBJECT_NAME --predefined-acl=PREDEFINED_ACL_NAME

For example, to apply the predefined ACL private to the object paris.jpg in the bucket example-travel-maps:

gcloud storage objects update gs://example-travel-maps/paris.jpg --predefined-acl=private

REST APIs

JSON API

Use the predefinedAcl query string parameter, and specify an empty acl property in a patch request to apply the prefined ACL.

For example, to apply the predefined ACL private to the object paris.jpg in the bucket example-travel-maps:

curl -X PATCH --data '{"acl": []}'  -H "Content-Type: application/json" \
    -H "Authorization: Bearer $(gcloud auth print-access-token)"  \
    https://storage.googleapis.com/storage/v1/b/example-travel-maps/o/paris.jpg?predefinedAcl=private

XML API

Use the x-goog-acl header with the acl query string parameter in a Put Object request, but don't include an XML document in your request.

For example, to apply the predefined ACL private to the object paris.jpg in the bucket example-travel-maps:

curl -X PUT -H "Content-Length: 0" \
    -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    -H "x-goog-acl: private" \
    https://storage.googleapis.com/example-travel-maps/paris.jpg?acl

Set default object ACLs

To avoid setting ACLs every time you create a new object, you can set a default object ACL on a bucket. After you do this, every new object that is added to that bucket that does not explicitly have an ACL applied to it will have the default applied to it. For example, you might want to specify that only a certain group of users have access to most objects in a particular bucket. You can change the default object ACL, and then add objects to the bucket. These added objects have the default object ACL you specified automatically applied to them; however, you can give specific objects different ACLs, in which case those objects do not have the default ACL applied to them.

To view and change the default object ACL for a bucket:

Console

You cannot set default object ACLs using the Google Cloud console. Use gcloud storage instead.

Command line

Use the buckets describe command with the --format flag to retrieve the default object ACL for the bucket:
```
gcloud storage buckets describe gs://BUCKET_NAME --format="default(default_acl)"
```
Where BUCKET_NAME is the name of the bucket whose default object ACL you want to view. For example, my-bucket.
Use the buckets update command with the desired flag to modify the default object ACL for the bucket:
```
gcloud storage buckets update gs://BUCKET_NAME FLAG
```
Where:
- BUCKET_NAME is the name of the bucket whose default object ACL you want to modify. For example, my-bucket.
- FLAG is one of the following:
  - --add-default-object-acl-grant and a grant that you want to add to the overall default object ACL for the bucket.
  - --default-object-acl-file and the path to a local file that defines a new default object ACL for the bucket.
  - --predefined-default-object-acl and the name of a predefined object ACL that you want to replace the existing default object ACL for the bucket with.
  - --remove-default-object-acl-grant and an entity that you want to remove from the overall default object ACL for the bucket.

Client libraries

C++

For more information, see the Cloud Storage C++ API reference documentation.

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

The following sample adds a default object ACL to a bucket:

namespace gcs = ::google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& entity, std::string const& role) {
  StatusOr<gcs::ObjectAccessControl> default_object_acl =
      client.CreateDefaultObjectAcl(bucket_name, entity, role);
  if (!default_object_acl) throw std::move(default_object_acl).status();

  std::cout << "Role " << default_object_acl->role()
            << " will be granted default to " << default_object_acl->entity()
            << " on any new object created on bucket "
            << default_object_acl->bucket() << "\n"
            << "Full attributes: " << *default_object_acl << "\n";
}

The following sample deletes a default object ACL from a bucket:

namespace gcs = ::google::cloud::storage;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& entity) {
  google::cloud::Status status =
      client.DeleteDefaultObjectAcl(bucket_name, entity);

  if (!status.ok()) throw std::runtime_error(status.message());
  std::cout << "Deleted ACL entry for " << entity << " in bucket "
            << bucket_name << "\n";
}

C#

For more information, see the Cloud Storage C# API reference documentation.

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

The following sample prints the default object ACL for a bucket:


using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;
using System.Collections.Generic;

public class PrintBucketDefaultAclSample
{
    public IEnumerable<ObjectAccessControl> PrintBucketDefaultAcl(string bucketName = "your-unique-bucket-name")
    {
        var storage = StorageClient.Create();
        var bucket = storage.GetBucket(bucketName, new GetBucketOptions { Projection = Projection.Full });

        foreach (var acl in bucket.DefaultObjectAcl)
        {
            Console.WriteLine($"{acl.Role}:{acl.Entity}");
        }

        return bucket.DefaultObjectAcl;
    }
}

The following sample adds a default object ACL to a bucket:


using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;

public class AddBucketDefaultOwnerSample
{
    public Bucket AddBucketDefaultOwner(
        string bucketName = "your-unique-bucket-name",
        string userEmail = "[email protected]")
    {
        var storage = StorageClient.Create();
        var bucket = storage.GetBucket(bucketName, new GetBucketOptions { Projection = Projection.Full });

        bucket.DefaultObjectAcl.Add(new ObjectAccessControl
        {
            Bucket = bucketName,
            Entity = $"user-{userEmail}",
            Role = "OWNER",
        });
        var updatedBucket = storage.UpdateBucket(bucket);
        Console.WriteLine($"Added user {userEmail} as a default owner on bucket {bucketName}.");
        return updatedBucket;
    }
}

The following sample deletes a default object ACL from a bucket:


using Google.Cloud.Storage.V1;
using System;
using System.Linq;

public class RemoveBucketDefaultOwnerSample
{
    public void RemoveBucketDefaultOwner(
        string bucketName = "your-unique-bucket-name",
        string userEmail = "[email protected]")
    {
        var storage = StorageClient.Create();
        var bucket = storage.GetBucket(bucketName, new GetBucketOptions { Projection = Projection.Full });
        if (bucket.DefaultObjectAcl == null)
        {
            Console.WriteLine("No default owner to remove");
        }
        else
        {
            bucket.DefaultObjectAcl = bucket.DefaultObjectAcl.Where(acl => !(acl.Entity == $"user-{userEmail}" && acl.Role == "OWNER")).ToList();
            var updatedBucket = storage.UpdateBucket(bucket);
            Console.WriteLine($"Removed user {userEmail} from bucket {bucketName}.");
        }
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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

The following sample adds a default object ACL to a bucket:

import (
	"context"
	"fmt"

	"cloud.google.com/go/storage"
)

// addBucketDefaultOwner adds default ACL to the specified bucket.
func addBucketDefaultOwner(bucket string, entity storage.ACLEntity) error {
	// bucket := "bucket-name"
	// entity := storage.AllUsers
	role := storage.RoleOwner

	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %w", err)
	}
	defer client.Close()

	acl := client.Bucket(bucket).DefaultObjectACL()
	if err := acl.Set(ctx, entity, role); err != nil {
		return fmt.Errorf("ACLHandle.Set: %w", err)
	}
	return nil
}

The following sample deletes a default object ACL from a bucket:

import (
	"context"
	"fmt"

	"cloud.google.com/go/storage"
)

// deleteDefaultBucketACL removes default ACL from a bucket.
func removeBucketDefaultOwner(bucket string, entity storage.ACLEntity) error {
	// bucket := "bucket-name"
	// entity := storage.AllUsers
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %w", err)
	}
	defer client.Close()

	acl := client.Bucket(bucket).DefaultObjectACL()
	if err := acl.Delete(ctx, entity); err != nil {
		return fmt.Errorf("ACLHandle.Delete: %w", err)
	}
	return nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

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

The following sample adds a default object ACL to a bucket:


import com.google.cloud.storage.Acl;
import com.google.cloud.storage.Acl.Role;
import com.google.cloud.storage.Acl.User;
import com.google.cloud.storage.Bucket;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;

public class AddBucketDefaultOwner {

  public static void addBucketDefaultOwner(String bucketName, String userEmail) {

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // The email of the user you wish to add as a default owner
    // String userEmail = "[email protected]"

    Storage storage = StorageOptions.newBuilder().build().getService();
    Bucket bucket = storage.get(bucketName);
    Acl newDefaultOwner = Acl.of(new User(userEmail), Role.OWNER);

    bucket.createDefaultAcl(newDefaultOwner);
    System.out.println("Added user " + userEmail + " as an owner on " + bucketName);
  }
}

The following sample deletes a default object ACL from a bucket:


import com.google.cloud.storage.Acl.User;
import com.google.cloud.storage.Bucket;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;

public class RemoveBucketDefaultOwner {

  public static void removeBucketDefaultOwner(String bucketName, String userEmail) {

    // The ID of your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // The email of the user you wish to remove as a default owner
    // String userEmail = "[email protected]"

    Storage storage = StorageOptions.newBuilder().build().getService();
    Bucket bucket = storage.get(bucketName);
    User userToRemove = new User(userEmail);

    boolean success = bucket.deleteDefaultAcl(userToRemove);
    if (success) {
      System.out.println("Removed user " + userEmail + " as an owner on " + bucketName);
    } else {
      System.out.println("User " + userEmail + " was not found");
    }
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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

The following sample adds a default object ACL to a bucket:

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The email address of the user to add
// const userEmail = 'user-email-to-add';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function addBucketDefaultOwner() {
  // Makes the user an owner in the default ACL of the bucket. You can use
  // addAllUsers(), addDomain(), addProject(), addGroup(), and
  // addAllAuthenticatedUsers() to grant access to different types of entities.
  // You can also use "readers" and "writers" to grant different roles.
  await storage.bucket(bucketName).acl.default.owners.addUser(userEmail);

  console.log(`Added user ${userEmail} as an owner on bucket ${bucketName}.`);
}

addBucketDefaultOwner().catch(console.error);

The following sample deletes a default object ACL from a bucket:

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The email address of the user to remove
// const userEmail = 'user-email-to-remove';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function removeBucketDefaultOwner() {
  // Removes the user from the access control list of the bucket. You can use
  // deleteAllUsers(), deleteDomain(), deleteProject(), deleteGroup(), and
  // deleteAllAuthenticatedUsers() to remove access for different types of entities.
  await storage.bucket(bucketName).acl.default.owners.deleteUser(userEmail);

  console.log(`Removed user ${userEmail} from bucket ${bucketName}.`);
}

removeBucketDefaultOwner().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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

The following sample adds a default object ACL to a bucket:

use Google\Cloud\Storage\StorageClient;

/**
 * Add an entity and role to a bucket's default ACL.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 *        (e.g. 'my-bucket')
 * @param string $entity The entity for which to update access controls.
 *        (e.g. '[email protected]')
 * @param string $role The permissions to add for the specified entity.
 *        (e.g. 'OWNER')
 */
function add_bucket_default_acl(string $bucketName, string $entity, string $role): void
{
    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $acl = $bucket->defaultAcl();
    $acl->add($entity, $role);
    printf('Added %s (%s) to gs://%s default ACL' . PHP_EOL, $entity, $role, $bucketName);
}

The following sample deletes a default object ACL from a bucket:

use Google\Cloud\Storage\StorageClient;

/**
 * Delete an entity from a bucket's default ACL.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 *        (e.g. 'my-bucket')
 * @param string $entity The entity for which to update access controls.
 *        (e.g. '[email protected]')
 */
function delete_bucket_default_acl(string $bucketName, string $entity): void
{
    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $acl = $bucket->defaultAcl();
    $acl->delete($entity);
    printf('Deleted %s from gs://%s default ACL' . PHP_EOL, $entity, $bucketName);
}

Python

For more information, see the Cloud Storage Python API reference documentation.

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

The following sample adds a default object ACL to a bucket:

from google.cloud import storage


def add_bucket_default_owner(bucket_name, user_email):
    """Adds a user as an owner in the given bucket's default object access
    control list."""
    # bucket_name = "your-bucket-name"
    # user_email = "[email protected]"

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)

    # Reload fetches the current ACL from Cloud Storage.
    bucket.acl.reload()

    # You can also use `group`, `domain`, `all_authenticated` and `all` to
    # grant access to different types of entities. You can also use
    # `grant_read` or `grant_write` to grant different roles.
    bucket.default_object_acl.user(user_email).grant_owner()
    bucket.default_object_acl.save()

    print(
        "Added user {} as an owner in the default acl on bucket {}.".format(
            user_email, bucket_name
        )
    )

The following sample deletes a default object ACL from a bucket:

from google.cloud import storage


def remove_bucket_default_owner(bucket_name, user_email):
    """Removes a user from the access control list of the given bucket's
    default object access control list."""
    # bucket_name = "your-bucket-name"
    # user_email = "[email protected]"

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)

    # Reload fetches the current ACL from Cloud Storage.
    bucket.acl.reload()

    # You can also use `group`, `domain`, `all_authenticated` and `all` to
    # remove access for different types of entities.
    bucket.default_object_acl.user(user_email).revoke_read()
    bucket.default_object_acl.user(user_email).revoke_write()
    bucket.default_object_acl.user(user_email).revoke_owner()
    bucket.default_object_acl.save()

    print(
        f"Removed user {user_email} from the default acl of bucket {bucket_name}."
    )

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

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

The following sample adds a default object ACL to a bucket:

# The ID of your GCS bucket
# bucket_name = "your-unique-bucket-name"
# email       = "Google Cloud Storage ACL Entity email"

require "google/cloud/storage"

storage = Google::Cloud::Storage.new
bucket  = storage.bucket bucket_name

bucket.default_acl.add_owner email

puts "Added default OWNER permission for #{email} to #{bucket_name}"

The following sample deletes a default object ACL from a bucket:

# The ID of your GCS bucket
# bucket_name = "your-unique-bucket-name"
# email       = "Google Cloud Storage ACL Entity email"

require "google/cloud/storage"

storage = Google::Cloud::Storage.new
bucket  = storage.bucket bucket_name

bucket.default_acl.delete email

puts "Removed default ACL permissions for #{email} from #{bucket_name}"

REST APIs

JSON API

Retrieve the default object ACL with a GET request. For example:

curl -X GET -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    https://storage.googleapis.com/storage/v1/b/BUCKET_NAME?projection=full

Use a patch request to replace the default object ACL. For example, the following request replaces the default object ACL with the ACL specified in defacls.json for a bucket example-travel-maps:

curl -X PATCH --data @defacls.json -H "Content-Type: application/json" -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    https://storage.googleapis.com/storage/v1/b/example-travel-maps

An example of defacls.json:

{
"defaultObjectAcl": [
  {
    "email": "[email protected]",
    "entity": "[email protected]",
    "role": "READER"
  }
]
}

XML API

Retrieve the default object ACL with a GET request scoped to your bucket and the ?defaultObjectAcl parameter. For example:

curl -X GET -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    https://storage.googleapis.com/BUCKET_NAME?defaultObjectAcl

Use a PUT request scoped to your bucket with the ?defaultObjectAcl parameter to replace the default object ACL with the ACL specified in acls.xml. For example:

curl -X PUT --data-binary @acls.xml -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    http://storage.googleapis.com/BUCKET_NAME?defaultObjectAcl

An example of acls.xml:

<AccessControlList>
  <Entries>
    <Entry>
      <Permission>FULL_CONTROL</Permission>
      <Scope type="GroupByEmail">
        <EmailAddress>[email protected]</EmailAddress>
      </Scope>
    </Entry>
  </Entries>
</AccessControlList>

The syntax of ACLs is discussed in Setting ACLs. You can also specify a predefined ACL as the default object ACL.

To set the default object ACL for a bucket to a predefined ACL:

Console

You cannot set default object ACLs using the Google Cloud console. Use gcloud storage instead.

Command line

Use the buckets update command with the --predefined-default-object-acl flag:

gcloud storage buckets update gs://BUCKET_NAME --predefined-default-object-acl=PREDEFINED_ACL

Where:

BUCKET_NAME is the name of the bucket whose default object ACL you want to modify. For example, my-bucket.
PREDEFINED_ACL is the name of a valid predefined ACL. For example, projectPrivate.

REST APIs

JSON API

Use a PUT request and the predefinedAcl parameter.

For example:

curl -X PUT -H "Content-Length: 0" -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    https://storage.googleapis.com/storage/v1/b/BUCKET_NAME?predefinedAcl=private

XML API

Use a PUT request scoped to your bucket with the ?defaultObjectAcl parameter and the x-goog-acl header.

For example:

curl -X PUT -H "x-goog-acl: project-private" -H "Content-Length: 0" -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    http://storage.googleapis.com/BUCKET_NAME?defaultObjectAcl

Default object ACLs for newly created buckets:

The following examples show the default object ACLs that automatically apply to newly created buckets when you don't specify your own default object ACLs as part of the request. To see if your bucket's default object ACLs have been changed, compare your bucket's current default object ACLs to the examples below.

Console

You cannot work with default object ACLs using the Google Cloud console. Use gcloud storage instead.

Command line

In the example below, the project ID is "123412341234"; your project ID will be different.

defaultObjectAcl:
– entity: project-owners-123412341234
  etag: CAE=
  kind: storage#objectAccessControl
  projectTeam:
    projectNumber: '123412341234'
    team: owners
  role: OWNER
– entity: project-editors-123412341234
  etag: CAE=
  kind: storage#objectAccessControl
  projectTeam:
    projectNumber: '123412341234'
    team: editors
  role: OWNER
– entity: project-viewers-123412341234
  etag: CAE=
  kind: storage#objectAccessControl
  projectTeam:
    projectNumber: '123412341234'
    team: viewers
  role: READER

REST APIs

JSON API

In the example below, the project ID is "123412341234"; your project ID will be different.

"defaultObjectAcl": [
  {
    "kind": "storage#objectAccessControl",
    "entity": "project-owners-123412341234",
    "role": "OWNER",
    "projectTeam": {
      "projectNumber": "123412341234",
      "team": "owners"
    }
  },
  {
    "kind": "storage#objectAccessControl",
    "entity": "project-editors-123412341234",
    "role": "OWNER",
    "projectTeam": {
      "projectNumber": "123412341234",
      "team": "editors"
    }
  },
  {
    "kind": "storage#objectAccessControl",
    "entity": "project-viewers-123412341234",
    "role": "READER",
    "projectTeam": {
      "projectNumber": "123412341234",
      "team": "viewers"
    }
  }
]

XML API

In the example below, the project role IDs start with "00b4903a97..."; your project IDs will be different.

<?xml version='1.0' encoding='UTF-8'?>
<AccessControlList>
  <Entries>
    <Entry>
      <Scope type='GroupById'>
        <ID>00b4903a9721...</ID>
      </Scope>
      <Permission>FULL_CONTROL</Permission>
    </Entry>
    <Entry>
      <Scope type='GroupById'>
        <ID>00b4903a9722...</ID>
      </Scope>
      <Permission>FULL_CONTROL</Permission>
    </Entry>
    <Entry>
      <Scope type='GroupById'>
        <ID>00b4903a9723...</ID>
      </Scope>
      <Permission>READ</Permission>
    </Entry>
  </Entries>
</AccessControlList>

Note that the default object ACL for a newly created bucket is equivalent to the predefined projectPrivate ACL.

Retrieving ACLs

To get the ACL of an existing resource:

Console

Go to the Cloud Storage browser in the Google Cloud console.
Go to the Cloud Storage browser
Navigate to the object whose ACL you want to view.
Choose Edit access from the drop down menu for the object.

You should see a permission dialog with the object's permissions.

To learn how to get detailed error information about failed Cloud Storage operations in the Google Cloud console, see Troubleshooting.

Command line

Use the objects describe command with the --format flag to retrieve an object's ACL:
```
gcloud storage objects describe gs://BUCKET_NAME/OBJECT_NAME --format="default(acl)"
```
Where:
- BUCKET_NAME is the name of the bucket containing the object whose ACL you want to view. For example, my-bucket.
- OBJECT_NAME is the name of the object whose ACL you want to view. For example, paris.jpg.

Client libraries

C++

For more information, see the Cloud Storage C++ API reference documentation.

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

The following sample gets an object ACL:

namespace gcs = ::google::cloud::storage;
using ::google::cloud::StatusOr;
[](gcs::Client client, std::string const& bucket_name,
   std::string const& object_name) {
  StatusOr<std::vector<gcs::ObjectAccessControl>> items =
      client.ListObjectAcl(bucket_name, object_name);

  if (!items) throw std::move(items).status();
  std::cout << "ACLs for object=" << object_name << " in bucket "
            << bucket_name << "\n";
  for (gcs::ObjectAccessControl const& acl : *items) {
    std::cout << acl.role() << ":" << acl.entity() << "\n";
  }
}

C#

For more information, see the Cloud Storage C# API reference documentation.

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

The following sample gets an object ACL:


using Google.Apis.Storage.v1.Data;
using Google.Cloud.Storage.V1;
using System;
using System.Collections.Generic;

public class PrintFileAclSample
{
    public IEnumerable<ObjectAccessControl> PrintObjectAcl(
        string bucketName = "your-unique-bucket-name",
        string objectName = "your-object-name")
    {
        var storage = StorageClient.Create();
        var storageObject = storage.GetObject(bucketName, objectName, new GetObjectOptions
        {
            Projection = Projection.Full
        });

        foreach (var acl in storageObject.Acl)
        {
            Console.WriteLine($"{acl.Role}:{acl.Entity}");
        }

        return storageObject.Acl;
    }
}

Go

For more information, see the Cloud Storage Go API reference documentation.

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

The following sample gets an object ACL:

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/storage"
)

// printFileACL lists ACL of the specified object.
func printFileACL(w io.Writer, bucket, object string) error {
	// bucket := "bucket-name"
	// object := "object-name"
	ctx := context.Background()
	client, err := storage.NewClient(ctx)
	if err != nil {
		return fmt.Errorf("storage.NewClient: %w", err)
	}
	defer client.Close()

	rules, err := client.Bucket(bucket).Object(object).ACL().List(ctx)
	if err != nil {
		return fmt.Errorf("ACLHandle.List: %w", err)
	}
	for _, rule := range rules {
		fmt.Fprintf(w, "ACL rule: %v\n", rule)
	}
	return nil
}

Java

For more information, see the Cloud Storage Java API reference documentation.

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

The following sample gets an object ACL:


import com.google.cloud.storage.Acl;
import com.google.cloud.storage.Blob;
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.util.List;

public class PrintFileAcl {

  public static void printFileAcl(String bucketName, String blobName) {

    // The ID to give your GCS bucket
    // String bucketName = "your-unique-bucket-name";

    // The name of the blob/file that you wish to view Acls of
    // String blobName = "your-blob-name";

    Storage storage = StorageOptions.newBuilder().build().getService();
    Blob blob = storage.get(BlobId.of(bucketName, blobName));
    List<Acl> blobAcls = blob.getAcl();

    for (Acl acl : blobAcls) {

      // This will give you the role.
      // See https://cloud.google.com/storage/docs/access-control/lists#permissions
      String role = acl.getRole().name();

      // This will give you the Entity type (i.e. User, Group, Project etc.)
      // See https://cloud.google.com/storage/docs/access-control/lists#scopes
      String entityType = acl.getEntity().getType().name();

      System.out.printf("%s: %s %n", role, entityType);
    }
  }
}

Node.js

For more information, see the Cloud Storage Node.js API reference documentation.

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

The following sample gets an object ACL:

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// The ID of your GCS bucket
// const bucketName = 'your-unique-bucket-name';

// The ID of your GCS file
// const fileName = 'your-file-name';

// Imports the Google Cloud client library
const {Storage} = require('@google-cloud/storage');

// Creates a client
const storage = new Storage();

async function printFileAcl() {
  // Gets the ACL for the file
  const [acls] = await storage.bucket(bucketName).file(fileName).acl.get();

  acls.forEach(acl => {
    console.log(`${acl.role}: ${acl.entity}`);
  });
}

printFileAcl().catch(console.error);

PHP

For more information, see the Cloud Storage PHP API reference documentation.

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

The following sample gets an object ACL:

use Google\Cloud\Storage\StorageClient;

/**
 * Print all entities and roles for an object's ACL.
 *
 * @param string $bucketName The name of your Cloud Storage bucket.
 *        (e.g. 'my-bucket')
 * @param string $objectName The name of your Cloud Storage object.
 *        (e.g. 'my-object')
 */
function get_object_acl(string $bucketName, string $objectName): void
{
    $storage = new StorageClient();
    $bucket = $storage->bucket($bucketName);
    $object = $bucket->object($objectName);
    $acl = $object->acl();
    foreach ($acl->get() as $item) {
        printf('%s: %s' . PHP_EOL, $item['entity'], $item['role']);
    }
}

Python

For more information, see the Cloud Storage Python API reference documentation.

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

The following sample gets an object ACL:

from google.cloud import storage


def print_blob_acl(bucket_name, blob_name):
    """Prints out a blob's access control list."""

    storage_client = storage.Client()
    bucket = storage_client.bucket(bucket_name)
    blob = bucket.blob(blob_name)

    for entry in blob.acl:
        print(f"{entry['role']}: {entry['entity']}")

Ruby

For more information, see the Cloud Storage Ruby API reference documentation.

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

The following sample gets an object ACL:

# The ID of your GCS bucket
# bucket_name = "your-unique-bucket-name"
# file_name   = "Name of a file in the Storage bucket"
# email       = "Google Cloud Storage ACL Entity email"

require "google/cloud/storage"

storage = Google::Cloud::Storage.new
bucket  = storage.bucket bucket_name
file    = bucket.file file_name

puts "ACL for #{file_name} in #{bucket_name}:"

file.acl.owners.each do |owner|
  puts "OWNER #{owner}"
end

file.acl.readers.each do |reader|
  puts "READER #{reader}"
end

REST APIs

JSON API

Make sure that you have OWNER permission on the object.
Retrieve the object's ACL with a GET request.

The object ACL is returned in JSON format, attached to the body of the response.

For example, to return the ACL for the object paris.jpg in the bucket example-travel-maps:

curl -X GET -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    https://storage.googleapis.com/storage/v1/b/example-travel-maps/o/paris.jpg?projection=full

You should see a response that looks like:

{
  "kind": "storage#object",
  "id": "example-travel-maps/paris.jpg/1412805837131000",
  "selfLink": "https://www.googleapis.com/storage/v1/b/example-travel-maps/o/paris.jpg",
  "name": "paris.jpg",
    "bucket": "example-travel-maps",
  ...
  "acl": [
    {
      ...
      "entity": "project-owners-867489160491",
      "role": "OWNER",
      "projectTeam": {
        "projectNumber": "867489160491",
        "team": "owners"
      },
      ...
    },
    {
      ...
      "entity": "[email protected]",
      "role": "OWNER",
      "email": "[email protected]",
      ...
    },
    {
      ...
      "entity": "[email protected]",
      "role": "READER",
      "email": "[email protected]",
      ...
    }
    ],
  "owner": {
    "entity": "[email protected]"
  },
  ...
}

You can also use the objectAccessControls resource GET method to return individual entries in an object's ACL.

XML API

Make sure that you have FULL_CONTROL permission on the bucket or object.
Retrieve the bucket or object's ACL by using the acl query string parameter in a GET Object request.

The ACLs are described in XML, attached to the body of the response.

For example, to return the ACL for the object paris.jpg in the bucket example-travel-maps:

curl -X GET -H "Authorization: Bearer $(gcloud auth print-access-token)" \
    https://storage.googleapis.com/example-travel-maps/paris.jpg?acl

You should see a response that looks like:

<?xml version="1.0" encoding="UTF-8"?>
<AccessControlList>
  <Owner>
    <ID>84fac329bceSAMPLE777d5d22b8SAMPLE77d85ac2SAMPLE2dfcf7c4adf34da46</ID>
    <Name>Owner Name</Name>
  </Owner>
  <Entries>
    <Entry>
      <Scope type="UserById">
        <ID>84fac329bceSAMPLE777d5d22b8SAMPLE77d85ac2SAMPLE2dfcf7c4adf34da46</ID>
        <Name>Name</Name>
      </Scope>
      <Permission>FULL_CONTROL</Permission>
    </Entry>
    <Entry>
      <Scope type="UserByEmail">
        <EmailAddress>[email protected]</EmailAddress>
        <Name>Jane</Name>
      </Scope>
      <Permission>FULL_CONTROL</Permission>
    </Entry>
    <Entry>
      <Scope type="GroupByEmail">
        <EmailAddress>[email protected]</EmailAddress>
      </Scope>
      <Permission>READ</Permission>
    </Entry>
  </Entries>
</AccessControlList>

You can also use the JSON GET method of the ObjectAccessControls resource to return a specific ACL entry.

What's next

Learn more about ACLs.
Learn how to simplify your access control using uniform bucket-level access.
Learn about best practices when using ACLs.