Configuring Access Control

This page describes the access control options available in Container Registry.

Container Registry uses a Cloud Storage bucket as the backend for serving container images. You can control who has access to your Container Registry images by adjusting permissions for the Cloud Storage bucket.

Caution: Container Registry only recognizes permissions set on the Cloud Storage bucket. Container Registry will ignore permissions set on individual objects within the Cloud Storage bucket.

You manage access control in Cloud Storage by using the GCP Console or the gsutil command-line tool. Refer to the gsutil acl and gsutil defacl documentation for more information.

Permissions and Roles

The following table explains the permissions and roles required for Container Registry actions.

Action	Permissions	Role	Role Title
Push (Read and Write)	storage.buckets.create storage.buckets.delete storage.buckets.get storage.buckets.list storage.buckets.update storage.objects.create storage.objects.delete storage.objects.get storage.objects.list storage.objects.update	roles/storage.admin	Storage Admin
Pull (Read Only)	storage.objects.get storage.objects.list	roles/storage.objectViewer	Storage Object Viewer

Granting users and other projects access to a registry

To give specific users or container clusters running on other projects permissions to pull images from a registry, you need to grant read permission on the underlying Cloud Storage bucket. The bucket which backs your images will have a [BUCKET_NAME] of the form:

• artifacts.[PROJECT-ID].appspot.com for images pushed to a registry in the host gcr.io, or

• [REGION].artifacts.[PROJECT-ID].appspot.com, where:

  • [PROJECT-ID] is your Google Cloud Platform Console project ID.
  • [REGION] is:
    • us for registries in the host us.gcr.io
    • eu for registries in the host eu.gcr.io
    • asia for registries in the host asia.gcr.io

You can grant read permission on the underlying Cloud Storage bucket using the Google Cloud Platform Console or the command line.

Console

1. Visit the Cloud Storage page in the GCP Console.

2. Select the artifacts.[PROJECT-ID].appspot.com and/or [REGION].artifacts.[PROJECT-ID].appspot.com bucket's checkboxe(s). Here, [PROJECT-ID] is the GCP project ID of the project that hosts your Container Registry and [REGION] corresponds to the [REGION].gcr.io registry hosting the image.

3. Click Permissions.

4. Click Add members.

5. From the menu that appears, fill the Members field with the email addresses of users needing read permission, separated by commas. This email address can be one of the following:

   • a Google account (for example, [e-mail])
   • a Cloud IAM service account
   • the Compute Engine default service account of another project. This account is used by the Kubernetes Engine to pull container images clusters by default. It is in the form [PROJECT_NUMBER][e-mail], where [PROJECT-NUMBER] is the GCP project number of the project that is running the Kubernetes Engine cluster.

6. From the Select a role drop-down menu's Storage category, select Storage Object Viewer.

7. Click Add.

This procedure grants the user read permission for the whole bucket.

Note: Email addresses and domains must be associated with an active Google Account or Google Apps account.

gcloud

Run the following commands in your shell or terminal window:

gsutil iam ch  [TYPE]:[EMAIL-ADDRESS]:objectViewer gs://[BUCKET_NAME]

where:

• [TYPE] can be one of the following:
  • serviceAccount, if [EMAIL-ADDRESS] specifies a service account.
  • user, if the [EMAIL-ADDRESS] is a Google account.
• [EMAIL-ADDRESS] can be one of the following:
  • a Google account (for example, [e-mail])
  • a Cloud IAM service account
  • the Compute Engine default service account of another project. This account is used by the Kubernetes Engine to pull container images clusters by default. It is in the form [PROJECT_NUMBER][e-mail], where [PROJECT-NUMBER] is the GCP project number of the project that is running the Kubernetes Engine cluster.
• [BUCKET_NAME] is the name of the Cloud Storage bucket which hosts the images, as described above.

The gsutil iam ch command changes the IAM permissions of the storage bucket where the registry is hosted. Giving an account objectViewer permissions allows the account to pull images from the registry.

Note: Email addresses and domains must be associated with an active Google Account or Google Apps account.

Serving images publicly

Container Registry is publicly accessible if the host location's underlying storage bucket is publicly accessible. Within a project, all images in each host location are either public or not. Within a project's host, it is not possible to publicly serve only specific images. If you have specific images you want to make public:

• Take care to keep them in a separate host location which you make public, or
• Create a new project to hold a publicly accessible images.

To serve container images publicly, make the repository's underlying storage bucket publicly accessible by following these steps:

1. If your image you want to serve publicly is not in Container Registry, first, push it to the registry. There must be at least one image pushed to the registry for the underlying storage bucket to exist. For instructions, see Pushing an image to a registry.

2. Find the name of the Cloud Storage bucket for that registry. To do so, list the buckets:

   gsutil ls
   

   Your Container Registry bucket URL will be listed as gs://artifacts.[PROJECT-ID].appspot.com or gs://[REGION].artifacts.[PROJECT-ID].appspot.com, where:

   • [PROJECT-ID] is your Google Cloud Platform Console project ID. See Domain-scoped projects for how to work with projects IDs that include a domain.
   • [REGION] is:
     • us for registries in the host us.gcr.io
     • eu for registries in the host eu.gcr.io
     • asia for registries in the host asia.gcr.io

3. Make the storage bucket of the Container Registry publicly accessible by running the following command. This command will make all images in the registry publicly accessible.

   gsutil iam ch allUsers:objectViewer gs://[BUCKET_NAME]
   

   where:

   • gs://[BUCKET_NAME] is the Container Registry's bucket URL

Note: Your project will be billed for the egress networking costs of serving the storage objects. Read Cloud Storage Pricing to learn more about egress traffic costs for Cloud Storage.

Pulling a publicly accessible image

When the Container Registry is publicly accessible, anyone can pull its images. For instructions, see Pulling images from a registry.

Adding new project members with Cloud Storage permissions

You can add new project members to your Google Cloud Platform project and grant them the Storage Object Viewer role.

To add new members to a project, perform the following steps:

1. Visit the IAM & Admin page in GCP Console.
2. Click Add and provide email addresses in the Members field.
3. From the Roles drop-down menu's Storage category, select Storage Object Viewer.
4. Click Add.

Note: Because adding a user to your project gives them access to all of that project's services, you may wish to grant access to the registry.

Revoking permissions for specific users

To revoke permissions for specific users, run the following command:

gsutil acl ch -d [EMAIL-ADDRESS] gs://[BUCKET_NAME]

where:

• [EMAIL-ADDRESS] is the user's email address
• [BUCKET_NAME] is the name of the desired bucket