GitLab container registry administration

DETAILS: Tier: Free, Premium, Ultimate Offering: Self-managed

NOTE: The next-generation container registry is now available for upgrade on self-managed instances. This upgraded registry supports online garbage collection, and has significant performance and reliability improvements.

With the GitLab container registry, every project can have its own space to store Docker images.

For more details about the Distribution Registry:

This document is the administrator's guide. To learn how to use the GitLab Container Registry, see the user documentation.

Enable the container registry

The process for enabling the container registry depends on the type of installation you use.

Linux package installations

If you installed GitLab by using the Linux package, the container registry may or may not be available by default.

The container registry is automatically enabled and available on your GitLab domain, port 5050 if you're using the built-in Let's Encrypt integration.

Otherwise, the container registry is not enabled. To enable it:

You can configure it for your GitLab domain, or
You can configure it for a different domain.

The container registry works under HTTPS by default. You can use HTTP but it's not recommended and is beyond the scope of this document.

Helm Charts installations

For Helm Charts installations, see Using the Container Registry. in the Helm Charts documentation.

Self-compiled installations

If you self-compiled your GitLab installation:

You must deploy a registry using the image corresponding to the version of GitLab you are installing (for example: registry.gitlab.com/gitlab-org/build/cng/gitlab-container-registry:v3.15.0-gitlab)
After the installation is complete, to enable it, you must configure the Registry's settings in gitlab.yml.
Use the sample NGINX configuration file from under lib/support/nginx/registry-ssl and edit it to match the host, port, and TLS certificate paths.

The contents of gitlab.yml are:

registry:
  enabled: true
  host: registry.gitlab.example.com
  port: 5005
  api_url: http://localhost:5000/
  key: config/registry.key
  path: shared/registry
  issuer: gitlab-issuer

Where:

Parameter	Description
`enabled`	`true` or `false`. Enables the Registry in GitLab. By default this is `false`.
`host`	The host URL under which the Registry runs and users can use.
`port`	The port the external Registry domain listens on.
`api_url`	The internal API URL under which the Registry is exposed. It defaults to `http://localhost:5000`. Do not change this unless you are setting up an external Docker registry.
`key`	The private key location that is a pair of Registry's `rootcertbundle`.
`path`	This should be the same directory like specified in Registry's `rootdirectory`. This path needs to be readable by the GitLab user, the web-server user and the Registry user.
`issuer`	This should be the same value as configured in Registry's `issuer`.

A Registry init file is not shipped with GitLab if you install it from source. Hence, restarting GitLab does not restart the Registry should you modify its settings. Read the upstream documentation on how to achieve that.

At the absolute minimum, make sure your Registry configuration has container_registry as the service and https://gitlab.example.com/jwt/auth as the realm:

auth:
  token:
    realm: https://gitlab.example.com/jwt/auth
    service: container_registry
    issuer: gitlab-issuer
    rootcertbundle: /root/certs/certbundle

WARNING: If auth is not set up, users can pull Docker images without authentication.

Container registry domain configuration

You can configure the Registry's external domain in either of these ways:

Use the existing GitLab domain. The Registry listens on a port and reuses the TLS certificate from GitLab.
Use a completely separate domain with a new TLS certificate for that domain.

Because the container registry requires a TLS certificate, cost may be a factor.

Take this into consideration before configuring the container registry for the first time.

Configure container registry under an existing GitLab domain

If the container registry is configured to use the existing GitLab domain, you can expose the container registry on a port. This way you can reuse the existing GitLab TLS certificate.

If the GitLab domain is https://gitlab.example.com and the port to the outside world is 5050, to configure the container registry:

Edit gitlab.rb if you are using a Linux package installation.
Edit gitlab.yml if you are using a self-compiled installation.

Ensure you choose a port different than the one that Registry listens to (5000 by default), otherwise conflicts occur.

NOTE: Host and container firewall rules must be configured to allow traffic in through the port listed under the registry_external_url line, rather than the port listed under gitlab_rails['registry_port'] (default 5000).

::Tabs

:::TabTitle Linux package (Omnibus)

Your /etc/gitlab/gitlab.rb should contain the Registry URL as well as the path to the existing TLS certificate and key used by GitLab:
```
registry_external_url 'https://gitlab.example.com:5050'
```
The registry_external_url is listening on HTTPS under the existing GitLab URL, but on a different port.

If your TLS certificate is not in /etc/gitlab/ssl/gitlab.example.com.crt and key not in /etc/gitlab/ssl/gitlab.example.com.key uncomment the lines below:
```
registry_nginx['ssl_certificate'] = "/path/to/certificate.pem"
registry_nginx['ssl_certificate_key'] = "/path/to/certificate.key"
```
Save the file and reconfigure GitLab for the changes to take effect.

Validate using:

openssl s_client -showcerts -servername gitlab.example.com -connect gitlab.example.com:5050 > cacert.pem

If your certificate provider provides the CA Bundle certificates, append them to the TLS certificate file.

An administrator may want the container registry listening on an arbitrary port such as 5678. However, the registry and application server are behind an AWS application load balancer that only listens on ports 80 and 443. The administrator may remove the port number for registry_external_url, so HTTP or HTTPS is assumed. Then, the rules apply that map the load balancer to the registry from ports 80 or 443 to the arbitrary port. This is important if users rely on the docker login example in the container registry. Here's an example:

registry_external_url 'https://registry-gitlab.example.com'
registry_nginx['redirect_http_to_https'] = true
registry_nginx['listen_port'] = 5678

:::TabTitle Self-compiled (source)

Open /home/git/gitlab/config/gitlab.yml, find the registry entry and configure it with the following settings:
```
registry:
  enabled: true
  host: gitlab.example.com
  port: 5050
```
Save the file and restart GitLab for the changes to take effect.
Make the relevant changes in NGINX as well (domain, port, TLS certificates path).

::EndTabs

Users should now be able to sign in to the container registry with their GitLab credentials using:

docker login gitlab.example.com:5050

Configure container registry under its own domain

When the Registry is configured to use its own domain, you need a TLS certificate for that specific domain (for example, registry.example.com). You might need a wildcard certificate if hosted under a subdomain of your existing GitLab domain. For example, *.gitlab.example.com, is a wildcard that matches registry.gitlab.example.com, and is distinct from *.example.com.

As well as manually generated SSL certificates (explained here), certificates automatically generated by Let's Encrypt are also supported in Linux package installations.

Let's assume that you want the container registry to be accessible at https://registry.gitlab.example.com.

::Tabs

:::TabTitle Linux package (Omnibus)

Place your TLS certificate and key in /etc/gitlab/ssl/registry.gitlab.example.com.crt and /etc/gitlab/ssl/registry.gitlab.example.com.key and make sure they have correct permissions:
```
chmod 600 /etc/gitlab/ssl/registry.gitlab.example.com.*
```
After the TLS certificate is in place, edit /etc/gitlab/gitlab.rb with:
```
registry_external_url 'https://registry.gitlab.example.com'
```
The registry_external_url is listening on HTTPS.
Save the file and reconfigure GitLab for the changes to take effect.

If you have a wildcard certificate, you must specify the path to the certificate in addition to the URL, in this case /etc/gitlab/gitlab.rb looks like:

registry_nginx['ssl_certificate'] = "/etc/gitlab/ssl/certificate.pem"
registry_nginx['ssl_certificate_key'] = "/etc/gitlab/ssl/certificate.key"

:::TabTitle Self-compiled (source)

Open /home/git/gitlab/config/gitlab.yml, find the registry entry and configure it with the following settings:
```
registry:
  enabled: true
  host: registry.gitlab.example.com
```
Save the file and restart GitLab for the changes to take effect.
Make the relevant changes in NGINX as well (domain, port, TLS certificates path).

::EndTabs

Users should now be able to sign in to the container registry using their GitLab credentials:

docker login registry.gitlab.example.com

Disable container registry site-wide

When you disable the Registry by following these steps, you do not remove any existing Docker images. Docker image removal is handled by the Registry application itself.

::Tabs

:::TabTitle Linux package (Omnibus)

Open /etc/gitlab/gitlab.rb and set registry['enable'] to false:
```
registry['enable'] = false
```
Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Open /home/git/gitlab/config/gitlab.yml, find the registry entry and set enabled to false:
```
registry:
  enabled: false
```
Save the file and restart GitLab for the changes to take effect.

::EndTabs

Disable container registry for new projects site-wide

If the container registry is enabled, then it should be available on all new projects. To disable this function and let the owners of a project to enable the container registry by themselves, follow the steps below.

::Tabs

:::TabTitle Linux package (Omnibus)

Edit /etc/gitlab/gitlab.rb and add the following line:

gitlab_rails['gitlab_default_projects_features_container_registry'] = false

Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Open /home/git/gitlab/config/gitlab.yml, find the default_projects_features entry and configure it so that container_registry is set to false:

## Default project features settings
default_projects_features:
  issues: true
  merge_requests: true
  wiki: true
  snippets: false
  builds: true
  container_registry: false

Save the file and restart GitLab for the changes to take effect.

::EndTabs

Increase token duration

In GitLab, tokens for the container registry expire every five minutes. To increase the token duration:

On the left sidebar, at the bottom, select Admin.
Select Settings > CI/CD.
Expand Container Registry.
For the Authorization token duration (minutes), update the value.
Select Save changes.

Configure storage for the container registry

NOTE: For storage backends that support it, you can use object versioning to preserve, retrieve, and restore the non-current versions of every object stored in your buckets. However, this may result in higher storage usage and costs. Due to how the registry operates, image uploads are first stored in a temporary path and then transferred to a final location. For object storage backends, including S3 and GCS, this transfer is achieved with a copy followed by a delete. With object versioning enabled, these deleted temporary upload artifacts are kept as non-current versions, therefore increasing the storage bucket size. To ensure that non-current versions are deleted after a given amount of time, you should configure an object lifecycle policy with your storage provider.

WARNING: Do not directly modify the files or objects stored by the container registry. Anything other than the registry writing or deleting these entries can lead to instance-wide data consistency and instability issues from which recovery may not be possible.

You can configure the container registry to use various storage backends by configuring a storage driver. By default the GitLab container registry is configured to use the file system driver configuration.

The different supported drivers are:

Driver	Description
`filesystem`	Uses a path on the local file system
`azure`	Microsoft Azure Blob Storage
`gcs`	Google Cloud Storage
`s3`	Amazon Simple Storage Service. Be sure to configure your storage bucket with the correct S3 Permission Scopes.

Although most S3 compatible services (like MinIO) should work with the container registry, we only guarantee support for AWS S3. Because we cannot assert the correctness of third-party S3 implementations, we can debug issues, but we cannot patch the registry unless an issue is reproducible against an AWS S3 bucket.

Use file system

If you want to store your images on the file system, you can change the storage path for the container registry, follow the steps below.

This path is accessible to:

The user running the container registry daemon.
The user running GitLab.

All GitLab, Registry, and web server users must have access to this directory.

::Tabs

:::TabTitle Linux package (Omnibus)

The default location where images are stored in Linux package installations is /var/opt/gitlab/gitlab-rails/shared/registry. To change it:

Edit /etc/gitlab/gitlab.rb:

gitlab_rails['registry_path'] = "/path/to/registry/storage"

Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

The default location where images are stored in self-compiled installations is /home/git/gitlab/shared/registry. To change it:

Open /home/git/gitlab/config/gitlab.yml, find the registry entry and change the path setting:
```
registry:
  path: shared/registry
```
Save the file and restart GitLab for the changes to take effect.

::EndTabs

Use object storage

If you want to store your images on object storage, you can change the storage driver for the container registry.

WARNING: GitLab does not back up Docker images that are not stored on the file system. Enable backups with your object storage provider if desired.

Configure `s3` and `gcs` storage drivers for Linux package installations

The following configuration steps are for the s3 and gcs storage drivers. Other storage drivers are supported.

To configure the s3 storage driver for a Linux package installation:

Edit /etc/gitlab/gitlab.rb:

registry['storage'] = {
  's3' => {
    'accesskey' => 's3-access-key',
    'secretkey' => 's3-secret-key-for-access-key',
    'bucket' => 'your-s3-bucket',
    'region' => 'your-s3-region',
    'regionendpoint' => 'your-s3-regionendpoint'
  }
}

To avoid using static credentials, use an IAM role and omit accesskey and secretkey. Make sure that your IAM profile follows the permissions documented by Docker.

registry['storage'] = {
  's3' => {
    'bucket' => 'your-s3-bucket',
    'region' => 'your-s3-region'
  }
}

If using with an AWS S3 VPC endpoint, then set regionendpoint to your VPC endpoint address and set pathstyle to false:

registry['storage'] = {
  's3' => {
    'accesskey' => 's3-access-key',
    'secretkey' => 's3-secret-key-for-access-key',
    'bucket' => 'your-s3-bucket',
    'region' => 'your-s3-region',
    'regionendpoint' => 'your-s3-vpc-endpoint',
    'pathstyle' => false
  }
}

regionendpoint is only required when configuring an S3 compatible service such as MinIO, or when using an AWS S3 VPC Endpoint.
your-s3-bucket should be the name of a bucket that exists, and can't include subdirectories.
pathstyle should be set to true to use host/bucket_name/object style paths instead of bucket_name.host/object. Set to false for AWS S3.

You can set a rate limit on connections to S3 to avoid 503 errors from the S3 API. To do this, set maxrequestspersecond to a number within the S3 request rate threshold:

registry['storage'] = {
  's3' => {
    'accesskey' => 's3-access-key',
    'secretkey' => 's3-secret-key-for-access-key',
    'bucket' => 'your-s3-bucket',
    'region' => 'your-s3-region',
    'regionendpoint' => 'your-s3-regionendpoint',
    'maxrequestspersecond' => 100
  }
}

Save the file and reconfigure GitLab for the changes to take effect.

To configure the gcs storage driver for a Linux package installation:

Edit /etc/gitlab/gitlab.rb:

registry['storage'] = {
  'gcs' => {
    'bucket' => 'BUCKET_NAME',
    'keyfile' => 'PATH/TO/KEYFILE',
    # If you have the bucket shared with other apps beyond the registry, uncomment the following:
    # 'rootdirectory' => '/gcs/object/name/prefix'
  }
}

GitLab supports all available parameters.

Save the file and reconfigure GitLab for the changes to take effect.

Self-compiled installations

Configuring the storage driver is done in the registry configuration YAML file created when you deployed your Docker registry.

s3 storage driver example:

storage:
  s3:
    accesskey: 's3-access-key'                # Not needed if IAM role used
    secretkey: 's3-secret-key-for-access-key' # Not needed if IAM role used
    bucket: 'your-s3-bucket'
    region: 'your-s3-region'
    regionendpoint: 'your-s3-regionendpoint'
  cache:
    blobdescriptor: inmemory
  delete:
    enabled: true

your-s3-bucket should be the name of a bucket that exists, and can't include subdirectories.

Migrate to object storage without downtime

WARNING: Using AWS DataSync to copy the registry data to or between S3 buckets creates invalid metadata objects in the bucket. For additional details, see Tags with an empty name. To move data to and between S3 buckets, the AWS CLI sync operation is recommended.

To migrate storage without stopping the container registry, set the container registry to read-only mode. On large instances, this may require the container registry to be in read-only mode for a while. During this time, you can pull from the container registry, but you cannot push.

Optional: To reduce the amount of data to be migrated, run the garbage collection tool without downtime.
This example uses the aws CLI. If you haven't configured the CLI before, you have to configure your credentials by running sudo aws configure. Because a non-administrator user likely can't access the container registry folder, ensure you use sudo. To check your credential configuration, run ls to list all buckets.
```
sudo aws --endpoint-url https://your-object-storage-backend.com s3 ls
```
If you are using AWS as your back end, you do not need the --endpoint-url.
Copy initial data to your S3 bucket, for example with the aws CLI cp or sync command. Make sure to keep the docker folder as the top-level folder inside the bucket.
```
sudo aws --endpoint-url https://your-object-storage-backend.com s3 sync registry s3://mybucket
```
NOTE: If you have a lot of data, you may be able to improve performance by running parallel sync operations.
To perform the final data sync, put the container registry in read-only mode and reconfigure GitLab.
Sync any changes dating from after the initial data load to your S3 bucket, and delete files that exist in the destination bucket but not in the source:
```
sudo aws --endpoint-url https://your-object-storage-backend.com s3 sync registry s3://mybucket --delete --dryrun
```
After verifying the command performs as expected, remove the --dryrun flag and run the command.

WARNING: The --delete flag deletes files that exist in the destination but not in the source. If you swap the source and destination, all data in the Registry is deleted.
Verify all container registry files have been uploaded to object storage by looking at the file count returned by these two commands:
```
sudo find registry -type f | wc -l
```
```
sudo aws --endpoint-url https://your-object-storage-backend.com s3 ls s3://mybucket --recursive | wc -l
```
The output of these commands should match, except for the content in the _uploads directories and sub-directories.
Configure your registry to use the S3 bucket for storage.
For the changes to take effect, set the Registry back to read-write mode and reconfigure GitLab.

Moving to Azure Object Storage

::Tabs

:::TabTitle Linux package (Omnibus)

registry['storage'] = {
  'azure' => {
    'accountname' => '<your_storage_account_name>',
    'accountkey' => '<base64_encoded_account_key>',
    'container' => '<container_name>',
    'trimlegacyrootprefix' => true
  }
}

:::TabTitle Self-compiled (source)

storage:
  azure:
    accountname: <your_storage_account_name>
    accountkey: <base64_encoded_account_key>
    container: <container_name>
    trimlegacyrootprefix: true

::EndTabs

By default, Azure Storage Driver uses the core.windows.net realm. You can set another value for realm in the azure section (for example, core.usgovcloudapi.net for Azure Government Cloud).

Disable redirect for storage driver

By default, users accessing a registry configured with a remote backend are redirected to the default backend for the storage driver. For example, registries can be configured using the s3 storage driver, which redirects requests to a remote S3 bucket to alleviate load on the GitLab server.

However, this behavior is undesirable for registries used by internal hosts that usually can't access public servers. To disable redirects and proxy download, set the disable flag to true as follows. This makes all traffic always go through the Registry service. This results in improved security (less surface attack as the storage backend is not publicly accessible), but worse performance (all traffic is redirected via the service).

::Tabs

:::TabTitle Linux package (Omnibus)

Edit /etc/gitlab/gitlab.rb:

registry['storage'] = {
  's3' => {
    'accesskey' => '<s3_access_key>',
    'secretkey' => '<s3_secret_key_for_access_key>',
    'bucket' => '<your_s3_bucket>',
    'region' => '<your_s3_region>',
    'regionendpoint' => '<your_s3_regionendpoint>'
  },
  'redirect' => {
    'disable' => true
  }
}

Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Add the redirect flag to your registry configuration YAML file:

storage:
  s3:
    accesskey: '<s3_access_key>'
    secretkey: '<s3_secret_key_for_access_key>'
    bucket: '<your_s3_bucket>'
    region: '<your_s3_region>'
    regionendpoint: '<your_s3_regionendpoint>'
  redirect:
    disable: true
  cache:
    blobdescriptor: inmemory
  delete:
    enabled: true

Save the file and restart GitLab for the changes to take effect.

::EndTabs

Encrypted S3 buckets

You can use server-side encryption with AWS KMS for S3 buckets that have SSE-S3 or SSE-KMS encryption enabled by default. Customer master keys (CMKs) and SSE-C encryption aren't supported because this requires sending the encryption keys in every request.

For SSE-S3, you must enable the encrypt option in the registry settings. How you do this depends on how you installed GitLab. Follow the instructions here that match your installation method.

::Tabs

:::TabTitle Linux package (Omnibus)

Edit /etc/gitlab/gitlab.rb:

registry['storage'] = {
  's3' => {
    'accesskey' => '<s3_access_key>',
    'secretkey' => '<s3_secret_key_for_access_key>',
    'bucket' => '<your_s3_bucket>',
    'region' => '<your_s3_region>',
    'regionendpoint' => '<your_s3_regionendpoint>',
    'encrypt' => true
  }
}

Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Edit your registry configuration YAML file:

storage:
  s3:
    accesskey: '<s3_access_key>'
    secretkey: '<s3_secret_key_for_access_key>'
    bucket: '<your_s3_bucket>'
    region: '<your_s3_region>'
    regionendpoint: '<your_s3_regionendpoint>'
    encrypt: true

Save the file and restart GitLab for the changes to take effect.

::EndTabs

Storage limitations

There is no storage limitation, which means a user can upload an infinite amount of Docker images with arbitrary sizes. This setting should be configurable in future releases.

Change the registry's internal port

The Registry server listens on localhost at port 5000 by default, which is the address for which the Registry server should accept connections. In the examples below we set the Registry's port to 5010.

::Tabs

:::TabTitle Linux package (Omnibus)

Open /etc/gitlab/gitlab.rb and set registry['registry_http_addr']:
```
registry['registry_http_addr'] = "localhost:5010"
```
Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Open the configuration file of your Registry server and edit the http:addr value:
```
http:
  addr: localhost:5010
```
Save the file and restart the Registry server.

::EndTabs

Disable container registry per project

If Registry is enabled in your GitLab instance, but you don't need it for your project, you can disable it from your project's settings.

Use an external container registry with GitLab as an auth endpoint

WARNING: Using third-party container registries in GitLab was deprecated in GitLab 15.8 and support ended in GitLab 16.0. If you need to use third-party container registries instead of the GitLab container registry, tell us about your use cases in feedback issue 958.

If you use an external container registry, some features associated with the container registry may be unavailable or have inherent risks.

For the integration to work, the external registry must be configured to use a JSON Web Token to authenticate with GitLab. The external registry's runtime configuration must have the following entries:

auth:
  token:
    realm: https://gitlab.example.com/jwt/auth
    service: container_registry
    issuer: gitlab-issuer
    rootcertbundle: /root/certs/certbundle

Without these entries, the registry logins cannot authenticate with GitLab. GitLab also remains unaware of nested image names under the project hierarchy, like registry.example.com/group/project/image-name:tag or registry.example.com/group/project/my/image-name:tag, and only recognizes registry.example.com/group/project:tag.

Linux package installations

You can use GitLab as an auth endpoint with an external container registry.

Open /etc/gitlab/gitlab.rb and set necessary configurations:
```
gitlab_rails['registry_enabled'] = true
gitlab_rails['registry_api_url'] = "https://<external_registry_host>:5000"
gitlab_rails['registry_issuer'] = "gitlab-issuer"
```
- gitlab_rails['registry_enabled'] = true is needed to enable GitLab container registry features and authentication endpoint. The GitLab bundled container registry service does not start, even with this enabled.
- gitlab_rails['registry_api_url'] = "http://<external_registry_host>:5000" must be changed to match the host where Registry is installed. It must also specify https if the external registry is configured to use TLS.
A certificate-key pair is required for GitLab and the external container registry to communicate securely. You need to create a certificate-key pair, configuring the external container registry with the public certificate (rootcertbundle) and configuring GitLab with the private key. To do that, add the following to /etc/gitlab/gitlab.rb:
```
# registry['internal_key'] should contain the contents of the custom key
# file. Line breaks in the key file should be marked using `\n` character
# Example:
registry['internal_key'] = "---BEGIN RSA PRIVATE KEY---\nMIIEpQIBAA\n"

# Optionally define a custom file for a Linux package installation to write the contents
# of registry['internal_key'] to.
gitlab_rails['registry_key_path'] = "/custom/path/to/registry-key.key"
```
Each time reconfigure is executed, the file specified at registry_key_path gets populated with the content specified by internal_key. If no file is specified, Linux package installations default it to /var/opt/gitlab/gitlab-rails/etc/gitlab-registry.key and populates it.
To change the container registry URL displayed in the GitLab Container Registry pages, set the following configurations:
```
gitlab_rails['registry_host'] = "registry.gitlab.example.com"
gitlab_rails['registry_port'] = "5005"
```
Save the file and reconfigure GitLab for the changes to take effect.

Self-compiled installations

Open /home/git/gitlab/config/gitlab.yml, and edit the configuration settings under registry:

## Container registry

registry:
  enabled: true
  host: "registry.gitlab.example.com"
  port: "5005"
  api_url: "https://<external_registry_host>:5000"
  path: /var/lib/registry
  key: /path/to/keyfile
  issuer: gitlab-issuer

Read more about what these parameters mean.

Save the file and restart GitLab for the changes to take effect.

Configure container registry notifications

You can configure the container registry to send webhook notifications in response to events happening in the registry.

Read more about the container registry notifications configuration options in the Docker Registry notifications documentation.

WARNING: Support for the threshold parameter was deprecated in GitLab 17.0, and is planned for removal in 18.0. Use maxretries instead.

You can configure multiple endpoints for the container registry.

::Tabs

:::TabTitle Linux package (Omnibus)

To configure a notification endpoint for a Linux package installation:

Edit /etc/gitlab/gitlab.rb:

registry['notifications'] = [
  {
    'name' => 'test_endpoint',
    'url' => 'https://gitlab.example.com/api/v4/container_registry_event/events',
    'timeout' => '500ms',
    'threshold' => 5, # DEPRECATED: use `maxretries` instead.
    'maxretries' => 5,
    'backoff' => '1s',
    'headers' => {
      "Authorization" => ["AUTHORIZATION_EXAMPLE_TOKEN"]
    }
  }
]

gitlab_rails['registry_notification_secret'] = 'AUTHORIZATION_EXAMPLE_TOKEN' # Must match the auth token in registry['notifications']

NOTE: Replace AUTHORIZATION_EXAMPLE_TOKEN with a case sensitive alphanumeric string that starts with a letter. You can generate one with < /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c 32 | sed "s/^[0-9]*//"; echo

Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Configuring the notification endpoint is done in your registry configuration YAML file created when you deployed your Docker registry.

Example:

notifications:
  endpoints:
    - name: alistener
      disabled: false
      url: https://my.listener.com/event
      headers: <http.Header>
      timeout: 500
      threshold: 5 # DEPRECATED: use `maxretries` instead.
      maxretries: 5
      backoff: 1000

::EndTabs

Run the Cleanup policy now

WARNING: If you're using a distributed architecture and Sidekiq is running on a different node, the cleanup policies don't work. To fix this:

Configure the gitlab.rb file on the Sidekiq nodes to point to the correct registry URL.
Copy the registry.key file to each Sidekiq node.

For more information, see the Sidekiq configuration page.

To reduce the amount of Container Registry disk space used by a given project, administrators can set up cleanup policies and run garbage collection.

Registry Disk Space Usage by Project

To find the disk space used by each project, run the following in the GitLab Rails console:

projects_and_size = [["project_id", "creator_id", "registry_size_bytes", "project path"]]
# You need to specify the projects that you want to look through. You can get these in any manner.
projects = Project.last(100)

projects.each do |p|
   project_total_size = 0
   container_repositories = p.container_repositories

   container_repositories.each do |c|
       c.tags.each do |t|
          project_total_size = project_total_size + t.total_size unless t.total_size.nil?
       end
   end

   if project_total_size > 0
      projects_and_size << [p.project_id, p.creator&.id, project_total_size, p.full_path]
   end
end

# print it as comma separated output
projects_and_size.each do |ps|
   puts "%s,%s,%s,%s" % ps
end

To remove image tags by running the cleanup policy, run the following commands in the GitLab Rails console:

# Numeric ID of the project whose container registry should be cleaned up
P = <project_id>

# Numeric ID of a user with Developer, Maintainer, or Owner role for the project
U = <user_id>

# Get required details / objects
user    = User.find_by_id(U)
project = Project.find_by_id(P)
policy  = ContainerExpirationPolicy.find_by(project_id: P)

# Loop through each container repository
project.container_repositories.find_each do |repo|
  puts repo.attributes

  # Start the tag cleanup
  puts Projects::ContainerRepository::CleanupTagsService.new(container_repository: repo, current_user: user, params: policy.attributes.except("created_at", "updated_at")).execute
end

You can also run cleanup on a schedule.

To enable cleanup policies for all projects instance-wide, you need to find all projects with a container registry, but with the cleanup policy disabled:

# Find all projects where Container registry is enabled, and cleanup policies disabled

projects = Project.find_by_sql ("SELECT * FROM projects WHERE id IN (SELECT project_id FROM container_expiration_policies WHERE enabled=false AND id IN (SELECT project_id FROM container_repositories))")

# Loop through each project
projects.each do |p|

# Print project IDs and project full names
    puts "#{p.id},#{p.full_name}"
end

Container registry metadata database

DETAILS: Tier: Free, Premium, Ultimate Offering: Self-managed

Generally available in GitLab 17.3.

The metadata database enables many new registry features, including online garbage collection, and increases the efficiency of many registry operations. See the Container registry metadata database page for details.

Container registry garbage collection

NOTE: Retention policies in your object storage provider, such as Amazon S3 Lifecycle, may prevent objects from being properly deleted.

The container registry can use considerable amounts of storage space, and you might want to reduce storage usage. Among the listed options, deleting tags is the most effective option. However, tag deletion alone does not delete image layers, it only leaves the underlying image manifests untagged.

To more effectively free up space, the container registry has a garbage collector that can delete unreferenced layers and (optionally) untagged manifests.

To start the garbage collector, use the registry-garbage-collect command provided by gitlab-ctl.

WARNING: This command shuts down the container registry prior to the garbage collection and only starts it again after garbage collection completes. If you prefer to avoid downtime, you can manually set the container registry to read-only mode and bypass gitlab-ctl.

The time required to perform garbage collection is proportional to the container registry data size.

Prerequisites:

You must have installed GitLab by using a Linux package or the GitLab Helm chart.

Understanding the content-addressable layers

Consider the following example, where you first build the image:

# This builds a image with content of sha256:111111
docker build -t my.registry.com/my.group/my.project:latest .
docker push my.registry.com/my.group/my.project:latest

Now, you do overwrite :latest with a new version:

# This builds a image with content of sha256:222222
docker build -t my.registry.com/my.group/my.project:latest .
docker push my.registry.com/my.group/my.project:latest

Now, the :latest tag points to manifest of sha256:222222. Due to the architecture of registry, this data is still accessible when pulling the image my.registry.com/my.group/my.project@sha256:111111, though it is no longer directly accessible via the :latest tag.

Remove unreferenced layers

Image layers are the bulk of the container registry storage. A layer is considered unreferenced when no image manifest references it. Unreferenced layers are the default target of the container registry garbage collector.

If you did not change the default location of the configuration file, run:

sudo gitlab-ctl registry-garbage-collect

If you changed the location of the container registry config.yml:

sudo gitlab-ctl registry-garbage-collect /path/to/config.yml

You can also remove all untagged manifests and unreferenced layers to recover additional space.

Removing untagged manifests and unreferenced layers

By default the container registry garbage collector ignores images that are untagged, and users can keep pulling untagged images by digest. Users can also re-tag images in the future, making them visible again in the GitLab UI and API.

If you do not care about untagged images and the layers exclusively referenced by these images, you can delete them all. Use the -m flag on the registry-garbage-collect command:

sudo gitlab-ctl registry-garbage-collect -m

If you are unsure about deleting untagged images, back up your registry data before proceeding.

Performing garbage collection without downtime

To do garbage collection while keeping the container registry online, put the registry in read-only mode and bypass the built-in gitlab-ctl registry-garbage-collect command.

You can pull but not push images while the container registry is in read-only mode. The container registry must remain in read-only for the full duration of the garbage collection.

By default, the registry storage path is /var/opt/gitlab/gitlab-rails/shared/registry.

To enable the read-only mode:

In /etc/gitlab/gitlab.rb, specify the read-only mode:

registry['storage'] = {
  'filesystem' => {
    'rootdirectory' => "<your_registry_storage_path>"
  },
  'maintenance' => {
    'readonly' => {
      'enabled' => true
    }
  }
}

Save and reconfigure GitLab:
```
sudo gitlab-ctl reconfigure
```
This command sets the container registry into the read-only mode.

Next, trigger one of the garbage collect commands:

# Remove unreferenced layers
sudo /opt/gitlab/embedded/bin/registry garbage-collect /var/opt/gitlab/registry/config.yml

# Remove untagged manifests and unreferenced layers
sudo /opt/gitlab/embedded/bin/registry garbage-collect -m /var/opt/gitlab/registry/config.yml

This command starts the garbage collection. The time to complete is proportional to the registry data size.

Once done, in /etc/gitlab/gitlab.rb change it back to read-write mode:

registry['storage'] = {
  'filesystem' => {
    'rootdirectory' => "<your_registry_storage_path>"
  },
  'maintenance' => {
    'readonly' => {
      'enabled' => false
    }
  }
}

Save and reconfigure GitLab:
```
sudo gitlab-ctl reconfigure
```

Running the garbage collection on schedule

Ideally, you want to run the garbage collection of the registry regularly on a weekly basis at a time when the registry is not being in-use. The simplest way is to add a new crontab job that it runs periodically once a week.

Create a file under /etc/cron.d/registry-garbage-collect:

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# Run every Sunday at 04:05am
5 4 * * 0  root gitlab-ctl registry-garbage-collect

You may want to add the -m flag to remove untagged manifests and unreferenced layers.

Stop garbage collection

If you anticipate stopping garbage collection, you should manually run garbage collection as described in Performing garbage collection without downtime. You can then stop garbage collection by pressing Control+C.

Otherwise, interrupting gitlab-ctl could leave your registry service in a down state. In this case, you must find the garbage collection process itself on the system so that the gitlab-ctl command can bring the registry service back up again.

Also, there's no way to save progress or results during the mark phase of the process. Only once blobs start being deleted is anything permanent done.

Continuous zero-downtime garbage collection

You can run garbage collection in the background without the need to schedule it or require read-only mode, if you migrate to the metadata database.

Configure GitLab and Registry to run on separate nodes (Linux package installations)

By default, package assumes that both services are running on the same node. To get GitLab and Registry to run on a separate nodes, separate configuration is necessary for Registry and GitLab.

Configure Registry

Below you can find configuration options you should set in /etc/gitlab/gitlab.rb, for Registry to run separately from GitLab:

registry['registry_http_addr'], default set programmatically. Needs to be reachable by web server (or LB).
registry['token_realm'], default set programmatically. Specifies the endpoint to use to perform authentication, usually the GitLab URL. This endpoint needs to be reachable by user.
registry['http_secret'], random string. A random piece of data used to sign state that may be stored with the client to protect against tampering.
registry['internal_key'], default automatically generated. Contents of the key that GitLab uses to sign the tokens. They key gets created on the Registry server, but it is not used there.
gitlab_rails['registry_key_path'], default set programmatically. This is the path where internal_key contents are written to disk.
registry['internal_certificate'], default automatically generated. Contents of the certificate that GitLab uses to sign the tokens.
registry['rootcertbundle'], default set programmatically. Path to certificate. This is the path where internal_certificate contents are written to disk.
registry['health_storagedriver_enabled'], default set programmatically. Configure whether health checks on the configured storage driver are enabled.
gitlab_rails['registry_issuer'], default value. This setting needs to be set the same between Registry and GitLab.

Configure GitLab

Below you can find configuration options you should set in /etc/gitlab/gitlab.rb, for GitLab to run separately from Registry:

gitlab_rails['registry_enabled'], must be set to true. This setting signals to GitLab that it should allow Registry API requests.
gitlab_rails['registry_api_url'], default set programmatically. This is the Registry URL used internally that users do not need to interact with, registry['registry_http_addr'] with scheme.
gitlab_rails['registry_host'], for example, registry.gitlab.example. Registry endpoint without the scheme, the address that gets shown to the end user.
gitlab_rails['registry_port']. Registry endpoint port, visible to the end user.
gitlab_rails['registry_issuer'] must match the issuer in the Registry configuration.
gitlab_rails['registry_key_path'], path to the key that matches the certificate on the Registry side.
gitlab_rails['internal_key'], contents of the key that GitLab uses to sign the tokens.

Architecture of GitLab container registry

The GitLab registry is what users use to store their own Docker images. Because of that the Registry is client facing, meaning that we expose it directly on the web server (or load balancers, LB for short).

The flow described by the diagram above:

A user runs docker login registry.gitlab.example on their client. This reaches the web server (or LB) on port 443.
Web server connects to the Registry backend pool (by default, using port 5000). Since the user didn't provide a valid token, the Registry returns a 401 HTTP code and the URL (token_realm from Registry configuration) where to get one. This points to the GitLab API.
The Docker client then connects to the GitLab API and obtains a token.
The API signs the token with the registry key and hands it to the Docker client
The Docker client now logs in again with the token received from the API. It can now push and pull Docker images.

Reference: https://distribution.github.io/distribution/spec/auth/token/

Communication between GitLab and Registry

Registry doesn't have a way to authenticate users internally so it relies on GitLab to validate credentials. The connection between Registry and GitLab is TLS encrypted. The key is used by GitLab to sign the tokens while the certificate is used by Registry to validate the signature. By default, a self-signed certificate key pair is generated for all installations. This can be overridden as needed.

GitLab interacts with the Registry using the Registry private key. When a Registry request goes out, a new short-living (10 minutes) namespace limited token is generated and signed with the private key. The Registry then verifies that the signature matches the registry certificate specified in its configuration and allows the operation. GitLab background jobs processing (through Sidekiq) also interacts with Registry. These jobs talk directly to Registry to handle image deletion.

Migrate from a third-party registry

Using external container registries in GitLab was deprecated in GitLab 15.8 and the end of support occurred in GitLab 16.0. See the deprecation notice for more details.

The integration is not disabled in GitLab 16.0, but support for debugging and fixing issues is no longer provided. Additionally, the integration is no longer being developed or enhanced with new features. Third-party registry functionality might be completely removed after the new GitLab container registry version is available for self-managed (see epic 5521). Only the GitLab container registry is planned to be supported.

This section has guidance for administrators migrating from third-party registries to the GitLab container registry. If the third-party container registry you are using is not listed here, you can describe your use cases in the feedback issue.

For all of the instructions provided below, you should try them first on a test environment. Make sure everything continues to work as expected before replicating it in production.

Docker Distribution Registry

The Docker Distribution Registry was donated to the CNCF and is now known as the Distribution Registry. This registry is the open source implementation that the GitLab container registry is based on. The GitLab container registry is compatible with the basic functionality provided by the Distribution Registry, including all the supported storage backends. To migrate to the GitLab container registry you can follow the instructions on this page, and use the same storage backend as the Distribution Registry. The GitLab container registry should accept the same configuration that you are using for the Distribution Registry.

GitLab container registry administration

Enable the container registry

Linux package installations

Helm Charts installations

Self-compiled installations

Container registry domain configuration

Configure container registry under an existing GitLab domain

Configure container registry under its own domain

Disable container registry site-wide

Disable container registry for new projects site-wide

Increase token duration

Configure storage for the container registry

Use file system

Use object storage

Configure s3 and gcs storage drivers for Linux package installations

Self-compiled installations

Migrate to object storage without downtime

Moving to Azure Object Storage

Disable redirect for storage driver

Encrypted S3 buckets

Storage limitations

Change the registry's internal port

Disable container registry per project

Use an external container registry with GitLab as an auth endpoint

Linux package installations

Self-compiled installations

Configure container registry notifications

Run the Cleanup policy now

Registry Disk Space Usage by Project

Container registry metadata database

Container registry garbage collection

Understanding the content-addressable layers

Remove unreferenced layers

Removing untagged manifests and unreferenced layers

Performing garbage collection without downtime

Running the garbage collection on schedule

Stop garbage collection

Continuous zero-downtime garbage collection

Configure GitLab and Registry to run on separate nodes (Linux package installations)

Configure Registry

Configure GitLab

Architecture of GitLab container registry

Communication between GitLab and Registry

Migrate from a third-party registry

Docker Distribution Registry

Configure `s3` and `gcs` storage drivers for Linux package installations