GitHub Container Registry Image Cleanup Action

A workflow action that deletes images from the GitHub Container Registry (ghcr.io).

It includes the following features:

Multi-architecture image support
Automatic GitHub user/organization repository support
Deleting images by tag names
Deleting untagged images
Keeping a number of untagged images
Keeping a number of tagged images
Untagging of multi-tagged images
Multiple package execution
Referrers/GitHub attestation support (OCIv1 tag approach)
Sigstore cosign support
Retry and throttle support for the GitHub API calls
Validation mode to verify multi-architecture & referrers images

Setup

Setup token permissions

To allow the injected GITHUB_TOKEN secret to have access to delete images it requires its permissions to have been set correctly, either by:

In the GitHub site, Settings > Actions > General, set the Workflow permissions option to "Read and write permissions".

or by setting the permissions directly in the workflow by setting the packages value to write.

jobs:
  delete-untagged-images:
    name: Delete Untagged Images
    runs-on: ubuntu-latest
    permissions:
      packages: write

Define the action

The most basic setup with no delete or keep options deletes all untagged images from the repository. Deleting a multi-architecture image will also delete the underlying child images.

To get started add an action definition to a workflow file.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          dry-run: true

The action calls both the registry API (ghcr.io) and the GitHub package API to facilitate support for multi-architecture images. This is required to determine the relationships between all of the multi-architecture image contents. It downloads the manifest descriptors of all images and maps their content to the underlying packages. Which for multi-architecture images the underlying packages appear as untagged in GitHub (as seen in the web interface). To safely delete untagged images the action determines first if the untagged package is actually in use by another image/package and skips these. Likewise to delete an image it needs to delete all of the underlying packages.

In the above example the package and repository information will be retrieved dynamically from the action/project environment.

Do a dry-run first

It's recommended to test the cleanup action first by setting the dry-run: true option on the action and then reviewing the workflow log. This mode will simulate the cleanup action but will not delete any images/packages. This is especially important when using a wildcard/regular expression syntaxes or the older-than option to select images.

Action Options

Repository Options

Option	Required	Defaults	Description
token	yes	secrets.GITHUB_TOKEN	Token used to connect with ghcr.io and the Package API
owner	no	project owner	The GitHub repository owner, can be an organization or user type
repository	no	repository name	The GitHub repository name
package(s)	no	repository name	Comma-separated list of packages to cleanup. Supports dynamic packages (wildcard or regular expression) by enabling the `expand-packages` option. Can be used as `package` or `packages`
expand-packages	no	false	Enable wildcard or regular expression support on the `package(s)` option to support dynamic package selection. If set to true the token value must be set to a Personal Access Token (PAT).

If the owner, repository or package options are not set then the values are automatically set from the project environment where the action is running.

Cleanup Options

Option	Required	Defaults	Description
delete-tags	no		Comma-separated list of tags to delete (supports wildcard syntax), can be abbreviated as `tags`. A regular expression selector can be used instead by setting the `use-regex` option to true
exclude-tags	no		Comma-separated list of tags strictly to be preserved/excluded from deletion (supports wildcard syntax). A regular expression selector can be used instead by setting the `use-regex` option to true
delete-untagged	no	depends*	Delete all untagged images
keep-n-untagged	no		Number of untagged images to keep, sorted by date, keeping the latest
keep-n-tagged	no		Number of tagged images to keep, sorted by date, keeping the latest
delete-ghost-images	no	false	Delete multi-architecture images where all underlying platform images are missing
delete-partial-images	no	false	Delete multi-architecture images where some (but not all) underlying platform images are missing
delete-orphaned-images	no	false	Delete tagged images which have no parent (e.g. referrers and cosign tags missing their parent)
older-than	no		Only include images for processing that are older than this interval (eg 5 days, 6 months or 1 year)

* If no delete or keep options are set on the action then the action defaults the option delete-untagged to "true" and will delete all untagged images.

Other Options

Option	Required	Defaults	Description
use-regex	no	false	If set to true, the `delete-tags`,`exclude-tags` and `package` options expect a regular expression selector (if they are set)
dry-run	no	false	Simulate a cleanup action but does not make any changes (true/false)
validate	no	false	Validate all multi-architecture images in the registry after cleanup
log-level	no	info	The log level (error/warn/info/debug)

Delete Options

`delete-tags`

Comma-separated list of tags to delete (supports a wildcard syntax). Can be abbreviated as tags. Use this option to delete specific tags in the package repository.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          delete-tags: mytag*,dev # same as tags: mytag*,dev

If a tag to be deleted links to an image with multiple tags the action will unlink the tag before is deleted, effectively untagging the image. But the underlying image will not be deleted (unless all of its additional tags have been deleted also).

The option can make use of a simple wildcard syntax to match multiple images. See the wildcard-match project for its syntax. It supports the ?, * and ** wildcard characters.

To use a regular expression instead of a comma-seperated list set the use-regex option to true.

Tag values can additionaly be expressed in the sha256: digest string format.

`delete-untagged`

This option deletes all untagged images from package repository. It is the same as the default mode, however, this option can be combined with any of the other options (except for the keep-n-untagged).

Note: Untagged here means untagged images not untagged packages (in GitHub). So after running this option on repositories with multi-architecture images there could still be untagged packages showing in GitHub.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          delete-untagged: true

`exclude-tags`

This option is used to exclude tagged images from being deleted. Use it to exclude tags when combined with other options. It takes priority over all other options.

The option can make use of a simple wildcard syntax to match multiple images. See the wildcard-match project for its syntax. It supports the ?, * and ** wildcard characters.

To use a regular expression instead of a comma-seperated list set the use-regex option to true.

Tag values can additionaly be expressed in the sha256 digest string format.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          exclude-tags: dev,latest,pr*
          keep-n-tagged: 10

`older-than`

To limit the action to images that are older than a certain time this setting can be used. Set this option to a relative date value from now. This option can be used with all of the delete and keep options narrowing their scope to which images they will process.

The syntax supports the following units in the plural and singular forms: seconds, minutes, hours, days, weeks, months and years.

The option uses a simple human-interval syntax to match images. See the human-interval project for more information.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          older-than: 1 year
          keep-n-tagged: 10

In the example above the action will keep all tagged images younger than 1 year and 10 tagged images that are older than 1 year. Any additional images older than one year it will delete. All untagged images will be kept in the above example.

`delete-ghost-images` and `delete-partial-images`

These options clean up invalid multi-architecture images. They are intended to assist in cleaning up repositories that have been corrupted. Use the validate option first to identify the images which are not valid.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          delete-ghost-images: true

`delete-orphaned-images`

This option removes tagged images where the assoicated parent image does not exist. It searches for images with tags starting with "sha256-" and then searches for the equivalent sha256: digest. If an image digest is not found then it's flagged for deletion. This picks up orphaned referrers and cosign images.

Keep Options

`keep-n-untagged`

Includes for deletion all untagged images but excludes (keeps) a number of them. The value of this option sets the number of untagged images to keep. Untagged images are sorted by date and the most recent untagged images are kept. May be combined with other delete options (except the delete-untagged option).

Note: Untagged here means untagged images not untagged packages in GitHub.

jobs:
  - name: ghcr cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          keep-n-untagged: 3

Setting keep-n-untagged to 0 has the same effect as setting the delete-untagged option to true, deleting all untagged images.

`keep-n-tagged`

Includes for deletion all tagged images but excludes (keeps) a number of them. The value of this option sets the number of tagged images to keep. Tagged images are sorted by date and the most recent tagged images are kept. May be combined with other delete options.

jobs:
  - name: ghcr cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          keep-n-tagged: 3

This option operates on all tagged entries. To narrow it's scope use the exclude-tag option also.

Personal Access Tokens (PAT's)

The default injected token (secret.GITHUB_TOKEN) is sufficient for packages which have been created by a repository project pipeline (or the package has been setup to grant admin access to it). For setups where the action is accessing a package in a different repository or dynamic package selection is being used (expand-packages is set to true) a Personal Access Token (PAT) is required for the token.

The PAT should be setup as a Classic token. This is due to the GitGub Registry API currently only supporting Classic tokens. The token should be setup with both write:packages and delete:packages scopes.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          token: ${{ secrets.MY_PAT }}

Multiple Package Support

The package (or packages) options can be set to a comma separated list of packages to operate on.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          packages: myimage1,myimage2

To utilize a wildcard set the expand-packages option to true and utilize a PAT for the token.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          packages: myimage*,someotherimage
          expand-packages: true
          token: ${{ secrets.MY_PAT }}

A regular expression can be used alternatively. This requires the use-regex option to be set to true.

jobs:
  - name: ghcr.io cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          packages: '^myimage[12]$'
          expand-packages: true
          use-regex: true
          token: ${{ secrets.MY_PAT }}

Sample Action Setups

Complex example `keep-n-tagged`

Simulates how to keep 10 tagged images as well as the dev image. Additionally deletes all untagged images. Also removes multi-arch containers that are missing some or all underlying packages.

jobs:
  - name: ghcr cleanup action
    runs-on: ubuntu-latest
    steps:
      - name: 'Clean up docker images'
        uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          dry-run: true
          keep-n-tagged: 10
          exclude-tags: dev
          delete-untagged: true
          delete-partial-images: true

Delete all untagged images and keep 3 latest (rc) images

This sample operates on multiple packages and makes use of a regular expression selector. It excludes all versioned images and the latest and main tags from processing.

cleanup-images:
  name: cleanup-images
  runs-on: ubuntu-latest
  concurrency:
    group: cleanup-images
  steps:
    - uses: dataaxiom/ghcr-cleanup-action@v1
      with:
        packages: 'tiecd/k8s,tiecd/okd,tiecd/gke,tiecd/eks,tiecd/aks,tiecd/node18,tiecd/node20'
        delete-untagged: true
        keep-n-tagged: 3
        exclude-tags: "^\\d+\\.\\d+\\.\\d+$|^latest$|^main$"
        use-regex: true

Delete an image when a pull request is closed

name: Cleanup Pull Request Images
on:
  pull_request:
    types: [closed]
jobs:
  ghcr-cleanup-image:
    name: ghcr cleanup action
    runs-on: ubuntu-latest
    steps:
      - name: Delete image
        uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          delete-tags: pr-${{github.event.pull_request.number}}

Daily image cleanup of untagged images

name: Daily Image Cleanup
on:
  # every day at 01:30am
  schedule:
    - cron: '30 1 * * *'
  # or manually
  workflow_dispatch:
jobs:
  ghcr-cleanup-image:
    name: ghcr cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1

Override default owner/repository/package

The default settings will use the current project to determine the owner, repository and package names but for cross-project and multiple package support these can be overridden by setting the owner, repository and package options.

The example below uses a regular expression as the selector for the delete-tags option.

jobs:
  - name: ghcr cleanup action
    runs-on: ubuntu-latest
    steps:
      - uses: dataaxiom/ghcr-cleanup-action@v1
        with:
          owner: dataaxiom
          repository: tiecd
          package: tiecd
          delete-tags: '^mytag[12]$'
          use-regex: true

Cleanup Algorithm

The high level processing of the action occurs as follows:

For each package.
Download all package metadata and their manifests and put them into a working 'filter set'.
Remove all child images from the working filter set (including referrers and cosign images).
Remove exclude-tags images from filter set.
Remove images which are younger than the older-than option from the filter set.
Stage for deletion delete-tags images present in the filter set.
Stage for deletion delete-ghost-images, delete-partial-iamges and delete-orphaned-images images present in the filter set.
Process keep-n-tagged images from the filter set, stage remainder tagged images for deletion.
Process keep-n-untagged images from the filter set, stage remainder untagged images for deletion.
Or process delete-untagged, staging all untagged images in filter set for deletion.
Preform the deletion on all staged packages, including their children if present.

Operations

Effect on image download counts

To ensure the integrity of all images in the package repository all of of the image manifests are required to be downloaded and cross-referenced each time the action is run. The effect of this is that it will increase the package download count showing in GitHub for all packages by one. The action does not download the underlying package itself, just the manifests. But GitHub uses that event to mark it as a download.

Concurrency

The action is not designed to be run in parallel on the same package repository. Due to the nature of the cleanup process and determining what can be safely deleted it requires that no other package publishing or deleting process is occurring at the same time. It's recommended to use a GitHub concurrency group with this action in complex/busy repositories.

cleanup-images:
  name: cleanup-images
  runs-on: ubuntu-latest
  concurrency:
    group: cleanup-images
  steps:
    - uses: dataaxiom/ghcr-cleanup-action@v1

Validate Option

Set the validate option to true to enable a full scan of the image repository at the end of the execution to check that all multi-architecture images have no missing platform images. Warnings will be outputted if there are missing packages.

Packages Downloaded More Than 5000 Times

Public packages that have been downloaded more than 5000 times are prohibited by GitHub from being deleted. Currently the only way to exclude these is set the exclude-tags for these images so that they are not processed by the action.

There is currently no public GitHub API to retrieve the download counts, which would be required to programmatically remove these from been processed by the action.

Package Restoration

GitHub has a package restoration API capability. The package IDs are printed in the workflow log where the ghcr-cleanup-action is run.

Restore Organization Package

Restore User Package

Name		Name	Last commit message	Last commit date
Latest commit History 142 Commits
.devcontainer		.devcontainer
.github		.github
badges		badges
citester		citester
dist		dist
script		script
src		src
tests		tests
.eslintignore		.eslintignore
.gitignore		.gitignore
.node-version		.node-version
.prettierignore		.prettierignore
.prettierrc.json		.prettierrc.json
CONTRIBUTING.md		CONTRIBUTING.md
LICENSE		LICENSE
README.md		README.md
action.yml		action.yml
package-lock.json		package-lock.json
package.json		package.json
tsconfig.json		tsconfig.json

License

dataaxiom/ghcr-cleanup-action

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GitHub Container Registry Image Cleanup Action

Setup

Setup token permissions

Define the action

Do a dry-run first

Action Options

Repository Options

Cleanup Options

Other Options

Delete Options

delete-tags

delete-untagged

exclude-tags

older-than

delete-ghost-images and delete-partial-images

delete-orphaned-images

Keep Options

keep-n-untagged

keep-n-tagged

Personal Access Tokens (PAT's)

Multiple Package Support

Sample Action Setups

Complex example keep-n-tagged

Delete all untagged images and keep 3 latest (rc) images

Delete an image when a pull request is closed

Daily image cleanup of untagged images

Override default owner/repository/package

Cleanup Algorithm

Operations

Effect on image download counts

Concurrency

Validate Option

Packages Downloaded More Than 5000 Times

Package Restoration

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