GitHub Action to build and publish Docker Images to GitHub Container registry

Usage examples:

Build and publish Docker Image with the head tag for the develop branch

Complete workflow example

name: Build and publish

on: 
  push:
    branches:
    - "develop" # Running this workflow only for develop branch

jobs:
  build-and-publish-head:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/[email protected] # Checking out the repo

    - name: Build and publish "head" Docker image
      uses: VaultVulp/[email protected]
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }} # Provide GITHUB_TOKEN to login into the GitHub Packages
        image-name: my-cool-service # Provide Docker image name
        image-tag: head # Provide Docker image tag

Build and publish Docker Image with a latest tag for the master branch with different dockerfile

Complete workflow example

name: Build and publish

on: 
  push:
    branches:
    - "master" # Running this workflow only for master branch

jobs:
  build-and-publish-latest:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/[email protected] # Checking out the repo

    - name: Build and publish "latest" Docker image
      uses: VaultVulp/[email protected]
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }} # Provide GITHUB_TOKEN to login into the GitHub Packages
        image-name: my-cool-service # Provide only Docker image name, tag will be automatically set to latest
        dockerfile: Alternative.Dockerfile # Provide custom Dockerfile name

Build and publish Docker Image with a tag equal to a git tag

Complete workflow example

name: Build and publish

on: 
  push:
    tags:
    - "*" # Running this workflow for any tag

jobs:
  build-and-publish-tag:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/[email protected] # Checking out the repo
    
    - name: Build and publish Docker image tagged according to a git-tag
      uses: VaultVulp/[email protected]
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }} # Provide GITHUB_TOKEN to login into the GitHub Packages
        image-name: my-cool-service # Provide only Docker image name
        extract-git-tag: true # Provide flag to extract Docker image tag from git reference

Build and publish Docker Image with a different build context

Complete workflow example

name: Build and publish

on: push

jobs:
  build-and-publish-context:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/[email protected] # Checking out the repo
    
    - name: Build and publish Docker image from a different context
      uses: VaultVulp/[email protected]
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }} # Provide GITHUB_TOKEN to login into the GitHub Packages
        image-name: my-cool-service # Provide Docker image name
        build-context: ./dev # Provide path to the folder with a Dockerfile

Pulling an image before building it

Complete workflow example

name: Build and publish

on: push

jobs:
  pull-and-build-and-publish:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/[email protected] # Checking out the repo

    - name: Pull, build and publish Docker image
      uses: VaultVulp/[email protected]
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }} # Provide GITHUB_TOKEN to login into the GitHub Packages
        image-name: my-cool-service # Provide Docker image name
        pull-image: true # Provide the flag to pull image

Passing additional image tags

NB, additional-image-tags will not replace image-tag argument - additional tags will be appended to the list. If no image-tag was specified, then image will be tagged with the latest tag.

Examples

image-tag was specified:

image-name: my-cool-service
image-tags: first
additional-image-tags: second third

Action will produce one image with three tags:

• my-cool-service:first
• my-cool-service:second
• my-cool-service:third

No image-tag was specified:

In this case action will use the default latest tag.

image-name: my-cool-service
additional-image-tags: second third

Action will produce one image with three tags:

• my-cool-service:latest
• my-cool-service:second
• my-cool-service:third

Complete workflow example

name: Build and publish 

on: push

jobs:
  build-with-multiple-tags:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/[email protected] # Checking out the repo
 
    - name: Build and publish Docker image with multiple tags
      uses: VaultVulp/[email protected]
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }} # Provide GITHUB_TOKEN to login into the GitHub Packages
        image-name: my-cool-service # Provide Docker image name
        image-tags: first # if ommitted will be replaced with "latest"
        additional-image-tags: second third # two additional tags for an image

Cross-platform builds

It's possible to leverage custom-args to build images for different architectures.

Examples

One architeture

custom-args: --platform=linux/arm64 # target architecture

Multiple architetures

custom-args: --platform=linux/arm64,linux/amd64 # multiple target architectures

Complete workflow example

name: Build and publish

on: push

jobs:
  cross-platform-builds:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/[email protected] # Checking out the repo
 
    - name: Build and publish Docker image for ARM64 and AMD64 architectures at the same time
      uses: VaultVulp/[email protected]
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }} # Provide GITHUB_TOKEN to login into the GitHub Packages
        image-name: my-cool-service # Provide Docker image name
        custom-args: --platform=linux/arm64,linux/amd64 # specify target architectures via the `custom-args` agrument

Passing additional arguments to the docker build command

NB, additional arguments should be passed with the = sign istead of a (space) between argument name and values.

Correct example:

custom-args: --build-arg=some="value" 
                      # ^ this "=" is mandatory

Incorrect example:

custom-args: --build-arg some="value" 
                      # ^ this space might break the action

Complete workflow example

name: Build and publish

on: push

jobs:
  build-with-custom-args:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/[email protected] # Checking out the repo
 
    - name: Build and publish Docker image with arbitrary --build-arg(s)
      uses: VaultVulp/[email protected]
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }} # Provide GITHUB_TOKEN to login into the GitHub Packages
        image-name: my-cool-service # Provide Docker image name
        custom-args: --build-arg=some="value" --build-arg=some_other="value" # Pass some additional arguments to the docker build command

My own repo with examples

VaultVulp/test-gp-docker-action

Security considerations

You will encounter the following log message in your GitHub Actions Pipelines:

WARNING! Using --password via the CLI is insecure. Use --password-stdin.
WARNING! Your password will be stored unencrypted in /github/home/.docker/config.json.
Login Succeeded

I would like to ensure you, that I do not store your secrets, passwords, token, or any other information.

This warning informs you about the fact, that this Action passes your GitHub token via the command line argument:

docker login -u publisher -p ${DOCKER_TOKEN} ghcr.io

In a non-safe environment, this could raise a security issue, but this is not the case. We are passing a temporary authorization token, which will expire once the pipeline is completed. It would also require additional code to extract this token from the environment or docker internals, that this Action does not have.

This is the detailed explanation about the ${{ secrets.GITHUB_TOKEN }} and it's relations with the GCR.