lsst-sqre/build-and-push-to-ghcr

A composite GitHub Actions action that builds a Docker image, tags it based on the current Git branch/tag, and pushes it to ghcr.io.

Usage

name: CI

"on":
  merge_group: {}
  pull_request: {}
  push:
    tags:
      - "*"

jobs:
  build:
    runs-on: ubuntu-latest

    # (optional) only build on tags or ticket branches
    if: >
      startsWith(github.ref, 'refs/tags/')
      || startsWith(github.head_ref, 'tickets/')

    steps:
      - uses: actions/checkout@v3

      - uses: lsst-sqre/build-and-push-to-ghcr@v1
        id: build
        with:
          image: ${{ github.repository }} # e.g. lsst-sqre/safirdemo
          github_token: ${{ secrets.GITHUB_TOKEN }}

      - run: echo Pushed ghcr.io/${{ github.repository }}:${{ steps.build.outputs.tag }}

By default, ghcr.io packages are named after the GitHub repository. To automatically set that, the above example uses the context variable ${{ github.repository }} as the image name.

Action reference

Inputs

• image (string, required) the name of the image to build and push. The image does not include the registry (ghcr.io/) or the tag. For example, the image input for ghcr.io/owner/repo:tag image is owner/repo.

• github_token (string, required) the GitHub token to use for pushing to ghcr.io. Default is ${{ secrets.GITHUB_TOKEN }}.

• dockerfile (string, optional) the path to the Dockerfile to build. Default is Dockerfile.

• context (string, optional) the Docker build context. Default is ..

• push (boolean, optional) a flag to enable pushing to ghcr.io. Default is true. If false, the action skips the push to ghcr.io, but still builds the image with docker build.

• platforms (list, optional) List of target platform for build.

• target (string, optional) the name of a build stage in the Dockerfile to target for the image. This allows multiple images built from a single Dockerfile, e.g., "runtime-A" and "runtime-B".

• build-args (list, optional) A list of build-arguments as newline-delimited arg=value string pairs. These may be specified in the Dockerfile as ARG statements.

• additional-tags (list, optional) A newline-delimited list of additional tags to be added to the built image. These can be string literals or can conform to the docker/metadata-action tags grammar.

Outputs

• fully_qualified_image_digest (string) A complete, unique, and immutable identifier for the built image, e.g. ghcr.io/owner/repo@sha256:4dcaf15076e027f272dc8aba14b1bab77fec44f8aac94c94f1b01ceee8d099d4. This string may be used to reference the built image in docker pull, docker run, etc.
• tag (string) the tag of the image that was pushed to ghcr.io.

Developer guide

This repository provides a composite GitHub Action, a type of action that packages multiple regular actions into a single step. We do this to make the GitHub Actions of all our software projects more consistent and easier to maintain. You can learn more about composite actions in the GitHub documentation.

Create new releases using the GitHub Releases UI and assign a tag with a semantic version, including a v prefix. Choose the semantic version based on compatibility for users of this workflow. If backwards compatibility is broken, bump the major version.

When a release is made, a new major version tag (i.e. v1, v2) is also made or moved using nowactions/update-majorver. We generally expect that most users will track these major version tags.