docker-variants workflow (cshum/imagor)

The docker-variants workflow from cshum/imagor, explained and optimized by Latchkey.

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Source: cshum/imagor.github/workflows/docker-variants.ymlLicense Apache-2.0View source

What it does

This is the docker-variants workflow from the cshum/imagor repository, a real project running GitHub Actions. It is shown here with attribution under its Apache-2.0 license.

Below, Latchkey shows a faster, safer version produced by its optimization engine.

The workflow

workflow (.yml)

name: docker-variants

on:
  push:
    branches:
      - master
    tags: [ 'v*.*.*' ]
    paths-ignore:
      - 'docs/**'

jobs:
  build-variants:
    name: Docker variants
    runs-on: ubuntu-latest
    if: github.repository == 'cshum/imagor'
    permissions:
      contents: read
      packages: write
    strategy:
      matrix:
        variant:
          - name: magick
            build_args: |
              BASE_IMAGE=ghcr.io/cshum/imagor-base:vips8.18.3-r13-magick
              ENABLE_MAGICK=true
          - name: mozjpeg
            build_args: |
              BASE_IMAGE=ghcr.io/cshum/imagor-base:vips8.18.3-r13-mozjpeg
    steps:
      - name: Checkout repository
        uses: actions/checkout@v6

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v4
        with:
          platforms: arm64

      - name: Setup Docker buildx
        uses: docker/setup-buildx-action@v4

      - name: Login to GitHub Container Registry
        uses: docker/login-action@v4
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract Docker metadata
        id: meta
        uses: docker/metadata-action@v6
        with:
          images: ghcr.io/cshum/imagor-${{ matrix.variant.name }}
          tags: |
            type=ref,event=branch
            type=semver,pattern={{version}}
            type=raw,value=latest,enable=${{ startsWith(github.ref, 'refs/tags/v') }}

      - name: Build and push Docker image
        uses: docker/build-push-action@v7
        with:
          context: .
          platforms: ${{ startsWith(github.ref, 'refs/tags/v') && 'linux/amd64,linux/arm64' || 'linux/amd64' }}
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          build-args: ${{ matrix.variant.build_args }}

The same workflow, on Latchkey

Removes redundant runs and caps runaway jobs. Added and changed lines are highlighted.

name: docker-variants
 
on:
  push:
    branches:
      - master
    tags: [ 'v*.*.*' ]
    paths-ignore:
      - 'docs/**'
 
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true
 
jobs:
  build-variants:
    timeout-minutes: 30
    name: Docker variants
    runs-on: latchkey-small
    if: github.repository == 'cshum/imagor'
    permissions:
      contents: read
      packages: write
    strategy:
      matrix:
        variant:
          - name: magick
            build_args: |
              BASE_IMAGE=ghcr.io/cshum/imagor-base:vips8.18.3-r13-magick
              ENABLE_MAGICK=true
          - name: mozjpeg
            build_args: |
              BASE_IMAGE=ghcr.io/cshum/imagor-base:vips8.18.3-r13-mozjpeg
    steps:
      - name: Checkout repository
        uses: actions/checkout@v6
 
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v4
        with:
          platforms: arm64
 
      - name: Setup Docker buildx
        uses: docker/setup-buildx-action@v4
 
      - name: Login to GitHub Container Registry
        uses: docker/login-action@v4
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
 
      - name: Extract Docker metadata
        id: meta
        uses: docker/metadata-action@v6
        with:
          images: ghcr.io/cshum/imagor-${{ matrix.variant.name }}
          tags: |
            type=ref,event=branch
            type=semver,pattern={{version}}
            type=raw,value=latest,enable=${{ startsWith(github.ref, 'refs/tags/v') }}
 
      - name: Build and push Docker image
        uses: docker/build-push-action@v7
        with:
          context: .
          platforms: ${{ startsWith(github.ref, 'refs/tags/v') && 'linux/amd64,linux/arm64' || 'linux/amd64' }}
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          build-args: ${{ matrix.variant.build_args }}

What changed

Run on Latchkey managed runners with one line (runs-on), which apply the fixes below automatically and self-heal transient failures. This example uses latchkey-small; pick the runner size that fits the job.
Cancel superseded runs when a branch or PR gets a newer push.
Add a job timeout so a hung step cannot burn hours of runner time.

5 third-party actions are referenced by a movable tag. Pin them to the commit SHA (Latchkey resolves and applies this automatically) so a repointed tag cannot change what runs.

What Latchkey heals here

This workflow has steps that commonly fail on transient issues (network, registries, flaky browsers). On Latchkey managed runners they are detected, retried, and self-healed instead of failing your build:

Container pulls and builds

This workflow runs 1 job (2 with the matrix expanded) per trigger. On Latchkey the same minutes cost up to 58% less than GitHub-hosted, with zero queue time.

Actions used in this workflow

actions/checkout docker/setup-qemu-action docker/setup-buildx-action docker/login-action docker/metadata-action docker/build-push-action