docker-publish.yml

name: Docker

# GitHub Actions workflow for building, tagging, and pushing Docker images,
# with version signing using cosign.

on:
  push:
    branches: [ "main" ]
    tags: [ 'v*.*.*' ]

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  build:

    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      id-token: write

    steps:
      - name: Checkout repository
        uses: actions/checkout@v3

      - name: Install cosign
        uses: sigstore/cosign-installer@v3.1.1
        with:
          cosign-release: 'v2.1.1'

      - name: Setup Docker buildx
        uses: docker/setup-buildx-action@v2

      - name: Log into registry ${{ env.REGISTRY }}
        uses: docker/login-action@v2
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract Docker metadata
        id: meta
        uses: docker/metadata-action@v4
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}

      - name: Build and push Docker image
        id: build-and-push
        uses: docker/build-push-action@v4
        with:
          context: .
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

      - name: Sign the published Docker image
        env:
          TAGS: ${{ steps.meta.outputs.tags }}
          DIGEST: ${{ steps.build-and-push.outputs.digest }}
        run: echo "${TAGS}" | xargs -I {} cosign sign --yes {}@${DIGEST}