docker-registry

docker-registry

Production patterns for pushing, pulling, tagging, and managing container images in registries. Covers GitHub Container Registry (GHCR), Docker Hub, and self-hosted registries.

Tagging Strategy

A good tagging strategy enables rollback, traceability, and cache reuse.

SHA=$(git rev-parse --short HEAD)
BRANCH=$(git rev-parse --abbrev-ref HEAD | sed 's|/|-|g')
TAG_LATEST="ghcr.io/myorg/myapp:latest"
TAG_SHA="ghcr.io/myorg/myapp:${SHA}"
TAG_BRANCH="ghcr.io/myorg/myapp:${BRANCH}"

# Build once, tag multiple times
docker build -t "$TAG_LATEST" .
docker tag "$TAG_LATEST" "$TAG_SHA"
docker tag "$TAG_LATEST" "$TAG_BRANCH"

# Push all tags
docker push "$TAG_LATEST"
docker push "$TAG_SHA"
docker push "$TAG_BRANCH"

GitHub Container Registry (GHCR)

# .github/workflows/build-push.yml
name: Build and Push

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}   # e.g. myorg/myapp

jobs:
  build-push:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write

    steps:
      - uses: actions/checkout@v4

      - name: Log in to GHCR
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}   # no extra secret needed

      - name: Extract metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=sha,prefix=
            type=ref,event=branch
            type=raw,value=latest,enable=${{ github.ref == 'refs/heads/main' }}

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Build and push
        uses: docker/build-push-action@v5
        with:
          context: .
          push: ${{ github.event_name == 'push' }}   # don't push on PRs
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max