How to Cache Docker Layers in GitHub Actions

Rebuilding every Docker layer on every run is slow and wasteful. BuildKit caching reuses what did not change.

Use Buildx with a cache backend so unchanged layers are restored instead of rebuilt.

With the GitHub Actions cache backend

- uses: docker/setup-buildx-action@v3
- uses: docker/build-push-action@v6
  with:
    push: true
    tags: myimage:latest
    cache-from: type=gha
    cache-to: type=gha,mode=max

Tips

• Order your Dockerfile so rarely-changing layers (deps) come before frequently-changing ones (source).
• Use multi-stage builds and copy only artifacts into the final stage.
• A registry-backed cache (ECR/GHCR) persists across runners better than local cache.

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