Docker build cache in CI pipelines for faster builds

CI Builds Are Slow Without Caching

Every CI run starts from a fresh runner. Without cache, every layer rebuilds from scratch — a 5-minute build on every push. GitHub Actions provides a cache backend that BuildKit can read and write between runs.

Enabling Cache in GitHub Actions

      - name: Build and push with cache
        uses: docker/build-push-action@v5
        with:
          context: .
          push: true
          tags: ghcr.io/${{ github.repository }}:${{ github.sha }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

type=gha uses GitHub Actions' native cache storage. mode=max caches all layers including intermediate ones, maximizing cache hits. On the first run the full build executes and populates the cache. Subsequent runs skip unchanged layers — the dependency install layer is typically reused unless package.json changed.

Registry-Based Cache (Alternative)

          cache-from: type=registry,ref=ghcr.io/org/app:buildcache
          cache-to: type=registry,ref=ghcr.io/org/app:buildcache,mode=max

This stores the cache as a special image tag in your registry — useful when cache size exceeds GitHub's 10GB limit or when sharing cache across different CI systems.