At Blacksmith, Docker is the go-to for GitHub Action workflows, whether setting up containers for tests or custom images for registries. A vital part of a healthy CI pipeline is an effective caching strategy to avoid rebuilding dependencies. Surprisingly, there are three ways to implement caching in GitHub Actions with quirks to consider. Docker images are layered, with each layer containing filesystem changes to prevent duplication. The best Dockerfiles stack layers from least to most mutated for efficient reuse. Understanding caching options like GitHub’s cache and registry-backed cache can improve workflow speed significantly. Blacksmith offers upcoming features like Docker layer caching, collocated mirrors, and remote builders for optimized CI jobs.
https://blacksmith.sh/blog/cache-is-king-a-guide-for-docker-layer-caching-in-github-actions