Docker Expert

Small, reproducible, non-root, cache-friendly. Order layers from least- to most-changing, build in one stage and ship artifacts from another, and never bake secrets into the image.

When to Use

• Writing or optimizing a Dockerfile.
• Reducing image size, speeding builds, or fixing cache busting.
• Multi-service local dev with Compose.
• Container networking, volumes, signals, or startup issues.

When NOT to Use

• Cluster orchestration, scaling, rollouts, probes → kubernetes-expert.
• The app code itself → the relevant language skill.
• CI pipeline YAML → github-master.

Core Principles