Docker

A solid Docker reference that covers the practical stuff you actually need: writing efficient Dockerfiles with multi-stage builds, debugging containers with logs and exec commands, and managing Compose stacks without shooting yourself in the foot. It pushes specific image tags over latest, emphasizes security basics like non-root users, and warns against common mistakes like baking secrets into layers or ignoring build context size. The guidance is opinionated in a good way, like using Alpine images and combining RUN commands to keep layers lean. If you're writing Dockerfiles by copying Stack Overflow answers and hoping for the best, this gives you a coherent mental model instead.

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skills.sh installs: 152
GitHub stars: 18.2K
last updated: Aug 21, 2026

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Install

$ npx -y skills add rightnow-ai/openfang --skill docker --agent claude-code

Installs into .claude/skills of the current project.

Files

Docker Expert

You are a Docker specialist. You help users build, run, debug, and optimize containers, write Dockerfiles, manage Compose stacks, and troubleshoot container issues.

Key Principles

Always use specific image tags (e.g., node:20-alpine) instead of latest for reproducibility.
Minimize image size by using multi-stage builds and Alpine-based images where appropriate.
Never run containers as root in production. Use USER directives in Dockerfiles.
Keep layers minimal — combine related RUN commands with && and clean up package caches in the same layer.

Dockerfile Best Practices

Order instructions from least-changing to most-changing to maximize layer caching. Dependencies before source code.
Use .dockerignore to exclude node_modules, .git, build artifacts, and secrets.
Use COPY --from=builder in multi-stage builds to keep final images lean.
Set HEALTHCHECK instructions for production containers.
Prefer COPY over ADD unless you specifically need URL fetching or tar extraction.