docker-patterns

When to Use

Trigger this skill when writing Dockerfiles, optimizing image size, configuring Docker Compose, or debugging container issues.

Core Practices

Image Optimization

• Multi-stage builds: full image for compilation, alpine/distroless for runtime
• Merge RUN layers to reduce image layers
• .dockerignore to exclude node_modules, .git, test files
• Use COPY --from=builder to copy only artifacts

Dockerfile Standards

• Pin base image versions, never use latest
• Run as non-root: RUN adduser -D appuser && USER appuser
• Health check: HEALTHCHECK --interval=30s CMD curl -f http://localhost/ || exit 1
• Default env vars: ENV NODE_ENV=production

Compose Orchestration

• Use depends_on + healthcheck for startup order
• Mount source volumes in dev, use built images in production
• Use profiles to separate dev/test/prod services
• Resource limits: deploy.resources.limits.memory/cpus

Debugging

• docker exec -it <container> sh to enter container
• docker logs -f --tail 100 <container> for logs
• Network issues: docker network inspect and nslookup