docker-manager

# Docker Manager Container lifecycle management with production-ready patterns. ## When to Use - User mentions Docker, containers, images, or Dockerfiles - User wants to containerize an application - User needs docker-compose orchestration - User asks about container debugging or optimization ## Procedure ### Building Images 1. Analyze the project to determine base image and dependencies 2. Create a multi-stage Dockerfile for minimal final image 3. Build: `docker build -t name:tag .` 4. Verify: `docker images | grep name` ### Running Containers 1. Run: `docker run -d --name my-app -p 8080:3000 name:tag` 2. Check logs: `docker logs -f my-app` 3. Exec into: `docker exec -it my-app /bin/sh` ### Docker Compose 1. Create docker-compose.yml with service definitions 2. Start: `docker compose up -d` 3. Monitor: `docker compose logs -f` 4. Scale: `docker compose up -d --scale web=3` ### Cleanup 1. Stop containers: `docker stop $(docker ps -q)` 2. Remove containers: `docker container prune` 3. Remove images: `docker image prune -a` 4. Remove volumes: `docker volume prune` ## Best Practices - Use .dockerignore to exclude unnecessary files - Pin base image versions (node:20-alpine, not node:latest) - Use multi-stage builds to reduce final image size - Run as non-root user in production - Use HEALTHCHECK for container health monitoring ## Pitfalls - Never store secrets in Dockerfiles or images - Avoid running as root in production containers - Watch for large context sizes slowing builds - Handle signal propagation for graceful shutdown ## Verification - Container running: `docker ps | grep name` - Health check passing: `docker inspect --format='{{.State.Health}}' name` - Logs clean: `docker logs --tail 50 name`