Everyday Docker CLI

Docker has a massive surface area, but your day-to-day workflow only relies on a handful of commands. here is the essential cheat sheet for running, debugging, and cleaning up. 1. Running Containers ( docker run ) The docker run command is your workhorse. By combining a few key flags, you can control exactly how your container behaves. Run in the background with a specific name: docker run -d --name my-cache redis:7-alpine -d runs the container in detached mode (background). --name gives it a recognizable name instead of a random hash. Expose ports securely (Localhost only): docker run -p 127.0.0.1:8080:80 nginx:alpine Maps port 80 inside the container to port 8080 on your host machine, restricting access strictly to your local loopback address. Inject Environment Variables: # Single variable docker run -e ENV = prod python:3.12-slim # From a file docker run --env-file .env python:3.12-slim Auto-cleanup for one-off tasks: docker run --rm python:3.12-slim python -c "print('Done!')" --rm ensures the container is automatically deleted from your system the moment it stops running. 2. Debugging and Interacting Once a container is running, you need visibility into what it's doing. Stream live logs: docker logs -f my-cache The -f (follow) flag streams the logs in real-time. Use Ctrl+C to exit. Drop into a shell of an already running container: docker exec -it my-cache sh Unlike docker run (which creates a new container), exec opens an interactive ( -it ) shell inside an existing one. 3. Container Lifecycle Knowing how to stop a container properly prevents data corruption and hanging processes. Graceful shutdown: docker stop my-cache Sends a SIGTERM signal, giving the container time to save state and shut down cleanly. Force shutdown (when frozen): docker kill my-cache Sends an immediate SIGKILL signal. Use this only when stop fails. 4. Visibility and Cleanup Docker accumulates stopped containers and unused images fast. Keep your system clean. List all containers (including