Docker Basics

A container is a process with its own filesystem view and isolation rules, not a tiny server you never need to inspect. When something fails, start with the container’s state and logs instead of rebuilding the image immediately.

Find out what stopped

Run docker ps -a to see containers that have exited, then docker logs <container> to read their output. With Compose, docker compose ps and docker compose logs <service> keep the focus on the service you named. An exit code tells you the process stopped; the logs may explain why.

Keep build, run, and data separate

A Dockerfile describes how to build an image. Compose describes how services run together: ports, environment, volumes, and dependencies. A volume is where data can outlive a container; deleting and recreating a container does not restore data you never stored outside its writable layer. Review generated configurations before using them, especially mounts and environment variables.

Related tools

• Docker Logs Grep — Filter docker compose logs with grep-style context lines, invert and dedupe modes.
• Docker Run to Compose — Turn a docker run command into a docker-compose service.
• Dockerfile Builder — Build a Dockerfile from a form, with multi-stage presets for Node, Python, Go, Nginx and more.