Docker Management

Use this for container lifecycle operations, Compose stacks, image builds, logs, disk cleanup, and Dockerfile review.

First Checks

docker --version
docker compose version
docker info

If Docker is not running, stop and report that instead of guessing.

Common Tasks

Task	Command
Running containers	docker ps
All containers	docker ps -a
Logs	docker logs --tail 100 <name>
Follow logs	docker logs --tail 100 -f <name>
Shell	docker exec -it <name> /bin/sh
Inspect	docker inspect <name>
Stats	docker stats --no-stream
Compose status	docker compose ps
Compose logs	docker compose logs --tail 100
Disk usage	docker system df

Debugging Flow

1. Identify the failing container or service.
2. Check status and exit code with docker ps -a or docker compose ps.
3. Read logs from the failing service only.
4. Inspect env, mounts, ports, healthcheck, restart policy, and network.
5. Reproduce with the smallest command or Compose service.
6. Fix the image/config and rebuild.

Dockerfile Review

Check for:

• Pinned base image and runtime versions.
• Multi-stage builds for compiled/bundled apps.
• No secrets in ARG, ENV, layers, or copied files.
• Non-root runtime user.
• Small runtime image and explicit healthcheck where useful.
• Dependency install before source copy when caching matters.

Cleanup Safety

Never run destructive cleanup without checking impact:

docker system df
docker image prune
docker container prune

Ask before docker system prune -a --volumes; it can remove data and rebuild caches.