Cheat sheet: Docker and Compose

Containers

docker ps                                  # running
docker ps -a                               # all, including stopped
docker run -d --name web -p 8080:80 nginx  # run in the background
docker run --rm -it ubuntu bash            # throwaway, with a terminal
docker stop web && docker start web
docker restart web
docker rm -f web                           # remove (stops it first)
docker exec -it web sh                     # get a shell inside
docker exec web cat /etc/nginx/nginx.conf  # run a command
docker cp web:/etc/nginx/nginx.conf .      # file out of the container
docker cp ./index.html web:/usr/share/nginx/html/

Logs and state

docker logs -f --tail 100 web              # last 100 lines and follow
docker logs --since 30m web
docker stats --no-stream                   # CPU and memory of all containers
docker inspect web                         # everything about the container
docker inspect -f '{{.State.Health.Status}}' web
docker inspect -f '{{json .Mounts}}' web   # where the data is mounted
docker top web                             # processes inside
docker events --since 10m                  # what happened

Images

docker images
docker pull nginx:1.27
docker build -t myapp:1.0 .
docker build --no-cache -t myapp:1.0 .
docker tag myapp:1.0 registry.example.com/myapp:1.0
docker push registry.example.com/myapp:1.0
docker rmi myapp:1.0
docker history myapp:1.0                   # which layers

Volumes and networks

docker volume ls
docker volume inspect pgdata               # Mountpoint — where the data is
docker run --rm -v pgdata:/data -v "$PWD":/backup alpine tar czf /backup/pgdata.tgz -C /data .
docker network ls
docker network inspect bridge
docker network create mynet
docker network connect mynet web

Compose

docker compose up -d                       # start (and recreate what changed)
docker compose up -d --build               # rebuild images
docker compose ps
docker compose logs -f --tail 100 app
docker compose exec app sh
docker compose restart app
docker compose pull && docker compose up -d   # update images
docker compose down                        # remove containers, volumes stay
docker compose down -v                     # and volumes — data is deleted!
docker compose config                      # final config with variables filled in
docker compose -f compose.yml -f compose.override.yml up -d
docker compose ls                          # all projects on the server

Space and cleanup

docker system df                           # space used by images, volumes, cache
docker image prune                         # untagged images
docker image prune -a                      # all unused images
docker builder prune                       # build cache
docker container prune                     # stopped containers
docker volume prune                        # volumes without containers — careful, that is data

Log limit for all containers — /etc/docker/daemon.json, then systemctl restart docker (applies to new containers):

{ "log-driver": "json-file", "log-opts": { "max-size": "10m", "max-file": "5" } }

rs clean does all of this step by step. Turn docker run into compose — the converter.