Docker Cheatsheet 01 — Docker Basics

docker run nginx                              # run + foreground
docker run -d nginx                           # detached
docker run -d --name web nginx                # named
docker run -d -p 8080:80 nginx                # publish port
docker run -d -p 127.0.0.1:8080:80 nginx      # bind to localhost
docker run --rm alpine echo hi                # remove after exit
docker run -it ubuntu bash                    # interactive shell
docker run -e ENV=prod app                    # env var
docker run --env-file .env app                # env file
docker run -v $(pwd):/app app                 # bind mount
docker run -v data:/var/lib/data app          # named volume
docker run --network mynet app                # custom network
docker run --memory=512m --cpus=1 app         # resource limits
docker run --restart=unless-stopped app

docker ps                                     # running
docker ps -a                                  # all
docker ps -a --format "table {{.ID}}\t{{.Names}}\t{{.Status}}"

docker logs web
docker logs -f web                            # follow
docker logs --tail 100 web
docker logs --since 5m web

docker exec -it web bash
docker exec web ls /
docker exec -e VAR=x web env

docker stop web
docker stop web -t 30                         # wait 30s before SIGKILL
docker start web
docker restart web
docker rm web                                 # must be stopped
docker rm -f web                              # force
docker rm $(docker ps -aq)                    # remove all

docker images
docker pull nginx
docker pull nginx:1.27-alpine
docker rmi nginx
docker image prune                            # remove dangling
docker image prune -a                         # remove unused

docker tag nginx myregistry/nginx:v1
docker push myregistry/nginx:v1

docker history nginx                          # show layers
docker inspect nginx

docker build .
docker build -t myapp .
docker build -t myapp:v1 .
docker build -f Dockerfile.prod -t myapp .
docker build --build-arg VERSION=1.0 .
docker build --no-cache .
docker build --target builder .              # multi-stage stop
docker build --platform linux/amd64,linux/arm64 .

docker inspect web
docker inspect --format='{{.NetworkSettings.IPAddress}}' web
docker inspect --format='{{json .Config.Env}}' web | jq

docker stats
docker stats --no-stream
docker top web                                # processes inside container

docker system df                              # disk usage
docker system prune                           # safe cleanup
docker system prune -a                        # also unused images
docker system prune --volumes                 # also unused volumes (DANGER)

docker volume prune
docker network prune
docker container prune

docker cp file.txt web:/app/file.txt
docker cp web:/app/log.txt ./log.txt

docker network ls
docker network create mynet
docker network inspect mynet
docker run --network mynet --name a alpine
docker run --network mynet --name b alpine ping a   # DNS resolves by name
docker network connect mynet web
docker network rm mynet

docker volume ls
docker volume create data
docker volume inspect data
docker volume rm data
docker run -v data:/app/data app              # named volume
docker run -v $(pwd)/local:/app:ro app        # bind mount, read-only
docker run --mount type=bind,src=/path,dst=/app app
docker run --mount type=tmpfs,dst=/tmp app    # tmpfs (RAM)

docker inspect --format='{{.State.Health.Status}}' web

HEALTHCHECK --interval=30s --timeout=3s --retries=3 \
    CMD curl -f http://localhost/health || exit 1

docker save -o myapp.tar myapp:v1
docker load -i myapp.tar

docker export web > web.tar
docker import web.tar mywebimage