Docker Cheat Sheet

Cheet says: Containers make everything portable!

Basics

Run a container
docker run nginx
docker run -d nginx                    # Detached
docker run -p 8080:80 nginx            # Port mapping
docker run -v /host:/container nginx   # Volume mount
docker run --rm nginx                  # Remove when stopped
docker run -it ubuntu bash             # Interactive

List containers
docker ps           # Running
docker ps -a        # All

Stop/Start
docker stop container_id
docker start container_id
docker restart container_id

Remove
docker rm container_id
docker rm -f container_id  # Force

Images

List images
docker images

Pull image
docker pull nginx:latest

Build image
docker build -t myapp:1.0 .

Tag image
docker tag myapp:1.0 registry/myapp:1.0

Push to registry
docker push registry/myapp:1.0

Remove image
docker rmi image_id

Logs & Exec

View logs
docker logs container_id
docker logs -f container_id  # Follow

Execute command in container
docker exec -it container_id bash
docker exec container_id ls /app

Dockerfile Basics

FROM node:18-alpine
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
EXPOSE 3000
CMD ["npm", "start"]

Docker Compose

docker-compose.yml
version: '3.8'
services:
  web:
    build: .
    ports:
      - "3000:3000"
    environment:
      - NODE_ENV=production
    depends_on:
      - db

  db:
    image: postgres:15
    volumes:
      - pgdata:/var/lib/postgresql/data
    environment:
      - POSTGRES_PASSWORD=secret

volumes:
  pgdata:

Compose commands
docker compose up
docker compose up -d          # Detached
docker compose down
docker compose logs -f
docker compose ps
docker compose exec web bash

Cleanup

Remove stopped containers
docker container prune

Remove unused images
docker image prune
docker image prune -a  # All unused

Remove everything unused
docker system prune
docker system prune -a --volumes  # Nuclear option

Check disk usage
docker system df

Networking

List networks
docker network ls

Create network
docker network create mynet

Connect container to network
docker run --network mynet nginx

Inspect network
docker network inspect mynet

Volumes

List volumes
docker volume ls

Create volume
docker volume create mydata

Mount volume
docker run -v mydata:/data nginx

Inspect volume
docker volume inspect mydata

Remove volume
docker volume rm mydata

Pro Tips

Copy files to/from container
docker cp file.txt container:/path
docker cp container:/path/file.txt .

View resource usage
docker stats

Inspect container
docker inspect container_id

Save/Load images
docker save myapp > myapp.tar
docker load < myapp.tar