Docker

Container Lifecycle

Command	Description
docker run [OPTIONS] IMAGE [CMD]	Create and start container
docker start CONTAINER	Start stopped container
docker stop CONTAINER	Stop running container
docker restart CONTAINER	Restart container
docker rm CONTAINER	Remove stopped container
docker exec -it CONTAINER CMD	Run command in running container
docker logs CONTAINER	View container logs

docker run -d -p 8080:80 --name web nginx
docker exec -it web /bin/sh
docker logs -f web

Images

Command	Description
docker build -t NAME:TAG .	Build image from Dockerfile
docker pull IMAGE	Pull image from registry
docker push IMAGE	Push image to registry
docker tag SOURCE TARGET	Tag image
docker rmi IMAGE	Remove image
docker images / docker image ls	List images

docker build -t myapp:latest .
docker tag myapp:latest myregistry/myapp:v1

Dockerfile Instructions

Instruction	Purpose
FROM image[:tag]	Base image
RUN cmd	Execute command (creates layer)
COPY src dest	Copy files (prefer over ADD)
ADD src dest	Copy + extract archives
WORKDIR path	Set working directory
EXPOSE port	Document port (no publish)
CMD ["exec","arg"]	Default command (overridable)
ENTRYPOINT ["exec"]	Fixed entry (always runs)
ENV KEY=value	Environment variable
ARG VAR=default	Build-time variable
VOLUME ["path"]	Mount point
HEALTHCHECK	Container health check

FROM node:20-alpine
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production
COPY . .
EXPOSE 3000
CMD ["node", "index.js"]

Multi-stage Builds

FROM node:20 AS builder
WORKDIR /app
COPY . .
RUN npm run build

FROM node:20-alpine
COPY --from=builder /app/dist ./dist
CMD ["node", "dist/index.js"]

Docker Compose

Command	Description
docker compose up -d	Start services in background
docker compose down	Stop and remove containers
docker compose ps	List services
docker compose logs -f [SERVICE]	Follow logs
docker compose exec SERVICE CMD	Run command in service

services:
  web:
    build: .
    ports:
      - "3000:3000"
    environment:
      - NODE_ENV=production
    depends_on:
      - db
  db:
    image: postgres:16
    volumes:
      - postgres_data:/var/lib/postgresql/data
    environment:
      POSTGRES_PASSWORD: secret

volumes:
  postgres_data:

networks:
  default:
    driver: bridge

Volumes

Command	Description
docker volume create NAME	Create volume
docker volume ls	List volumes
docker volume rm NAME	Remove volume
docker volume ls -q	Quiet (IDs only)

docker run -v my_data:/data alpine
docker run -v $(pwd)/data:/data alpine  # bind mount

Networking

Command	Description
docker network ls	List networks
docker network create NAME	Create network
docker network connect NET CONTAINER	Connect container
docker network inspect NET	Inspect network

docker run --network mynet alpine
docker run -p 8080:80 --name web nginx

Useful Flags

Flag	Description
-d	Detached (background)
-it	Interactive + TTY
-p HOST:CONTAINER	Port mapping
-e VAR=value	Environment variable
-v HOST:CONTAINER	Volume mount
--name NAME	Container name
--rm	Remove on exit
--restart POLICY	Restart policy (always, on-failure)

Cleanup

Command	Description
docker system prune	Remove unused data
docker system prune -a	Remove all unused images
docker system prune -a --volumes	Include volumes
docker system df	Disk usage summary

docker system prune -f
docker container prune -f
docker image prune -a -f