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Docker Commands Cheat Sheet

Docker reference with containers, images, Compose, volumes, networking, and Dockerfile instructions. Copy-ready commands.

67 entries 6 sections

Images

Command Description Example
Build image from Dockerfile docker build -t myapp:latest .
Download image from registry docker pull node:20-alpine
Push image to registry docker push myrepo/myapp:1.0
List all local images docker images --filter 'dangling=true'
Remove an image docker rmi myapp:latest
Tag an image docker tag myapp:latest myrepo/myapp:1.0
Remove unused images docker image prune -a
Show image layer history docker history myapp:latest
Show image details as JSON docker inspect node:20

Containers

Command Description Example
Create and start container docker run -d -p 3000:3000 myapp
Run container in background docker run -d --name web nginx
Map port host→container docker run -p 8080:80 nginx
Mount volume docker run -v ./data:/app/data myapp
Set environment variable docker run -e NODE_ENV=production myapp
Load env vars from file docker run --env-file .env myapp
Assign name to container docker run --name api myapp
Auto-remove on exit docker run --rm -it node:20 node
Interactive shell in container docker run -it ubuntu bash
Connect to network docker run --network mynet myapp
List running containers docker ps -a (include stopped)
Stop running container docker stop web
Start stopped container docker start web
Restart container docker restart api
Remove stopped container docker rm -f web
Run command in running container docker exec -it web bash
View container logs docker logs -f --tail 100 web
Copy files to/from container docker cp ./config.json web:/app/
Live resource usage stats docker stats web api db
Show running processes docker top web
Remove all stopped containers docker container prune -f

Dockerfile

Command Description Example
Base image for the build FROM node:20-alpine
Set working directory WORKDIR /app
Copy files into image COPY package*.json ./
Copy with URL/tar extraction support ADD https://example.com/file.tar.gz /tmp/
Execute command during build RUN npm ci --production
Default command when container starts CMD ["node", "server.js"]
Fixed command (CMD becomes args) ENTRYPOINT ["node"]
Set environment variable ENV NODE_ENV=production
Document which port app uses EXPOSE 3000
Build-time variable ARG NODE_VERSION=20
Create mount point VOLUME ["/data"]
Set user for subsequent commands USER node
Files to exclude from build context node_modules .git *.md
Multi-stage build for smaller images FROM node:20 AS builder RUN npm run build FROM nginx:alpine COPY --from=builder /app/dist /usr/share/nginx/html

Compose

Command Description Example
Start all services docker compose up -d
Stop and remove containers docker compose down -v (remove volumes)
Build/rebuild services docker compose build --no-cache
List compose services docker compose ps
View service logs docker compose logs -f api
Run command in service docker compose exec db psql -U postgres
Run one-off command docker compose run api npm test
Pull service images docker compose pull
Restart services docker compose restart api
Validate compose file docker compose config

Volumes & Networks

Command Description Example
Create named volume docker volume create db-data
List volumes docker volume ls
Remove volume docker volume rm db-data
Remove unused volumes docker volume prune -f
Create network docker network create mynet
List networks docker network ls
Connect container to network docker network connect mynet web
Show network details docker network inspect bridge

System

Command Description Example
Show disk usage docker system df -v
Remove all unused data docker system prune -a --volumes
Show system-wide information docker info
Show Docker version docker version
Log in to registry docker login -u username

Frequently asked questions

What's the difference between an image and a container?

An image is a read-only template with your app, dependencies, and OS. A container is a running instance of an image. Think of it like a class (image) vs object (container). You can run multiple containers from one image.

What's the difference between CMD and ENTRYPOINT?

CMD sets the default command that can be overridden at runtime: docker run myapp bash replaces CMD. ENTRYPOINT sets a fixed command - runtime args are appended: ENTRYPOINT ["node"] with docker run myapp server.js runs 'node server.js'. Use ENTRYPOINT for the executable, CMD for default arguments.

How do I reduce Docker image size?

1) Use alpine base images (node:20-alpine). 2) Multi-stage builds (build in full image, copy to slim image). 3) Combine RUN commands to reduce layers. 4) Use .dockerignore. 5) Don't install dev dependencies in production. 6) Clean up package manager cache in the same RUN layer.

How do containers communicate with each other?

Containers on the same Docker network can reach each other by container name (or Compose service name) as hostname. Create a network with 'docker network create mynet' or use Compose (automatic). Container-to-container uses internal ports, not mapped host ports.

What's the difference between volumes and bind mounts?

Volumes are managed by Docker (docker volume create) - good for persistent data like databases. Bind mounts map a host directory into the container (-v ./src:/app/src) - good for development with hot reload. Volumes are more portable and performant.

How do I pass secrets to containers?

Never bake secrets into images (ENV in Dockerfile). Use --env-file .env at runtime, Docker secrets (Swarm), or your orchestrator's secret management. In Compose, use env_file: .env. For CI/CD, inject secrets as environment variables at deploy time.

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