Complete Guide to Docker Commands

Docker commands are the backbone of container management. This guide covers essential commands, their use cases, and best practices. Bookmark this as your Docker CLI cheat sheet!

1. Installation & Setup

2. Core Docker Commands

Image Management

Command Description Example
docker pull Download an image from a registry docker pull nginx:latest
docker build Build an image from a Dockerfile docker build -t my-app:v1 .
docker images List all local images docker images
docker rmi Remove an image docker rmi my-app:v1
docker tag Tag an image docker tag my-app:v1 my-repo/my-app:prod
docker push Push an image to a registry docker push my-repo/my-app:prod

Container Management

Command Description Example
docker run Start a new container docker run -d -p 8080:80 --name web nginx
docker ps List running containers docker ps -a (show all containers)
docker start/stop Start/stop a container docker stop web
docker restart Restart a container docker restart web
docker rm Remove a stopped container docker rm web
docker exec Run a command in a running container docker exec -it web bash
docker logs View container logs docker logs -f web (follow logs)
docker inspect View container details docker inspect web
docker stats Monitor resource usage docker stats

Flags Explained

3. Dockerfile Basics

A Dockerfile defines how to build an image. Example:

# Use a base image
FROM python:3.9-slim

# Set working directory
WORKDIR /app

# Copy files
COPY requirements.txt .
COPY app.py .

# Install dependencies
RUN pip install -r requirements.txt

# Expose port
EXPOSE 5000

# Define startup command
CMD ["python", "app.py"]

Build the image:

docker build -t my-python-app:latest .

4. Docker Compose

Define multi-container apps in docker-compose.yml:

version: '3.8'
services:
  web:
    image: nginx:latest
    ports:
      - "80:80"
    volumes:
      - ./html:/usr/share/nginx/html
  db:
    image: postgres:14
    environment:
      POSTGRES_PASSWORD: mysecret

Key commands:

docker-compose up -d    # Start containers
docker-compose down     # Stop and remove containers
docker-compose logs     # View logs

5. Docker Networking

Command Description Example
docker network ls List networks docker network ls
docker network create Create a custom network docker network create my-net
docker network inspect Inspect a network docker network inspect my-net
docker run --network Attach a container to a network docker run --network=my-net my-app

6. Volumes & Persistence Data

Command Description Example
docker volume create Create a named volume docker volume create my-vol
docker run -v Mount a volume docker run -v my-vol:/data my-app
docker volume ls List volumes docker volume ls
docker volume inspect Inspect a volume docker volume inspect my-vol

7. Advanced Commands

Cleanup

docker system prune       # Remove unused images, containers, networks
docker volume prune       # Remove unused volumes

Swarm Mode (Orchestration)

docker swarm init         # Initialize a Swarm cluster
docker service create     # Deploy a service
docker stack deploy       # Deploy a stack from a Compose file

Image Inspection

docker history my-image   # Show image layer history
docker scan my-image      # Scan for vulnerabilities

8. Common Use Cases

  1. Run a Temporary Container

    docker run --rm -it ubuntu:22.04 bash

    The --rm flag deletes the container after it stops.

  2. Persist Database Data

    docker run -d --name mysql-db -v mysql_data:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=secret mysql:8

  3. Copy Files to/from a Container

    docker cp app.log web:/app/logs   # Host → Container
docker cp web:/app/logs ./logs    # Container → Host

  4. Debug a Container

    docker exec -it web sh            # Open a shell in the container
docker logs web --tail 100 -f     # Tail the last 100 logs

9. Best Practices

  1. Use .dockerignore
    Exclude unnecessary files (like node_modules) during builds.
  2. Minimize Image Layers
    Combine multiple RUN commands in the Dockerfile.
  3. Avoid latest Tags in Production
    Use specific versions (e.g., nginx:1.23.3).
  4. Run as Non-Root User
    Add USER appuser in your Dockerfile.
  5. Leverage Multi-Stage Builds
    Reduce image size by separating build and runtime stages.

10. Troubleshooting

Cheat Sheet Table

Category Command
Images docker pull, docker build, docker images, docker rmi
Containers docker run, docker ps, docker start/stop, docker exec, docker logs
Networking docker network create, docker network ls
Volumes docker volume create, docker run -v
Compose docker-compose up, docker-compose down

Learning Resources