Docker Guide

Check if Docker is installed

Run this in your terminal. If you see a version number, Docker is installed.

docker --version

Install Docker (Linux)

Official one-liner from get.docker.com. Works on Ubuntu, Debian, CentOS, Fedora.

curl -fsSL https://get.docker.com -o get-docker.sh && sudo sh get-docker.sh

After install, add your user to the docker group to run without sudo:

sudo usermod -aG docker $USER && newgrp docker

Install Docker (macOS / Windows)

Install Docker Desktop — it includes Docker Engine, Docker Compose, and a GUI.

• → macOS (Apple Silicon & Intel)
• → Windows (WSL2 required)

Run your first container

Pull and run the hello-world image to verify Docker works.

docker run hello-world

Run an interactive Ubuntu container:

docker run -it ubuntu bash

Docker Images

Images are read-only templates for containers. Pull from Docker Hub:

docker pull nginx:alpine

docker images

docker rmi nginx:alpine

Building Images with Dockerfile

A Dockerfile defines how to build your image. Create a file named Dockerfile:

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

Build and tag the image:

docker build -t my-app:latest .

Volumes

Volumes persist data beyond container lifecycle.

docker volume create my-data

docker run -v my-data:/app/data nginx

docker run -v $(pwd)/src:/app/src nginx

Networking

Containers communicate through Docker networks.

docker network create my-net

docker run --network my-net --name web nginx

docker network ls

Useful Commands Cheat Sheet

docker ps

docker ps -a

docker logs -f <container>

docker exec -it <container> sh

docker stop <container>

docker rm <container>

docker system prune -af