Docker

TL;DR

What: Package apps into portable containers that run anywhere.

Why: “Works on my machine” → works everywhere.

Quick Start

Install:

macOS/Windows: Download Docker Desktop

Linux:

curl -fsSL https://get.docker.com | sh
sudo usermod -aG docker $USER

First container:

docker run hello-world

Cheatsheet

Command	Description
docker run IMAGE	Run a container
docker ps	List running containers
docker ps -a	List all containers
docker images	List images
docker pull IMAGE	Download an image
docker stop ID	Stop a container
docker rm ID	Remove a container
docker rmi IMAGE	Remove an image

Gotchas

Permission denied on Linux

sudo usermod -aG docker $USER
# Then logout and login again

Port already in use

docker run -p 3001:80 nginx  # Use different host port

Container stops immediately

docker run -it IMAGE bash  # Run interactively
docker logs CONTAINER_ID   # Check logs

Next Steps

• Dockerfile Guide
• Docker Compose
• Docker Hub