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Posted on Sep 20

Docker Cheatsheet: Quick Reference for Developers

Introduction
Docker is a containerization platform that allows you to package applications and their dependencies into lightweight, portable containers. Here’s a quick cheatsheet to get started and work efficiently with Docker.

1. Docker Basics

Check Docker version:

docker --version

List running containers:

docker ps

List all containers (running + stopped):

docker ps -a

List all images:

docker images

Stop a container:

docker stop <container_id>

Remove a container:

docker rm <container_id>

Remove an image:

docker rmi <image_name>

2. Working with Images

Pull an image from Docker Hub:

docker pull <image_name>:<tag>

Build an image from Dockerfile:

docker build -t <image_name>:<tag> .

Run a container from an image:

docker run -d --name <container_name> <image_name>:<tag>

Run container with port mapping:

docker run -d -p 8080:80 <image_name>

3. Dockerfile Essentials

Basic structure:

# Use a base image
FROM node:18

# Set working directory
WORKDIR /app

# Copy package files and install dependencies
COPY package*.json ./
RUN npm install

# Copy app source code
COPY . .

# Expose port and start app
EXPOSE 3000
CMD ["node", "index.js"]

4. Docker Compose Basics

docker-compose.yml example for Node.js + MongoDB:

version: '3'
services:
  app:
    build: .
    ports:
      - "3000:3000"
    volumes:
      - .:/app
    depends_on:
      - mongo

  mongo:
    image: mongo:6
    ports:
      - "27017:27017"

Commands:

docker-compose up        # Start all services
docker-compose down      # Stop all services
docker-compose logs -f   # Follow logs

5. Useful Docker Commands

View container logs:

docker logs -f <container_id>

Execute a command in running container:

docker exec -it <container_id> bash

Remove all stopped containers:

docker container prune

Remove unused images:

docker image prune -a

Conclusion:
Docker simplifies deployment, ensures consistency, and makes scaling easier. Keep this cheatsheet handy while developing and experimenting with containers.

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