Docker Containerization Guide

Docker packages applications and dependencies into containers for consistent deployment.

What is Docker?

Docker is a containerization platform that ensures applications run the same everywhere.

Images vs Containers

• Images: Templates used to create containers
• Containers: Running instances of images

Dockerfile

Create a Dockerfile to define your image:

FROM node:18
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD ["npm", "start"]

Docker Commands

docker build -t myapp .    # Build image
docker run myapp            # Run container
docker ps                   # List containers
docker stop <container>     # Stop container

Docker Compose

Manage multiple containers:

version: '3'
services:
  app:
    build: .
    ports:
      - "3000:3000"
  db:
    image: postgres

Benefits

• Consistency across environments
• Isolation and security
• Easy scaling and deployment