Welcome to LeviFREE's Blog

What is Docker?#

Docker is a platform that lets you package applications into containers — standardized units that include everything needed to run the software: code, runtime, libraries, and system tools.

Think of it as a lightweight virtual machine, but way faster and more efficient.

Your First Dockerfile#

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

Building and Running#

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# Build the image
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docker build -t my-app .
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# Run a container
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docker run -d -p 3000:3000 --name my-app my-app
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# Check running containers
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docker ps
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# View logs
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docker logs my-app

Docker Compose for Multi-Service Apps#

When your app depends on multiple services (database, cache, etc.), docker-compose.yml makes orchestration simple:

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services:
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  web:
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    build: .
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    ports:
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      - "3000:3000"
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    depends_on:
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      - db
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      - redis
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  db:
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    image: postgres:16-alpine
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    environment:
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      POSTGRES_DB: myapp
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      POSTGRES_PASSWORD: secret
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    volumes:
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      - pgdata:/var/lib/postgresql/data
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  redis:
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    image: redis:7-alpine
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volumes:
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  pgdata:

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docker compose up -d

Best Practices#

1. Use multi-stage builds to reduce image size
2. Don’t run as root — add a non-root user
3. Use .dockerignore to exclude unnecessary files
4. Pin versions — avoid latest tags in production
5. Leverage layer caching — order commands from least to most frequently changing

Docker fundamentally changed how we think about deployment. Once you containerize your app, it runs the same everywhere — your laptop, CI/CD pipeline, or production server.