## 📝 Author

Birat Aryal — birataryal.github.io
Created Date: 2025-06-18
Updated Date: Wednesday 18th June 2025 10:54:39
Website - birataryal.com.np
Repository - Birat Aryal
LinkedIn - Birat Aryal
DevSecOps Engineer | System Engineer | Cyber Security Analyst | Network Engineer

📦 Docker Compose Examples and Use Cases

Docker Compose is a tool for defining and running multi-container Docker applications. It allows you to configure services, networks, and volumes in a single docker-compose.yml file.

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🧰 Basic Usage

Sample docker-compose.yml

YAML

version: '3.8'
services:
  web:
    image: nginx:latest
    ports:
      - "8080:80"

  app:
    build: ./app
    volumes:
      - ./app:/usr/src/app
    environment:
      - NODE_ENV=development
    depends_on:
      - db

  db:
    image: postgres:13
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: pass
      POSTGRES_DB: mydb
    volumes:
      - pgdata:/var/lib/postgresql/data

volumes:
  pgdata:

Commands

Bash

docker-compose up         # Start all services
docker-compose down       # Stop and remove containers, networks, volumes
docker-compose build      # Build all services defined in the file
docker-compose ps         # List running services
docker-compose logs -f    # View logs

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💡 Use Cases

1. Development Environments

• Run backend, frontend, and database containers together.

• Hot reload changes using volumes.

2. CI/CD Testing Pipelines

• Define disposable environments for integration tests.

• Reproducible setups using same Compose config in test pipelines.

3. Service Dependencies

• Automatically manage dependencies (e.g., depends_on).

• Use health checks to ensure readiness.

4. Local Replication of Production

• Simulate production stack locally using the same Compose setup.

5. Database Migrations

• Add migration containers with custom entrypoints to perform migrations at startup.

6. Multi-network Applications

• Define multiple networks to isolate internal services from public-facing ones.

---

🛠 Advanced Features

Profiles (v3.9+)

YAML

services:
  debug:
    image: alpine
    command: sleep infinity
    profiles: ["debug"]

Bash

docker-compose --profile debug up

Override Configuration

Bash

docker-compose -f docker-compose.yml -f docker-compose.override.yml up

Resource Limits

YAML

services:
  app:
    deploy:
      resources:
        limits:
          cpus: "0.5"
          memory: "512M"

---

🌐 Real-World Compose Template: Full Stack Example

YAML

version: '3.8'
services:
  frontend:
    build: ./frontend
    ports:
      - "3000:3000"
    depends_on:
      - backend

  backend:
    build: ./backend
    ports:
      - "5000:5000"
    environment:
      - DATABASE_URL=postgres://user:pass@db:5432/mydb
    depends_on:
      - db

  db:
    image: postgres:14
    restart: always
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: pass
      POSTGRES_DB: mydb
    volumes:
      - db_data:/var/lib/postgresql/data

volumes:
  db_data:

---

🚀 Production Deployment Strategies

1. Use .env File for Configuration

Text Only

POSTGRES_USER=user
POSTGRES_PASSWORD=securepassword

YAML

environment:
  - POSTGRES_USER=${POSTGRES_USER}
  - POSTGRES_PASSWORD=${POSTGRES_PASSWORD}

Run with:

Bash

docker-compose --env-file .env up

2. Secrets Management

Use Docker Swarm or external secret managers for secure handling.

YAML

secrets:
  db_password:
    file: ./secrets/db_password.txt

services:
  db:
    secrets:
      - db_password

3. Restart Policies

Ensure services restart on failure or reboot:

YAML

restart: unless-stopped

Options:

• no

• always

• on-failure

• unless-stopped

4. Health Checks

Ensure containers are ready before serving traffic:

YAML

healthcheck:
  test: ["CMD", "curl", "-f", "http://localhost:80"]
  interval: 30s
  timeout: 10s
  retries: 3

5. Separate Production Overrides

Use a separate override file for prod-specific config:

Bash

docker-compose -f docker-compose.yml -f docker-compose.prod.yml up -d

6. Use Volumes for Persistent Data

Avoid using bind mounts for databases or production data.

YAML

volumes:
  db_data:
    driver: local

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