Docker Compose — Production — Practice Exercises

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Practice production-ready Docker Compose configurations.

Exercise 1: Restart Policy

Configure a web server to restart automatically unless manually stopped.

Solution 
services:
  web:
    image: nginx:alpine
    restart: unless-stopped
    ports:
      - "80:80"

Test: docker compose kill web → it auto-restarts.

Exercise 2: Resource Limits

Set CPU and memory limits on an API service.

Solution 
services:
  api:
    image: node:20-alpine
    command: node server.js
    deploy:
      resources:
        limits:
          cpus: "0.5"
          memory: 256M
        reservations:
          cpus: "0.1"
          memory: 64M

Verify: docker stats

Exercise 3: Log Rotation

Configure JSON file logging with rotation for all services.

Solution 
x-logging: &logging
  logging:
    driver: json-file
    options:
      max-size: "10m"
      max-file: "3"

services:
  api:
    <<: *logging
    image: myapi:latest
  db:
    <<: *logging
    image: postgres:16

Exercise 4: Scale a Service

Scale an API to 3 instances behind an Nginx load balancer.

Solution 
services:
  nginx:
    image: nginx:alpine
    ports:
      - "80:80"
    depends_on:
      - api

  api:
    image: myapi:latest
    deploy:
      replicas: 3
    expose:
      - "3000"

docker compose up -d
docker compose ps    # Shows 3 api instances

Exercise 5: CI/CD Test Pipeline

Write a compose file for running tests in CI with proper cleanup.

Solution 
services:
  db:
    image: postgres:16
    environment:
      POSTGRES_PASSWORD: test
    healthcheck:
      test: ["CMD-SHELL", "pg_isready"]
      interval: 5s
      retries: 5

  test:
    build: .
    command: npm test
    depends_on:
      db:
        condition: service_healthy
    environment:
      DATABASE_URL: postgres://postgres:test@db:5432/postgres

docker compose run --rm --exit-code-from test test
docker compose down -v

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