Docker từ Cơ bản đến Nâng cao

Phần 2: Dockerfile và Image Optimization

xdev.asia

1. Docker Compose là gì?

Docker Compose là tool cho phép định nghĩa và chạy multi-container applications bằng một file YAML duy nhất. Thay vì chạy nhiều lệnh docker run, bạn chỉ cần docker compose up.

Tại sao cần Docker Compose?

• Ứng dụng thực tế có nhiều services: web, database, cache, queue, ...

• Quản lý dependencies giữa các services

• Reproducible environments cho development và testing

• Infrastructure as Code - mọi thứ trong version control

2. Cú pháp docker-compose.yml

2.1. Cấu trúc cơ bản

# docker-compose.yml
services:
  web:
    image: nginx:1.27-alpine
    ports:
      - "80:80"
    volumes:
      - ./html:/usr/share/nginx/html:ro
    depends_on:
      - api
api:
build: ./backend
ports:
- "3000:3000"
environment:
- NODE_ENV=development
- DB_HOST=db
depends_on:
db:
condition: service_healthy
db:
image: postgres:16-alpine
environment:
POSTGRES_DB: myapp
POSTGRES_USER: admin
POSTGRES_PASSWORD: secretpassword
volumes:
- db-data:/var/lib/postgresql/data
healthcheck:
test: ["CMD-SHELL", "pg_isready -U admin -d myapp"]
interval: 10s
timeout: 5s
retries: 5
volumes:
db-data:
networks:
default:
driver: bridge

2.2. Services

services:
  # Sử dụng image có sẵn
  redis:
    image: redis:7-alpine
    ports:
      - "6379:6379"
Build từ Dockerfile
app:
build:
context: .
dockerfile: Dockerfile
args:
NODE_ENV: production
image: myapp:latest  # Tag cho built image

2.3. Ports

services:
  web:
    ports:
      - "80:80"          # host:container
      - "443:443"
      - "3000:3000"
      - "127.0.0.1:8080:80"  # Bind chỉ localhost

2.4. Volumes

services:
  db:
    volumes:
      - db-data:/var/lib/postgresql/data     # Named volume
      - ./init.sql:/docker-entrypoint-initdb.d/init.sql:ro  # Bind mount
      - /tmp/logs:/var/log                    # Host path
volumes:
db-data:
driver: local

2.5. Environment Variables

services:
  app:
    # Inline
    environment:
      - NODE_ENV=production
      - DB_HOST=db
      - DB_PORT=5432
# Hoặc dùng map syntax
environment:
  NODE_ENV: production
  DB_HOST: db

# Từ .env file
env_file:
  - .env
  - .env.local

2.6. depends_on và Healthcheck

services:
  app:
    depends_on:
      db:
        condition: service_healthy    # Đợi db healthy
      redis:
        condition: service_started    # Đợi redis bắt đầu
db:
image: postgres:16-alpine
healthcheck:
test: ["CMD-SHELL", "pg_isready -U postgres"]
interval: 10s
timeout: 5s
retries: 5
start_period: 30s
redis:
image: redis:7-alpine
healthcheck:
test: ["CMD", "redis-cli", "ping"]
interval: 10s
timeout: 5s
retries: 3

2.7. Networks

services:
  frontend:
    networks:
      - frontend-net
api:
networks:
- frontend-net
- backend-net
db:
networks:
- backend-net
networks:
frontend-net:
backend-net:

3. Docker Compose CLI

# Khởi động tất cả services
docker compose up
Khởi động ở background
docker compose up -d
Build và khởi động
docker compose up -d --build
Dừng tất cả services
docker compose down
Dừng và xóa volumes
docker compose down -v
Xem trạng thái services
docker compose ps
Xem logs
docker compose logs
docker compose logs -f api     # Follow logs của service cụ thể
Exec vào service
docker compose exec api sh
docker compose exec db psql -U admin -d myapp
Run one-off command
docker compose run --rm api npm test
Scale service
docker compose up -d --scale api=3
Restart service
docker compose restart api
Build/rebuild images
docker compose build
docker compose build --no-cache api

4. Lab: Deploy Full-stack Application

Triển khai ứng dụng với Nginx + Node.js API + PostgreSQL + Redis:

# docker-compose.yml
services:
  # Nginx Reverse Proxy
  nginx:
    image: nginx:1.27-alpine
    ports:
      - "80:80"
    volumes:
      - ./nginx/default.conf:/etc/nginx/conf.d/default.conf:ro
    depends_on:
      api:
        condition: service_healthy
    restart: unless-stopped

  # Node.js API
  api:
    build:
      context: ./backend
      dockerfile: Dockerfile
    environment:
      NODE_ENV: production
      DB_HOST: db
      DB_PORT: 5432
      DB_NAME: myapp
      DB_USER: admin
      DB_PASSWORD: secretpassword
      REDIS_URL: redis://redis:6379
    depends_on:
      db:
        condition: service_healthy
      redis:
        condition: service_healthy
    healthcheck:
      test: ["CMD", "wget", "--spider", "-q", "http://localhost:3000/health"]
      interval: 15s
      timeout: 5s
      retries: 3
    restart: unless-stopped

  # PostgreSQL Database
  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_DB: myapp
      POSTGRES_USER: admin
      POSTGRES_PASSWORD: secretpassword
    volumes:
      - postgres-data:/var/lib/postgresql/data
      - ./db/init.sql:/docker-entrypoint-initdb.d/init.sql:ro
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U admin -d myapp"]
      interval: 10s
      timeout: 5s
      retries: 5
    restart: unless-stopped

  # Redis Cache
  redis:
    image: redis:7-alpine
    command: redis-server --appendonly yes --maxmemory 256mb --maxmemory-policy allkeys-lru
    volumes:
      - redis-data:/data
    healthcheck:
      test: ["CMD", "redis-cli", "ping"]
      interval: 10s
      timeout: 5s
      retries: 3
    restart: unless-stopped

volumes:
  postgres-data:
  redis-data:

# Deploy
docker compose up -d

# Kiểm tra
docker compose ps
docker compose logs -f

# Test
curl http://localhost/api/health

5. Tổng kết

Trong bài này, bạn đã nắm được:

• Docker Compose là gì và tại sao cần dùng

• Cú pháp docker-compose.yml: services, volumes, networks

• depends_on với healthcheck conditions

• Docker Compose CLI: up, down, ps, logs, exec

• Lab thực hành: Nginx + Node.js + PostgreSQL + Redis

Bài tiếp theo sẽ đi sâu vào Docker Networking - cách containers giao tiếp với nhau.