303 — Advanced Docker Compose Patterns

Master advanced Compose techniques: override files, extends, profiles, secrets, and production-ready patterns for complex multi-container applications.

Learning Objectives

Use multiple compose files and overrides

Implement extends and anchors for DRY configuration

Manage secrets and sensitive data

Use profiles for different environments

Apply production-ready compose patterns

Step 1

Multiple compose files and overrides

Combine base configuration with environment-specific overrides.

Commands to Run

mkdir compose-advanced && cd compose-advanced

cat > docker-compose.yml << 'EOF'
version: '3.8'

services:
  web:
    image: nginx:alpine
    ports:
      - "80:80"
  
  db:
    image: postgres:alpine
    environment:
      POSTGRES_PASSWORD: changeme
EOF

cat > docker-compose.override.yml << 'EOF'
version: '3.8'

services:
  web:
    ports:
      - "8080:80"
    volumes:
      - ./html:/usr/share/nginx/html
  
  db:
    ports:
      - "5432:5432"
EOF

docker compose config

What This Does

Compose automatically merges docker-compose.yml with docker-compose.override.yml. Use base file for shared config, override for local development.

Expected Outcome

'docker compose config' shows the merged configuration. Web port changes to 8080, volume is added, db port is exposed.

Pro Tips

1
docker-compose.override.yml is loaded automatically
2
Override file adds or replaces configuration
3
Don't commit override.yml - it's for local dev
4
Use for local ports, volumes, and debug settings
5
Arrays (ports, volumes) are merged, not replaced