docker-compose.yml

services:
  # ── Data layer ──────────────────────────────────────
  postgres:
    image: postgres:16-alpine
    environment:
      POSTGRES_DB: ${POSTGRES_DB:-app_db}
      POSTGRES_USER: ${POSTGRES_USER:-app_user}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-app_password}
    volumes:
      - postgres_data:/var/lib/postgresql/data
      - ./database/init:/docker-entrypoint-initdb.d:ro
      - ./backups:/backups
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER:-app_user} -d ${POSTGRES_DB:-app_db}"]
      interval: 10s
      timeout: 5s
      retries: 5
      start_period: 10s
    restart: unless-stopped

  # ── Application replicas ────────────────────────────
  app1: &app-template
    build:
      context: ./app
    image: sna-flask-app:latest
    environment:
      APP_NAME: ${APP_NAME:-sna-demo-app}
      APP_INSTANCE_ID: app-1
      PORT: "8000"
      DATABASE_URL: postgresql://${POSTGRES_USER:-app_user}:${POSTGRES_PASSWORD:-app_password}@postgres:5432/${POSTGRES_DB:-app_db}
      DB_CONNECT_RETRIES: ${DB_CONNECT_RETRIES:-20}
      DB_CONNECT_DELAY: ${DB_CONNECT_DELAY:-2}
      DB_POOL_MAX_SIZE: ${DB_POOL_MAX_SIZE:-10}
    depends_on:
      postgres:
        condition: service_healthy
    expose:
      - "8000"
    healthcheck:
      test: ["CMD", "python", "-c", "import urllib.request; urllib.request.urlopen('http://127.0.0.1:8000/health', timeout=3).read()"]
      interval: 10s
      timeout: 5s
      retries: 3
      start_period: 15s
    restart: unless-stopped

  app2:
    <<: *app-template
    environment:
      APP_NAME: ${APP_NAME:-sna-demo-app}
      APP_INSTANCE_ID: app-2
      PORT: "8000"
      DATABASE_URL: postgresql://${POSTGRES_USER:-app_user}:${POSTGRES_PASSWORD:-app_password}@postgres:5432/${POSTGRES_DB:-app_db}
      DB_CONNECT_RETRIES: ${DB_CONNECT_RETRIES:-20}
      DB_CONNECT_DELAY: ${DB_CONNECT_DELAY:-2}
      DB_POOL_MAX_SIZE: ${DB_POOL_MAX_SIZE:-10}

  app3:
    <<: *app-template
    environment:
      APP_NAME: ${APP_NAME:-sna-demo-app}
      APP_INSTANCE_ID: app-3
      PORT: "8000"
      DATABASE_URL: postgresql://${POSTGRES_USER:-app_user}:${POSTGRES_PASSWORD:-app_password}@postgres:5432/${POSTGRES_DB:-app_db}
      DB_CONNECT_RETRIES: ${DB_CONNECT_RETRIES:-20}
      DB_CONNECT_DELAY: ${DB_CONNECT_DELAY:-2}
      DB_POOL_MAX_SIZE: ${DB_POOL_MAX_SIZE:-10}

  # ── Reverse proxy & exporter ────────────────────────
  nginx:
    image: nginx:1.27-alpine
    ports:
      - "${NGINX_HTTP_PORT:-80}:80"
    volumes:
      - ./nginx/nginx.conf:/etc/nginx/nginx.conf:ro
      # Mount the upstream and public vhost over the default image config so localhost
      # always hits the reverse proxy instead of NGINX's bundled welcome page.
      - ./nginx/upstreams/round-robin.conf:/etc/nginx/conf.d/upstream.conf:ro
      - ./nginx/conf.d/default.conf:/etc/nginx/conf.d/default.conf:ro
      - ./nginx/conf.d/metrics.conf:/etc/nginx/conf.d/metrics.conf:ro
    depends_on:
      app1:
        condition: service_healthy
      app2:
        condition: service_healthy
      app3:
        condition: service_healthy
    restart: unless-stopped

  nginx-exporter:
    image: nginx/nginx-prometheus-exporter:1.5.1
    command:
      - --nginx.scrape-uri=http://nginx:8080/stub_status
    expose:
      - "9113"
    ports:
      - "${NGINX_EXPORTER_PORT:-9113}:9113"
    depends_on:
      nginx:
        condition: service_started
    restart: unless-stopped

  node-exporter:
    image: prom/node-exporter:v1.8.1
    command:
      - '--path.rootfs=/host'
    volumes:
      - /:/host:ro
    expose:
      - "9100"
    restart: unless-stopped

  cadvisor:
    image: gcr.io/cadvisor/cadvisor:v0.49.1
    privileged: true
    volumes:
      - /:/rootfs:ro
      - /var/run/docker.sock:/var/run/docker.sock:ro
      - /var/run:/var/run:rw
      - /sys:/sys:ro
      - /var/lib/docker:/var/lib/docker:ro
    expose:
      - "8080"
    restart: unless-stopped

  # ── Monitoring (Member B) ───────────────────────────
  prometheus:
    image: prom/prometheus:v2.52.0
    container_name: prometheus
    volumes:
      - ./monitoring/prometheus/prometheus.yml:/etc/prometheus/prometheus.yml
      - prometheus_data:/prometheus
    command:
      - '--config.file=/etc/prometheus/prometheus.yml'
      - '--storage.tsdb.path=/prometheus'
      - '--web.console.libraries=/usr/share/prometheus/console_libraries'
      - '--web.console.templates=/usr/share/prometheus/consoles'
    ports:
      - "9090:9090"
    restart: unless-stopped

  grafana:
    image: grafana/grafana:11.0.0
    container_name: grafana
    volumes:
      - ./monitoring/grafana/datasources.yml:/etc/grafana/provisioning/datasources/datasources.yml
      - ./monitoring/grafana/dashboards.yml:/etc/grafana/provisioning/dashboards/dashboards.yml
      - ./monitoring/grafana/dashboards:/var/lib/grafana/dashboards:ro
      - grafana_data:/var/lib/grafana
    environment:
      GF_SECURITY_ADMIN_USER: admin
      GF_SECURITY_ADMIN_PASSWORD: admin
    ports:
      - "3000:3000"
    restart: unless-stopped

  loki:
    image: grafana/loki:3.0.0
    container_name: loki
    volumes:
      - ./monitoring/loki/local-config.yaml:/etc/loki/local-config.yaml
      - loki_data:/loki
    command: -config.file=/etc/loki/local-config.yaml
    ports:
      - "3100:3100"
    restart: unless-stopped

  promtail:
    image: grafana/promtail:3.0.0
    container_name: promtail
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - ./monitoring/promtail/config.yml:/etc/promtail/config.yml
    command: -config.file=/etc/promtail/config.yml
    restart: unless-stopped

  # ── Load testing (optional) ─────────────────────────
  loadtester:
    build:
      context: ./loadtest
    image: sna-loadtester:latest
    profiles:
      - loadtest          # Only starts with --profile loadtest
    environment:
      TARGET_URL: ${LOADTEST_TARGET_URL:-http://nginx}
      LOAD_DURATION: ${LOAD_DURATION:-120}
      LOAD_CONCURRENCY: ${LOAD_CONCURRENCY:-20}
      LOAD_INTERVAL: ${LOAD_INTERVAL:-0.05}
      LOAD_WRITE_RATIO: ${LOAD_WRITE_RATIO:-0.35}
      LOAD_TIMEOUT: ${LOAD_TIMEOUT:-5}
    depends_on:
      - nginx
    restart: "no"

volumes:
  postgres_data:
  prometheus_data:
  grafana_data:
  loki_data: