nginx.conf

events {
    worker_connections 1024;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    # Logging
    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
                    '$status $body_bytes_sent "$http_referer" '
                    '"$http_user_agent" "$http_x_forwarded_for" '
                    'rt=$request_time uct="$upstream_connect_time" '
                    'uht="$upstream_header_time" urt="$upstream_response_time"';

    access_log /var/log/nginx/access.log main;
    error_log /var/log/nginx/error.log warn;

    # Performance optimizations
    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;
    client_max_body_size 10M;

    # Gzip compression
    gzip on;
    gzip_vary on;
    gzip_min_length 1024;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_types
        text/plain
        text/css
        text/xml
        text/javascript
        application/json
        application/javascript
        application/xml+rss
        application/atom+xml
        image/svg+xml;

    # Rate limiting
    limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;
    limit_req_zone $binary_remote_addr zone=general:10m rate=30r/s;

    # Upstream backend servers
    upstream backend {
        server backend:8000 max_fails=3 fail_timeout=30s;
        keepalive 32;
    }

    # Main server block
    server {
        listen 80;
        server_name localhost;

        # Security headers
        add_header X-Frame-Options "SAMEORIGIN" always;
        add_header X-XSS-Protection "1; mode=block" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Referrer-Policy "no-referrer-when-downgrade" always;
        add_header Content-Security-Policy "default-src 'self' http: https: data: blob: 'unsafe-inline'" always;

        # Health check endpoint (no rate limiting)
        location /health {
            proxy_pass http://backend/health;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_connect_timeout 5s;
            proxy_send_timeout 5s;
            proxy_read_timeout 5s;
            access_log off;
        }

        # Readiness check endpoint
        location /ready {
            proxy_pass http://backend/ready;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_connect_timeout 5s;
            proxy_send_timeout 5s;
            proxy_read_timeout 5s;
            access_log off;
        }

        # Metrics endpoint (restricted access)
        location /metrics {
            # Allow only internal networks
            allow 10.0.0.0/8;
            allow 172.16.0.0/12;
            allow 192.168.0.0/16;
            deny all;
            
            proxy_pass http://backend/metrics;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
        }

        # API endpoints with rate limiting
        location /api/ {
            limit_req zone=api burst=20 nodelay;
            
            proxy_pass http://backend/api/;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            
            # Timeouts
            proxy_connect_timeout 30s;
            proxy_send_timeout 30s;
            proxy_read_timeout 30s;
            
            # Buffer settings
            proxy_buffering on;
            proxy_buffer_size 4k;
            proxy_buffers 8 4k;
            
            # CORS headers for API
            add_header Access-Control-Allow-Origin "*" always;
            add_header Access-Control-Allow-Methods "GET, POST, OPTIONS" always;
            add_header Access-Control-Allow-Headers "DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range" always;
            add_header Access-Control-Expose-Headers "Content-Length,Content-Range" always;
            
            # Handle preflight requests
            if ($request_method = 'OPTIONS') {
                add_header Access-Control-Allow-Origin "*";
                add_header Access-Control-Allow-Methods "GET, POST, OPTIONS";
                add_header Access-Control-Allow-Headers "DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range";
                add_header Access-Control-Max-Age 1728000;
                add_header Content-Type "text/plain; charset=utf-8";
                add_header Content-Length 0;
                return 204;
            }
        }

        # Frontend static files
        location / {
            limit_req zone=general burst=50 nodelay;
            
            root /usr/share/nginx/html;
            index index.html;
            try_files $uri $uri/ /index.html;
            
            # Cache static assets
            location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
                expires 1y;
                add_header Cache-Control "public, immutable";
                try_files $uri =404;
            }
            
            # Cache HTML files for shorter time
            location ~* \.(html)$ {
                expires 1h;
                add_header Cache-Control "public, must-revalidate";
            }
        }

        # Error pages
        error_page 404 /404.html;
        error_page 500 502 503 504 /50x.html;
        
        location = /50x.html {
            root /usr/share/nginx/html;
        }
    }

    # HTTPS server (uncomment and configure for production)
    # server {
    #     listen 443 ssl http2;
    #     server_name yourdomain.com;
    #     
    #     ssl_certificate /etc/nginx/ssl/cert.pem;
    #     ssl_certificate_key /etc/nginx/ssl/key.pem;
    #     
    #     # SSL configuration
    #     ssl_protocols TLSv1.2 TLSv1.3;
    #     ssl_ciphers ECDHE-RSA-AES256-GCM-SHA512:DHE-RSA-AES256-GCM-SHA512:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384;
    #     ssl_prefer_server_ciphers off;
    #     ssl_session_cache shared:SSL:10m;
    #     ssl_session_timeout 10m;
    #     
    #     # HSTS
    #     add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
    #     
    #     # Include the same location blocks as above
    # }
}