nginx/nginx.conf

worker_processes auto;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;

events {
    worker_connections 1024;
    use epoll;
    multi_accept on;
}

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

    log_format main '$remote_addr [$time_local] "$request" $status $body_bytes_sent rt=$request_time';
    access_log /var/log/nginx/access.log main;

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    client_max_body_size 20M;

    gzip on;
    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_types text/plain text/css application/json application/javascript
               application/xml text/xml application/atom+xml image/svg+xml;

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

    upstream backend  { server backend:8000;  keepalive 32; }
    upstream frontend { server frontend:3000; keepalive 16; }

    # ── HTTP → HTTPS redirect + ACME challenge ────────────────────────────────
    server {
        listen 80;
        server_name _;

        # Let's Encrypt ACME challenge
        location /.well-known/acme-challenge/ {
            root /var/www/certbot;
        }

        location / {
            return 301 https://$host$request_uri;
        }
    }

    # ── HTTPS ─────────────────────────────────────────────────────────────────
    server {
        listen 443 ssl http2;
        server_name _;

        ssl_certificate     /etc/letsencrypt/live/DOMAIN/fullchain.pem;
        ssl_certificate_key /etc/letsencrypt/live/DOMAIN/privkey.pem;
        ssl_protocols       TLSv1.2 TLSv1.3;
        ssl_ciphers         ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256;
        ssl_prefer_server_ciphers off;
        ssl_session_cache   shared:SSL:10m;
        ssl_session_timeout 1d;

        # Security headers
        add_header Strict-Transport-Security "max-age=63072000; includeSubDomains" always;
        add_header X-Frame-Options "SAMEORIGIN" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Referrer-Policy "strict-origin-when-cross-origin" always;

        # Health check — no rate limit
        location = /health {
            proxy_pass http://backend/health;
            proxy_set_header Host $host;
            access_log off;
        }

        # API → backend
        location /api/ {
            limit_req zone=api burst=20 nodelay;
            proxy_pass http://backend;
            proxy_http_version 1.1;
            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 https;
            proxy_set_header Connection "";
            proxy_read_timeout 120s;
            proxy_buffering off;
            proxy_cache off;
        }

        # File upload — stricter limit
        location ~ ^/api/(analyze|voice/transcribe) {
            limit_req zone=upload burst=5 nodelay;
            proxy_pass http://backend;
            proxy_http_version 1.1;
            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 https;
            proxy_set_header Connection "";
            client_max_body_size 20M;
            proxy_read_timeout 120s;
            proxy_buffering off;
        }

        # Next.js static assets — long cache
        location /_next/static/ {
            proxy_pass http://frontend;
            proxy_set_header Host $host;
            add_header Cache-Control "public, max-age=31536000, immutable";
            access_log off;
        }

        # Frontend
        location / {
            proxy_pass http://frontend;
            proxy_http_version 1.1;
            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 https;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
            proxy_read_timeout 60s;
        }
    }
}