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

events {
    worker_connections 1024;
}

http {
    include       /etc/nginx/mime.types;
    default_type  text/html;
    sendfile      on;
    server_tokens off;
    charset       utf-8;

    map $http_upgrade $connection_upgrade {
        default upgrade;
        ""      close;
    }

    map $status $error_title {
        default "Service Unavailable";
        502     "Bad Gateway";
        503     "Service Unavailable";
        504     "Gateway Timeout";
    }

    include /etc/nginx/upstreams.map;

    server {
        listen 127.0.0.1:4098;
        server_name _;

        root /usr/share/nginx/html;
        absolute_redirect off;

        location = /healthz {
            access_log off;
            default_type text/plain;
            return 200 "ok\n";
        }

        error_page 502 503 504 /__error/index.html;

        location = /__error/index.html {
            internal;
            sub_filter_once off;
            sub_filter_types text/html;
            sub_filter "__STATUS__" $status;
            sub_filter "__ERROR_TITLE__" $error_title;
            sub_filter "__HOST__" $host;
            add_header Cache-Control "no-store" always;
            add_header X-Content-Type-Options "nosniff" always;
        }

        location / {
            if ($app_port = 0) {
                return 502;
            }

            proxy_pass http://127.0.0.1:$app_port;
            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 $scheme;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection $connection_upgrade;

            proxy_connect_timeout 3s;
            proxy_send_timeout 3600s;
            proxy_read_timeout 3600s;

            # Only replace DSM-style "upstream down" pages. App 404/500 stay as-is.
            proxy_intercept_errors on;
        }
    }
}