If upstream is down let nginx show something positive

nginx.sites-enabled.default

upstream tomcat_servers{
    server 127.0.0.1:8080;# down;
    server 127.0.0.1:8181;# down;

    keepalive 128;
}

server {
        gzip on;
        gzip_comp_level 4;
        listen      80;
        underscores_in_headers on;


        location / {
        proxy_pass         http://tomcat_servers/;
        client_max_body_size       10m;
        client_body_buffer_size    128k;
        proxy_set_header From $remote_addr;

        proxy_buffering off;
        proxy_max_temp_file_size 0;
        proxy_connect_timeout      1200;
        proxy_send_timeout         1200;
        proxy_read_timeout         1200;
        proxy_buffer_size          8k;
        proxy_buffers              16 32k;
        proxy_busy_buffers_size    64k;
        proxy_temp_file_write_size 64k;
        set_real_ip_from 192.168.240.117;
        real_ip_header X-Real-IP;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;

        error_page 404 = @m404;
        error_page 500 502 503 504 = @m500;
        }

        location @m404 {
                root /opt/focus-it.ru/error-pages;
                internal;
            		proxy_intercept_errors on;
		            rewrite ^ /maintance_404.html;
		            break;
        }

        location @m500 {
                root /opt/focus-it.ru/error-pages;
                internal;
            		proxy_intercept_errors on;
            		rewrite ^ /maintance_50x.html;
            		break;
        }
}