title: Nginx internal dns resolve issue
body: <p>I have nginx container in AWS that does reverse proxy for my website e.g. <a href="https://example.com" rel="nofollow noreferrer">https://example.com</a>. I have backend services that automatically register in local DNS - aws.local (this is done by AWS ECS Auto-Discovery).
  The problem I have is that nginx is only resolving name to IP during start, so when service container is rebooted and gets new IP, nginx still tries old IP and I have "502 Bad Gateway" error.</p>
  
  <p>Here is a code that I am running:</p>
  
  <pre><code>worker_processes 1;
  events { worker_connections 1024; }
  http {
      sendfile on;
      include    /etc/nginx/mime.types;
      log_format  graylog2_json  '{ "timestamp": "$time_iso8601", '
                         '"remote_addr": "$remote_addr", '
                         '"body_bytes_sent": $body_bytes_sent, '
                         '"request_time": $request_time, '
                         '"response_status": $status, '
                         '"request": "$request", '
                         '"request_method": "$request_method", '
                         '"host": "$host",'
                         '"upstream_cache_status": "$upstream_cache_status",'
                         '"upstream_addr": "$upstream_addr",'
                         '"http_x_forwarded_for": "$http_x_forwarded_for",'
                         '"http_referrer": "$http_referer", '
                         '"http_user_agent": "$http_user_agent" }';
  
  
      upstream service1 {
          server service1.aws.local:8070;
      }
  
      upstream service2 {
          server service2.aws.local:8080;
      }
  
      resolver 10.0.0.2 valid=10s;
  
      server {
          listen 443 http2 ssl;
          server_name example.com;
          location /main {
              proxy_pass         http://service1;
          }
  
          location /auth {
              proxy_pass         http://service2;
          }
  </code></pre>
  
  <p>I find advices to change nginx config to resolve names per request, but then I see my browser tries to open "service2.aws.local:8070" and fails since its AWS local DNS name. I should see <a href="https://example.com/auth" rel="nofollow noreferrer">https://example.com/auth</a>" on my browser.</p>
  
  <pre><code>server {
  
          set $main service1.aws.local:2000;
          set $auth service2.aws.local:8070;
  
          location /main {
              proxy_http_version 1.1;
              proxy_pass http://$main;
          }
          location /auth {
              proxy_http_version 1.1;
              proxy_pass http://$auth;
          }
  </code></pre>
  
  <p>Can you help me fixing it? 
  Thanks !!!</p>