502 handling on discourse.conf

discourse.conf

upstream discourse {
  server unix:/home/discourse/discourse/tmp/sockets/thin.0.sock;
  server unix:/home/discourse/discourse/tmp/sockets/thin.1.sock;
  server unix:/home/discourse/discourse/tmp/sockets/thin.2.sock;
  server unix:/home/discourse/discourse/tmp/sockets/thin.3.sock;
}

server {

  listen 80;
  gzip on;
  gzip_min_length 1000;
  gzip_types application/json text/css application/x-javascript;

    error_page 502 /502.html;
    root   /usr/share/nginx/html;
    index  index.html index.htm;

  server_name enter.your.web.hostname.here;

  sendfile on;
  keepalive_timeout 65;
  client_max_body_size 2m;

  location / {
    root /home/discourse/discourse/public;

    ## optional upload anti-hotlinking rules
    #location ~ ^/uploads/ {
    #  valid_referers none blocked mysite.com *.mysite.com;
    #  if ($invalid_referer) {
    #    return 403;
    #  }
    #}

    location ~ ^/t\/[0-9]+\/[0-9]+\/avatar {
      expires 1d;
      add_header Cache-Control public;
      add_header ETag "";
    }

    location ~ ^/(assets|uploads)/ {
      expires 1y;
      add_header Cache-Control public;
      add_header ETag "";
      break;
    }

    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  Host $http_host;


    # If the file exists as a static file serve it directly without
    # running all the other rewrite tests on it
    if (-f $request_filename) {
      break;
    }

    if (!-f $request_filename) {
      proxy_pass http://discourse;
      break;
    }

  }
 
  location = /502.html {

  }



}