Configure Etherpad reverse proxy

As per:
https://github.com/ether/etherpad-lite/wiki/How-to-put-Etherpad-Lite-behind-a-reverse-Proxy

profile/manifests/etherpad/webserver.pp

@@ -21,10 +21,28 @@ class profile::etherpad::webserver {
     www_root             => '/var/lib/etherpad',
   }
 
+  nginx::resource::map { 'connection_upgrade':
+    default  => 'upgrade',
+    string   => '$http_upgrade',
+    mappings => {'\'\'' => 'close'},
+  }
+
   nginx::resource::location { 'etherpad-lite':
     server             => 'etherpad-lite',
     location           => '/',
-    proxy =>  'http://127.0.0.1:9001/'
+    proxy              => 'http://127.0.0.1:9001/',
+    proxy_buffering    => 'off',
+    proxy_http_version => '1.1',
+    proxy_pass_header  => ['Server'],
+    proxy_set_header   => [
+      'Host $host',
+      'X-Real-IP $remote_addr',
+      'X-Forwarded-For $proxy_add_x_forwarded_for',
+      'X-Forwarded-Host $host',
+      'X-Forwarded-Proto $scheme',
+      'Upgrade $http_upgrade',
+      'Connection $connection_upgrade',
+    ],
   }
 
   nginx::resource::location { 'etherpad-lite-index':