Resolve intermittent premature connection closed (#19808)

Node 8 changed the keepAlive to default to 5 seconds from 5 minutes. This reverts that behavior.

Signed-off-by: Tyler Smalley <tyler.smalley@elastic.co>

src/server/http/setup_connection.js

@@ -28,7 +28,11 @@ export function setupConnection(server, config) {
 
   // not using https? well that's easy!
   if (!useSsl) {
-    server.connection(connectionOptions);
+    const connection = server.connection(connectionOptions);
+
+    // revert to previous 5m keepalive timeout in Node < 8
+    connection.listener.keepAliveTimeout = 120e3;
+
     return;
   }
 
@@ -47,6 +51,9 @@ export function setupConnection(server, config) {
     }
   });
 
+  // revert to previous 5m keepalive timeout in Node < 8
+  connection.listener.keepAliveTimeout = 120e3;
+
   const badRequestResponse = new Buffer('HTTP/1.1 400 Bad Request\r\n\r\n', 'ascii');
   connection.listener.on('clientError', (err, socket) => {
     if (socket.writable) {