Removes un-necessary shutdown handler (#3786)

* Removes un-necessary shutdown handler

- When registering a shutdown hander, the node process has to be exited manually which causes issues for many users

* Proper graceful shutdown from CLI

src/Adapters/Storage/Mongo/MongoStorageAdapter.js

@@ -97,17 +97,6 @@ export class MongoStorageAdapter {
 
     // MaxTimeMS is not a global MongoDB client option, it is applied per operation.
     this._maxTimeMS = mongoOptions.maxTimeMS;
-    process.on('SIGTERM', this.handleShutdown(this));
-    process.on('SIGINT', this.handleShutdown(this));
-  }
-
-  handleShutdown(storageAdapter) {
-    return () => {
-      if (!storageAdapter.database) {
-        return;
-      }
-      storageAdapter.database.close(false);
-    }
   }
 
   connect() {
@@ -139,6 +128,13 @@ export class MongoStorageAdapter {
     return this.connectionPromise;
   }
 
+  handleShutdown() {
+    if (!this.database) {
+      return;
+    }
+    this.database.close(false);
+  }
+
   _adaptiveCollection(name: string) {
     return this.connect()
       .then(() => this.database.collection(this._collectionPrefix + name))

src/ParseServer.js

@@ -313,6 +313,13 @@ class ParseServer {
     return ParseServer.app(this.config);
   }
 
+  handleShutdown() {
+    const { adapter } = this.config.databaseController;
+    if (adapter && typeof adapter.handleShutdown === 'function') {
+      adapter.handleShutdown();
+    }
+  }
+
   static app({maxUploadSize = '20mb', appId}) {
     // This app serves the Parse API directly.
     // It's the equivalent of https://api.parse.com/1 in the hosted Parse API.

src/cli/parse-server.js

@@ -1,6 +1,6 @@
 /* eslint-disable no-console */
 import express from 'express';
-import { ParseServer } from '../index';
+import ParseServer from '../index';
 import definitions from './definitions/parse-server';
 import cluster from 'cluster';
 import os from 'os';
@@ -43,9 +43,9 @@ function startServer(options, callback) {
     app.use(middleware);
   }
 
-  const api = new ParseServer(options);
+  const parseServer = new ParseServer(options);
   const sockets = {};
-  app.use(options.mountPath, api);
+  app.use(options.mountPath, parseServer.app);
 
   const server = app.listen(options.port, options.host, callback);
   server.on('connection', initializeConnections);
@@ -85,6 +85,7 @@ function startServer(options, callback) {
     console.log('Termination signal received. Shutting down.');
     destroyAliveConnections();
     server.close();
+    parseServer.handleShutdown();
   };
   process.on('SIGTERM', handleShutdown);
   process.on('SIGINT', handleShutdown);