Add /health HTTP endpoint

src/discordas.ts

@@ -176,6 +176,11 @@ async function run() {
     const roomhandler = discordbot.RoomHandler;
     const eventProcessor = discordbot.MxEventProcessor;
 
+    // tslint:disable-next-line:no-any
+    appservice.expressAppInstance.get("/health", (_, res: any) => {
+        res.status(201).send("");
+    });
+
     // tslint:disable-next-line:no-any
     appservice.on("query.room", async (roomAlias: string, createRoom: (opts: any) => Promise<void>) => {
         try {