add metrics to notify route

packages/doorman-api/src/functions/api/door/notify.ts

@@ -1,6 +1,9 @@
 import { ServerlessEventObject, ServerlessFunctionSignature } from "@twilio-labs/serverless-runtime-types/types";
 import { TwilioContext } from "../../../types/TwilioContext";
 import { jsonMsgSuffix, sendMessageToUser } from "../../../utils/discord";
+import { getMetricFromRegistry, withMetrics } from "../../../common/DoormanHandler";
+import { NotifyMetrics, registerMetrics } from "../../../metrics/NotifyMetrics";
+import { Counter, Summary } from "prom-client";
 
 
 export interface NotifyRequest extends ServerlessEventObject {
@@ -12,9 +15,11 @@ export interface NotifyRequest extends ServerlessEventObject {
   json: string;
 }
 
-export const handler: ServerlessFunctionSignature<TwilioContext, NotifyRequest> = async function(context, event, callback) {
+export const handler: ServerlessFunctionSignature<TwilioContext, NotifyRequest> = withMetrics('notify', async (context, event, callback, metricsRegistry) => {
   const response = new Twilio.Response();
 
+  registerMetrics(metricsRegistry);
+
   let users: string[];
   let msgs: string[];
   let jsons: string[];
@@ -27,12 +32,22 @@ export const handler: ServerlessFunctionSignature<TwilioContext, NotifyRequest>
     jsons = JSON.parse(event.json);
     console.log("after parsing", event.json);
 
+    const recordNotifyLatency = getMetricFromRegistry<Summary>(metricsRegistry, NotifyMetrics.DISCORD_LATENCY)
+        .startTimer();
+
     promises = msgs.map((msg, i) => 
       sendMessageToUser(
         context,
         users[i], 
         msg + jsonMsgSuffix(jsons[i])
-      ).catch((e: Error) => console.error(e))
+      )
+        .then(() => {
+          recordNotifyLatency();
+        })
+        .catch((e: Error) => {
+          recordNotifyLatency();
+          getMetricFromRegistry<Counter>(metricsRegistry, NotifyMetrics.DISCORD_FAILURE).inc({ error: e.name }, 1);
+        })
     );
   } catch (e) {
     console.error(e);
@@ -45,10 +60,11 @@ export const handler: ServerlessFunctionSignature<TwilioContext, NotifyRequest>
 
   let timer = setTimeout(() => {
     console.log("Ungraceful finish: running out of time");
+    getMetricFromRegistry<Counter>(metricsRegistry, NotifyMetrics.NOTIFY_TIMEOUT).inc(1);
     callback(null, response);
   }, 9500);
 
   await Promise.all(promises);
   clearTimeout(timer);
   return callback(null, response);
-};
+});

packages/doorman-api/src/metrics/NotifyMetrics.ts

@@ -0,0 +1,25 @@
+import { Counter, Registry, Summary } from "prom-client";
+
+export enum NotifyMetrics {
+  DISCORD_LATENCY = "DiscordLatency",
+  DISCORD_FAILURE = "DiscordFailure",
+  NOTIFY_TIMEOUT = "NotifyTimeout"
+}
+
+export const registerMetrics = (metricsRegistry: Registry) => {
+  metricsRegistry.registerMetric(new Summary({
+    name: NotifyMetrics.DISCORD_LATENCY,
+    help: "Latency for the Discord API",
+  }));
+
+  metricsRegistry.registerMetric(new Counter({
+    name: NotifyMetrics.DISCORD_FAILURE,
+    help: "Failure calling discord API",
+    labelNames: ['error'],
+  }));
+
+  metricsRegistry.registerMetric(new Counter({
+    name: NotifyMetrics.NOTIFY_TIMEOUT,
+    help: "Timeout before all notify calls completed",
+  }));
+}

packages/doorman-api/src/utils/discord.ts

@@ -33,20 +33,15 @@ export const sendMessageToUser = async (
   userId: string,
   msg: string,
 ) => {
-  try {
-    const client = await getDiscordClient(context);
-    if (userCache[userId] === undefined) {
-      console.log("[UserCache] cache miss for", userId);
-      userCache[userId] = await client.users.fetch(userId);
-    } else {
-      console.log("[UserCache] cache hit for", userId);
-    }
-    const user = userCache[userId];
-    return user.send(msg);
-  } catch (e) {
-    console.log(e);
-    console.log(`Failed to send msg to ${userId}`);
+  const client = await getDiscordClient(context);
+  if (userCache[userId] === undefined) {
+    console.log("[UserCache] cache miss for", userId);
+    userCache[userId] = await client.users.fetch(userId);
+  } else {
+    console.log("[UserCache] cache hit for", userId);
   }
+  const user = userCache[userId];
+  return user.send(msg);
 };
 
 export const jsonMsgSuffix = (jsonString: string = "") => {