implement a helper to fetch metrics

packages/doorman-api/src/common/DoormanHandler.ts

@@ -1,6 +1,7 @@
 import { ServerlessCallback, ServerlessFunctionSignature } from "@twilio-labs/serverless-runtime-types/types";
-import { PrometheusContentType, Registry, Pushgateway, Summary } from "prom-client";
+import { PrometheusContentType, Registry, Pushgateway, Summary, Counter } from "prom-client";
 import { DoormanLambdaContext } from "./DoormanHandlerContext";
+import { shouldBlockRequest } from "../utils/blockUserAgent";
 
 export type BaseEvent = { request: { cookies: {}; headers: {}; }; }
 
@@ -13,6 +14,12 @@ export type DoormanLambda<T extends DoormanLambdaContext, U extends BaseEvent> =
 
 export enum CommonMetrics {
   RUNTIME = "FunctionRuntime",
+  BLOCKED_REQUEST = "BlockedRequest",
+  HTTP_CLIENT_ERROR = "HttpClientError",
+};
+
+export function getMetricFromRegistry<T>(metricsRegistry: Registry, metric: string): T {
+  return metricsRegistry.getSingleMetric(metric) as T;
 };
 
 /**
@@ -34,7 +41,18 @@ export function withMetrics<T extends DoormanLambdaContext, U extends BaseEvent>
       help: "Runtime of the function",
     }));
 
-    const summaryTimer = (metricsRegistry.getSingleMetric(CommonMetrics.RUNTIME) as Summary).startTimer();
+    metricsRegistry.registerMetric(new Counter({
+      name: CommonMetrics.BLOCKED_REQUEST,
+      help: "Blocked requests",
+    }));
+
+    metricsRegistry.registerMetric(new Counter({
+      name: CommonMetrics.HTTP_CLIENT_ERROR,
+      help: "Client side HTTP error",
+      labelNames: [ "ErrorCode" ],
+    }));
+
+    const summaryTimer = getMetricFromRegistry<Summary>(metricsRegistry, CommonMetrics.RUNTIME).startTimer();
 
     const startTime = Date.now();
     console.log(`[CommonHandler] started handler at ${startTime}`);
@@ -46,11 +64,28 @@ export function withMetrics<T extends DoormanLambdaContext, U extends BaseEvent>
         callbackResult = [err, payload];
       }
 
+      // block requests before we even call the handler
+      if (shouldBlockRequest(event)) {
+        getMetricFromRegistry<Counter>(metricsRegistry, CommonMetrics.BLOCKED_REQUEST).inc(1);
+        const response = new Twilio.Response();
+        response.setStatusCode(200);
+        callbackResult = [null, response];
+      } else {
         await handler(context, event, tempCallback, metricsRegistry);
+      }
 
       if (!callbackResult) {
         reject("No callback was given");
       }
+
+      let statusCode: number | undefined = (callbackResult?.[1] as any)?.statusCode;
+
+      if (statusCode && statusCode >= 400) {
+        getMetricFromRegistry<Counter>(metricsRegistry, CommonMetrics.HTTP_CLIENT_ERROR).inc({
+          ErrorCode: statusCode,
+        }, 1);
+      }
+
       resolve(callbackResult as Parameters<ServerlessCallback>);
     });
 
@@ -66,7 +101,7 @@ export function withMetrics<T extends DoormanLambdaContext, U extends BaseEvent>
     console.log(`[CommonHandler] there is ${remainingTime} ms left to send metrics`);
 
     let metricsTimeout = setTimeout(() => {
-      console.log("[CommonHandler] cutting it too close, abandoning metrics");
+      console.error("[CommonHandler] cutting it too close, abandoning metrics");
       callback(...result);
     }, remainingTime - 250);
 
@@ -74,6 +109,7 @@ export function withMetrics<T extends DoormanLambdaContext, U extends BaseEvent>
 
     console.log("[CommonHandler] attempting to push metrics...");
     try {
+      console.log(await getMetricFromRegistry<Summary>(metricsRegistry, CommonMetrics.RUNTIME).get());
       await pushGateway.push({
         jobName: functionName,
         groupings: {
@@ -82,7 +118,7 @@ export function withMetrics<T extends DoormanLambdaContext, U extends BaseEvent>
       });
       console.log("[CommonHandler] pushed metrics successfully");
     } catch (e: any) {
-      console.log("[CommonHandler] failed to push metrics, quietly discarding them", e);
+      console.error("[CommonHandler] failed to push metrics, quietly discarding them", e);
     }
     
     clearTimeout(metricsTimeout);

packages/doorman-client/src/functions/buzzer-activated.ts

@@ -15,7 +15,7 @@ import VoiceResponse from 'twilio/lib/twiml/VoiceResponse';
 import { DoorStatus } from '../../../doorman-api/src/types/DoorStatus';
 import { StatusResponse } from '../../../doorman-api/src/functions/api/door/status';
 import { InfoResponseClient } from '../../../doorman-api/src/functions/api/door/info';
-import { withMetrics } from '../../../doorman-api/src/common/DoormanHandler';
+import { getMetricFromRegistry, withMetrics } from '../../../doorman-api/src/common/DoormanHandler';
 import { Counter, Summary } from 'prom-client';
 import { BuzzerActivatedMetrics, registerMetrics } from '../metrics/BuzzerActivatedMetrics';
 
@@ -43,7 +43,9 @@ export const handler: ServerlessFunctionSignature<TwilioContext, BuzzerDialEvent
   if (!config || !config.door) {
     let twiml = new Twilio.twiml.VoiceResponse();
     twiml.reject();
-    (metricsRegistry.getSingleMetric(BuzzerActivatedMetrics.CALL_REJECTED) as Counter).inc({ From: event.From }, 1);
+
+    getMetricFromRegistry<Counter>(metricsRegistry, BuzzerActivatedMetrics.CALL_REJECTED)
+      .inc({ From: event.From }, 1);
     callback(null, twiml);
     return;
   }
@@ -62,8 +64,11 @@ export const handler: ServerlessFunctionSignature<TwilioContext, BuzzerDialEvent
 
   const unlockPromise = new Promise<VoiceResponse>((resolve, reject) => {
     intervals.push(setInterval(() => {
-      (metricsRegistry.getSingleMetric(BuzzerActivatedMetrics.POLL_ATTEMPTS) as Counter).inc({ door: config.door }, 1);
+      getMetricFromRegistry<Counter>(metricsRegistry, BuzzerActivatedMetrics.POLL_ATTEMPTS)
-      const recordPollLatency = (metricsRegistry.getSingleMetric(BuzzerActivatedMetrics.POLL_LATENCY) as Summary).startTimer({ door: config.door });
+        .inc({ door: config.door }, 1);
+
+      const recordPollLatency = getMetricFromRegistry<Summary>(metricsRegistry, BuzzerActivatedMetrics.POLL_LATENCY)
+        .startTimer({ door: config.door });
       
       fetch(context.DOORMAN_URL + `/api/door/status?door=${config.door}`)
         .then(res => res.json())
@@ -79,7 +84,8 @@ export const handler: ServerlessFunctionSignature<TwilioContext, BuzzerDialEvent
               console.log(
                 invokeId, "UnlockPromise: I was the fastest, so I will attempt to notify discord users before resolving with unlock"
               );
-              (metricsRegistry.getSingleMetric(BuzzerActivatedMetrics.API_UNLOCK) as Counter).inc({ door: config.door }, 1);
+              getMetricFromRegistry<Counter>(metricsRegistry, BuzzerActivatedMetrics.API_UNLOCK)
+                .inc({ door: config.door }, 1);
               await notifyAllDiscord(context, config, `🔓 Doorman buzzed someone up @ Door "${config.door}"`, metricsRegistry, JSON.stringify(body.fingerprint));
   
               resolve(twiml);
@@ -99,7 +105,8 @@ export const handler: ServerlessFunctionSignature<TwilioContext, BuzzerDialEvent
 
       if (!discordLock) {
         discordLock = true;
-        (metricsRegistry.getSingleMetric(BuzzerActivatedMetrics.DIAL_THROUGH) as Counter).inc({ door: config.door }, 1);
+        getMetricFromRegistry<Counter>(metricsRegistry, BuzzerActivatedMetrics.DIAL_THROUGH)
+          .inc({ door: config.door }, 1);
 
         console.log(
           invokeId, "GracefulFallbackPromise: I was the fastest, so I will attempt to notify discord users before resolving with a call"
@@ -121,8 +128,11 @@ export const handler: ServerlessFunctionSignature<TwilioContext, BuzzerDialEvent
 
   const ungracefulFallbackPromise = new Promise<VoiceResponse>((resolve, reject) => {
     timeouts.push(setTimeout(async () => {
-      (metricsRegistry.getSingleMetric(BuzzerActivatedMetrics.RESULT_NOTIFICATION_FATE_UNKNOWN) as Counter).inc({ door: config.door }, 1);
+      getMetricFromRegistry<Counter>(metricsRegistry, BuzzerActivatedMetrics.RESULT_NOTIFICATION_FATE_UNKNOWN)
-      (metricsRegistry.getSingleMetric(BuzzerActivatedMetrics.DIAL_THROUGH) as Counter).inc({ door: config.door }, 1);
+        .inc({ door: config.door }, 1);
+      
+      getMetricFromRegistry<Counter>(metricsRegistry, BuzzerActivatedMetrics.DIAL_THROUGH)
+        .inc({ door: config.door }, 1);
 
       const twiml = dialFallbackTwiml(config);
       console.error(