feat: add prometheus metrics

src/server/serve.ts

@@ -6,6 +6,7 @@ import https from "https";
 import { Octokit } from "@octokit/rest";
 import { GuildTextBasedChannel } from "discord.js";
 import express from "express";
+import { register } from "prom-client";
 
 import { IgnoredActors, ThankYou } from "../config/Github";
 import { ExtendedClient } from "../interfaces/ExtendedClient";
@@ -47,6 +48,15 @@ export const serve = async (bot: ExtendedClient) => {
     res.send("bot online!");
   });
 
+  app.get("/metrics", async (_req, res) => {
+    try {
+      res.set("Content-Type", register.contentType);
+      res.end(await register.metrics());
+    } catch (err) {
+      res.status(500).end(err);
+    }
+  });
+
   app.post("/kofi", async (req, res) => {
     const payload = JSON.parse(req.body.data);
     const {