feat: add prometheus metrics

package.json

@@ -44,6 +44,7 @@
     "express": "4.19.2",
     "node-html-to-image": "4.0.0",
     "node-schedule": "2.1.1",
+    "prom-client": "15.1.3",
     "winston": "3.13.0"
   }
 }

pnpm-lock.yaml

@@ -29,6 +29,9 @@ importers:
       node-schedule:
         specifier: 2.1.1
         version: 2.1.1
+      prom-client:
+        specifier: 15.1.3
+        version: 15.1.3
       winston:
         specifier: 3.13.0
         version: 3.13.0
@@ -252,6 +255,10 @@ packages:
   '@octokit/types@13.5.0':
     resolution: {integrity: sha512-HdqWTf5Z3qwDVlzCrP8UJquMwunpDiMPt5er+QjGzL4hqr/vBVY/MauQgS1xWxCDT1oMx1EULyqxncdCY/NVSQ==}
 
+  '@opentelemetry/api@1.9.0':
+    resolution: {integrity: sha512-3giAOQvZiH5F9bMlMiv8+GSPMeqg0dbaeo58/0SlA9sxSqZhnUtxzX9/2FzyhS9sWQf5S0GJE0AKBrFqjpeYcg==}
+    engines: {node: '>=8.0.0'}
+
   '@pkgr/core@0.1.1':
     resolution: {integrity: sha512-cq8o4cWH0ibXh9VGi5P20Tu9XF/0fFXl9EUinr9QfTM7a7p0oTA4iJRCQWppXR1Pg8dSM0UCItCkPwsk9qWWYA==}
     engines: {node: ^12.20.0 || ^14.18.0 || >=16.0.0}
@@ -547,6 +554,9 @@ packages:
   before-after-hook@2.2.3:
     resolution: {integrity: sha512-NzUnlZexiaH/46WDhANlyR2bXRopNg4F/zuSA3OpZnllCUgRaOF2znDioDWrmbNVsuZk6l9pMquQB38cfBZwkQ==}
 
+  bintrees@1.0.2:
+    resolution: {integrity: sha512-VOMgTMwjAaUG580SXn3LacVgjurrbMme7ZZNYGSSV7mmtY6QQRh0Eg3pwIcntQ77DErK1L0NxkbetjcoXzVwKw==}
+
   body-parser@1.20.2:
     resolution: {integrity: sha512-ml9pReCu3M61kGlqoTm2umSXTlRTuGTx0bfYj+uIUKKYycG5NtSbeetV3faSU6R7ajOPw0g/J1PvK4qNy7s5bA==}
     engines: {node: '>= 0.8', npm: 1.2.8000 || >= 1.4.16}
@@ -1716,6 +1726,10 @@ packages:
     resolution: {integrity: sha512-7PiHtLll5LdnKIMw100I+8xJXR5gW2QwWYkT6iJva0bXitZKa/XMrSbdmg3r2Xnaidz9Qumd0VPaMrZlF9V9sA==}
     engines: {node: '>=0.4.0'}
 
+  prom-client@15.1.3:
+    resolution: {integrity: sha512-6ZiOBfCywsD4k1BN9IX0uZhF+tJkV8q8llP64G5Hajs4JOeVLPCwpPVcpXy3BwYiUGgyJzsJJQeOIv7+hDSq8g==}
+    engines: {node: ^16 || ^18 || >=20}
+
   proxy-addr@2.0.7:
     resolution: {integrity: sha512-llQsMLSUDUPT44jdrU/O37qlnifitDP+ZwrmmZcoSKyLKvtZxpyV0n2/bD/N4tBAAZ/gJEdZU7KMraoK1+XYAg==}
     engines: {node: '>= 0.10'}
@@ -1991,6 +2005,9 @@ packages:
   tar-stream@3.1.7:
     resolution: {integrity: sha512-qJj60CXt7IU1Ffyc3NJMjh6EkuCFej46zUqJ4J7pqYlThyd9bO0XBTmcOIhSzZJVWfsLks0+nle/j538YAW9RQ==}
 
+  tdigest@0.1.2:
+    resolution: {integrity: sha512-+G0LLgjjo9BZX2MfdvPfH+MKLCrxlXSYec5DaPYP1fe6Iyhf0/fSmJ0bFiZ1F8BT6cGXl2LpltQptzjXKWEkKA==}
+
   text-hex@1.0.0:
     resolution: {integrity: sha512-uuVGNWzgJ4yhRaNSiubPY7OjISw4sw4E5Uv0wbjp+OzcbmVU/rsT8ujgcXJhn9ypzsgr5vlzpPqP+MBBKcGvbg==}
 
@@ -2476,6 +2493,8 @@ snapshots:
     dependencies:
       '@octokit/openapi-types': 22.2.0
 
+  '@opentelemetry/api@1.9.0': {}
+
   '@pkgr/core@0.1.1': {}
 
   '@prisma/client@5.13.0(prisma@5.13.0)':
@@ -2816,6 +2835,8 @@ snapshots:
 
   before-after-hook@2.2.3: {}
 
+  bintrees@1.0.2: {}
+
   body-parser@1.20.2:
     dependencies:
       bytes: 3.1.2
@@ -4168,6 +4189,11 @@ snapshots:
 
   progress@2.0.3: {}
 
+  prom-client@15.1.3:
+    dependencies:
+      '@opentelemetry/api': 1.9.0
+      tdigest: 0.1.2
+
   proxy-addr@2.0.7:
     dependencies:
       forwarded: 0.2.0
@@ -4512,6 +4538,10 @@ snapshots:
       fast-fifo: 1.3.2
       streamx: 2.16.1
 
+  tdigest@0.1.2:
+    dependencies:
+      bintrees: 1.0.2
+
   text-hex@1.0.0: {}
 
   text-table@0.2.0: {}

src/events/client/onReady.ts

@@ -3,6 +3,7 @@ import { scheduleJob } from "node-schedule";
 import { ExtendedClient } from "../../interfaces/ExtendedClient";
 import { maintainSecurity } from "../../modules/maintainSecurity";
 import { postBirthdays } from "../../modules/postBirthdays";
+import { Prometheus } from "../../modules/prometheus";
 import { registerCommands } from "../../utils/registerCommands";
 import { sendDebugMessage } from "../../utils/sendDebugMessage";
 
@@ -14,6 +15,7 @@ import { sendDebugMessage } from "../../utils/sendDebugMessage";
 export const onReady = async (bot: ExtendedClient) => {
   await sendDebugMessage(bot, `Logged in as ${bot.user?.tag}`);
   await registerCommands(bot);
+  bot.analytics = new Prometheus(bot);
 
   // Daily at 9am PST
   scheduleJob("birthdays", "0 9 * * *", async () => await postBirthdays(bot));

src/events/guild/onGuildCreate.ts

@@ -15,4 +15,5 @@ export const onGuildCreate = async function (
   await bot.env.debugHook.send({
     content: `JOINED GUILD: ${guild.name} (${guild.id}) - owned by ${owner?.displayName} (${owner.id})`
   });
+  bot.analytics.updateGuilds(bot);
 };

src/events/guild/onGuildDelete.ts

@@ -36,6 +36,7 @@ export const onGuildDelete = async function (
     await bot.db.security
       .deleteMany({ where: { serverId: guild.id } })
       .catch(() => null);
+    bot.analytics.updateGuilds(bot);
   } catch (err) {
     await errorHandler(bot, "on guild delete", err);
   }

src/events/interaction/onInteraction.ts

@@ -35,6 +35,7 @@ export const onInteraction = async (
       );
       return;
     }
+    bot.analytics.commandUsed();
     if (interaction.isChatInputCommand()) {
       handleChatInputCommand(bot, interaction);
     }

src/interfaces/ExtendedClient.ts

@@ -4,6 +4,8 @@ import { Client, WebhookClient } from "discord.js";
 import { Command } from "./Command";
 import { Context } from "./Context";
 
+import type { Prometheus } from "../modules/prometheus.js";
+
 export interface ExtendedClient extends Client {
   env: {
     token: string;
@@ -12,6 +14,7 @@ export interface ExtendedClient extends Client {
     devMode: boolean;
   };
   db: PrismaClient;
+  analytics: Prometheus;
   commands: Command[];
   contexts: Context[];
   configs: { [serverId: string]: Omit<configs, "id"> };

src/modules/prometheus.ts

@@ -0,0 +1,29 @@
+import client, { Counter, Gauge } from "prom-client";
+import type { ExtendedClient } from "../interfaces/ExtendedClient.js";
+
+export class Prometheus {
+  private client = client;
+  private guilds: Gauge;
+  private commands: Counter;
+
+  constructor(bot: ExtendedClient) {
+    this.guilds = new Gauge({
+      name: "guilds",
+      help: "The number of guilds the bot is in."
+    });
+    this.guilds.set(bot.guilds.cache.size);
+    this.commands = new Counter({
+      name: "commands",
+      help: "The number of commands that have been used since last boot."
+    });
+    this.client.collectDefaultMetrics();
+  }
+
+  public commandUsed() {
+    this.commands.inc();
+  }
+
+  public updateGuilds(bot: ExtendedClient) {
+    this.guilds.set(bot.guilds.cache.size);
+  }
+}

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 {