add basic prometheus metrics

.env.example

@@ -31,6 +31,19 @@ BOT_OWNERS=
 # used to log certain events (bot started, etc).
 LOG_WEBHOOK=
 
+# Optional: If set, enables Prometheus metrics
+# on the specified port (Under /metrics).
+# Note that no authentication can be configured;
+# you should use a reverse proxy if you need
+# BasicAuth or a different form of authentication.
+BOT_METRICS_PORT=
+
+# Optional: Set this to a channel ID if you
+# want Prometheus metrics to return `msg_ping`.
+# The bot will regularly send a message in that
+# channel.
+BOT_METRICS_MSG_PING_CHANNEL=
+
 # The URL from which your API and Web app are
 # publicly reachable. Do not add a trailing
 # slash to the URLs.

bot/package.json

@@ -22,6 +22,7 @@
     "form-data": "^4.0.0",
     "log75": "^2.2.0",
     "monk": "^7.3.4",
+    "prom-client": "^14.0.1",
     "ulid": "^2.3.0",
     "xlsx": "^0.17.3"
   },

bot/src/bot/modules/command_handler.ts

@@ -10,6 +10,7 @@ import MessageCommandContext from "../../struct/MessageCommandContext";
 import { fileURLToPath } from 'url';
 import { getOwnMemberInServer, hasPermForChannel } from "../util";
 import { isSudo, updateSudoTimeout } from "../commands/botadm";
+import { metrics } from "./metrics";
 
 // thanks a lot esm
 const filename = fileURLToPath(import.meta.url);
@@ -72,6 +73,8 @@ let commands: Command[];
         let cmd = commands.find(c => c.name == cmdName || (c.aliases?.indexOf(cmdName!) ?? -1) > -1);
         if (!cmd) return;
 
+        metrics.commands.inc();
+
         if (isSudo(msg.author!)) updateSudoTimeout(msg.author!);
 
         if (cmd.restrict == 'BOTOWNER' && ownerIDs.indexOf(msg.author_id) == -1) {

bot/src/bot/modules/metrics.ts

@@ -0,0 +1,73 @@
+import prom from 'prom-client';
+import http from 'http';
+import logger from '../logger';
+import { client } from '../..';
+import { decodeTime } from 'ulid';
+
+const PORT = Number(process.env.BOT_METRICS_PORT);
+
+prom.collectDefaultMetrics({ prefix: 'automod_' });
+
+const metrics = {
+    commands: new prom.Counter({ name: 'commands_executed', help: 'Amount of executed commands' }),
+    servers: new prom.Gauge({ name: 'server_count', help: 'Amount of servers the bot is in' }),
+    wsPing: new prom.Gauge({ name: 'ws_ping', help: 'WebSocket ping as returned by revolt.js' }),
+    msgPing: new prom.Gauge({ name: 'msg_ping', help: 'Amount of time it takes for the bot to send a message' }),
+}
+
+if (!isNaN(PORT)) {
+    logger.info(`Enabling Prometheus metrics on :${PORT}`);
+
+    const server = new http.Server();
+
+    server.on('request', async (req, res) => {
+        if (req.url == '/metrics') {
+            res.write(await prom.register.metrics());
+            res.end();
+        } else {
+            res.statusCode = 404;
+            res.write('404 not found');
+            res.end();
+        }
+    });
+
+    const setServerCount = () => metrics.servers.set(client.servers.size);
+
+    client.once('ready', setServerCount);
+    client.on('server/update', setServerCount);
+    client.on('server/delete', setServerCount);
+
+    const measureLatency = async () => {
+        const wsPing = client.websocket.ping;
+        if (wsPing != undefined) metrics.wsPing.set(wsPing);
+    }
+
+    client.once('ready', () => {
+        measureLatency();
+        setInterval(measureLatency, 10000);
+
+        if (process.env.BOT_METRICS_MSG_PING_CHANNEL) {
+            logger.info('BOT_METRICS_MSG_PING_CHANNEL is set, enabling message latency measuring');
+
+            const getMsgPing = async () => {
+                const channel = client.channels.get(process.env.BOT_METRICS_MSG_PING_CHANNEL!);
+                try {
+                    const now = Date.now();
+                    const msg = await channel?.sendMessage('Ping?');
+                    if (!msg) return;
+
+                    const delay = decodeTime(msg._id) - now;
+                    metrics.msgPing.set(delay);
+                    await msg.edit({ content: `Pong! ${delay}ms` });
+                } catch(e) { console.error(e) }
+            }
+
+            getMsgPing();
+            setInterval(getMsgPing, 30000);
+        }
+    });
+
+    server.listen(PORT, () => logger.done(`Prometheus metrics ready`));
+}
+
+export { metrics };

bot/src/index.ts

@@ -31,4 +31,5 @@ export { client }
     import('./bot/modules/tempbans');
     import('./bot/modules/user_scan');
     import('./bot/modules/api_communication');
+    import('./bot/modules/metrics');
 })();

bot/yarn.lock

@@ -150,6 +150,11 @@ base64-js@^1.3.1:
   resolved "https://registry.yarnpkg.com/base64-js/-/base64-js-1.5.1.tgz#1b1b440160a5bf7ad40b650f095963481903930a"
   integrity sha512-AKpaYlHn8t4SVbOHCy+b5+KKgvR4vrsD8vbvrbiQJps7fKDTkjkDry6ji0rUJjC0kzbNePLwzxq8iypo41qeWA==
 
+bintrees@1.0.1:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/bintrees/-/bintrees-1.0.1.tgz#0e655c9b9c2435eaab68bf4027226d2b55a34524"
+  integrity sha1-DmVcm5wkNeqraL9AJyJtK1WjRSQ=
+
 bl@^2.2.1:
   version "2.2.1"
   resolved "https://registry.yarnpkg.com/bl/-/bl-2.2.1.tgz#8c11a7b730655c5d56898cdc871224f40fd901d5"
@@ -498,6 +503,13 @@ process-nextick-args@~2.0.0:
   resolved "https://registry.yarnpkg.com/process-nextick-args/-/process-nextick-args-2.0.1.tgz#7820d9b16120cc55ca9ae7792680ae7dba6d7fe2"
   integrity sha512-3ouUOpQhtgrbOa17J7+uxOTpITYWaGP7/AhoR3+A+/1e9skrzelGi/dXzEYyvbxubEF6Wn2ypscTKiKJFFn1ag==
 
+prom-client@^14.0.1:
+  version "14.0.1"
+  resolved "https://registry.yarnpkg.com/prom-client/-/prom-client-14.0.1.tgz#bdd9583e02ec95429677c0e013712d42ef1f86a8"
+  integrity sha512-HxTArb6fkOntQHoRGvv4qd/BkorjliiuO2uSWC2KC17MUTKYttWdDoXX/vxOhQdkoECEM9BBH0pj2l8G8kev6w==
+  dependencies:
+    tdigest "^0.1.1"
+
 readable-stream@^2.3.5:
   version "2.3.7"
   resolved "https://registry.yarnpkg.com/readable-stream/-/readable-stream-2.3.7.tgz#1eca1cf711aef814c04f62252a36a62f6cb23b57"
@@ -559,6 +571,13 @@ string_decoder@~1.1.1:
   dependencies:
     safe-buffer "~5.1.0"
 
+tdigest@^0.1.1:
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/tdigest/-/tdigest-0.1.1.tgz#2e3cb2c39ea449e55d1e6cd91117accca4588021"
+  integrity sha1-Ljyyw56kSeVdHmzZEReszKRYgCE=
+  dependencies:
+    bintrees "1.0.1"
+
 tr46@~0.0.3:
   version "0.0.3"
   resolved "https://registry.yarnpkg.com/tr46/-/tr46-0.0.3.tgz#8184fd347dac9cdc185992f3a6622e14b9d9ab6a"

docker-compose.yml.example

@@ -19,6 +19,11 @@ services:
       - API_WS_TOKEN=${INTERNAL_API_TOKEN}
       - WEB_UI_URL=${PUBLIC_WEB_URL}
       - BOT_PREFIX
+      - BOT_METRICS_PORT
+      - BOT_METRICS_MSG_PING_CHANNEL
+    # Uncomment if you enabled Prometheus metrics
+    #ports:
+    #  - 127.0.0.1:${BOT_METRICS_PORT}:${BOT_METRICS_PORT}
     depends_on:
       - mongo
       - api