add prometheus metrics to bridge

.env.example

@@ -51,6 +51,10 @@ LOG_WEBHOOK=
 # BasicAuth or a different form of authentication.
 BOT_METRICS_PORT=
 
+# Same as above, but for the bridge service.
+# Make sure the ports don't overlap!
+BRIDGE_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

bridge/package.json

@@ -22,6 +22,7 @@
     "form-data": "^4.0.0",
     "log75": "^2.2.0",
     "monk": "^7.3.4",
+    "prom-client": "^14.0.1",
     "revolt-api": "^0.5.3-rc.8",
     "smart-replace": "^1.0.2",
     "ulid": "^2.3.0"

bridge/src/discord/events.ts

@@ -9,6 +9,7 @@ import FormData from 'form-data';
 import { discordFetchUser, revoltFetchMessage } from "../util";
 import { TextChannel } from "discord.js";
 import { smartReplace } from "smart-replace";
+import { metrics } from "../metrics";
 
 const MAX_BRIDGED_FILE_SIZE = 8_000_000; // 8 MB
 const RE_MENTION_USER = /<@!*[0-9]+>/g;
@@ -31,6 +32,7 @@ client.on('messageDelete', async message => {
         if (!targetMsg) return logger.debug(`Discord: Could not fetch message from Revolt`);
 
         await targetMsg.delete();
+        metrics.messages.inc({ source: 'discord', type: 'delete' });
     } catch(e) {
         console.error(e);
     }
@@ -57,6 +59,7 @@ client.on('messageUpdate', async (oldMsg, newMsg) => {
         if (!targetMsg) return logger.debug(`Discord: Could not fetch message from Revolt`);
 
         await targetMsg.edit({ content: newMsg.content ? await renderMessageBody(newMsg.content) : undefined });
+        metrics.messages.inc({ source: 'discord', type: 'edit' });
     } catch(e) {
         console.error(e);
     }
@@ -182,6 +185,8 @@ client.on('messageCreate', async message => {
                         $set: { "revolt.messageId": res.data._id },
                     }
                 );
+
+                metrics.messages.inc({ source: 'discord', type: 'create' });
             })
             .catch(async e => {
                 console.error(`Failed to send message`, e.response.data);

bridge/src/index.ts

@@ -24,6 +24,7 @@ for (const v of [ 'REVOLT_TOKEN', 'DISCORD_TOKEN', 'DB_STRING' ]) {
 }
 
 (async () => {
+    import('./metrics');
     const [ revolt, discord ] = await Promise.allSettled([
         loginRevolt(),
         loginDiscord(),

bridge/src/metrics.ts

@@ -0,0 +1,32 @@
+import prom from 'prom-client';
+import http from 'http';
+import { logger } from '.';
+
+const PORT = Number(process.env.BRIDGE_METRICS_PORT);
+
+prom.collectDefaultMetrics({ prefix: 'automod_bridge_' });
+
+const metrics = {
+    messages: new prom.Counter({ name: 'messages', help: 'Bridged message events', labelNames: [ 'source', 'type' ] }),
+}
+
+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();
+        }
+    });
+
+    server.listen(PORT, () => logger.done(`Prometheus metrics ready`));
+}
+
+export { metrics }

bridge/src/revolt/events.ts

@@ -6,6 +6,7 @@ import GenericEmbed from "../types/GenericEmbed";
 import { SendableEmbed } from "revolt-api";
 import { clipText, discordFetchMessage, revoltFetchUser } from "../util";
 import { smartReplace } from "smart-replace";
+import { metrics } from "../metrics";
 
 const RE_MENTION_USER = /<@[0-9A-HJ-KM-NP-TV-Z]{26}>/g;
 const RE_MENTION_CHANNEL = /<#[0-9A-HJ-KM-NP-TV-Z]{26}>/g;
@@ -31,8 +32,10 @@ client.on('message/delete', async id => {
             const client = new WebhookClient({ id: bridgeCfg.discordWebhook.id, token: bridgeCfg.discordWebhook.token });
             await client.deleteMessage(bridgedMsg.discord.messageId);
             client.destroy();
+            metrics.messages.inc({ source: 'revolt', type: 'delete' });
         } else if (targetMsg.deletable) {
             targetMsg.delete();
+            metrics.messages.inc({ source: 'revolt', type: 'delete' });
         } else logger.debug(`Revolt: Unable to delete Discord message`);
     } catch(e) {
         console.error(e);
@@ -61,6 +64,8 @@ client.on('message/update', async message => {
         const client = new WebhookClient({ id: bridgeCfg.discordWebhook.id, token: bridgeCfg.discordWebhook.token });
         await client.editMessage(targetMsg, { content: await renderMessageBody(message.content), allowedMentions: { parse: [ ] } });
         client.destroy();
+
+        metrics.messages.inc({ source: 'revolt', type: 'edit' });
     } catch(e) { console.error(e) }
 });
 
@@ -203,6 +208,8 @@ client.on('message', async message => {
                     "discord.messageId": res.id
                 }
             });
+
+            metrics.messages.inc({ source: 'revolt', type: 'create' });
         })
         .catch(async e => {
             console.error('Failed to execute webhook:', e?.response?.data ?? e);

bridge/yarn.lock

@@ -158,6 +158,11 @@ 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"
@@ -464,6 +469,13 @@ 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"
@@ -532,6 +544,13 @@ 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"
+
 tiny-glob@^0.2.9:
   version "0.2.9"
   resolved "https://registry.yarnpkg.com/tiny-glob/-/tiny-glob-0.2.9.tgz#2212d441ac17928033b110f8b3640683129d31e2"

docker-compose.yml.example

@@ -52,6 +52,7 @@ services:
       - DISCORD_TOKEN=${BOT_TOKEN_DISCORD}
       - DB_STRING=mongodb://mogus:${DB_PASS}@mongo:27017/admin
       - NODE_ENV=production
+      - BRIDGE_METRICS_PORT
     restart: unless-stopped
     depends_on:
       - mongo