GITBOOK-216: change request with no subject merged in GitBook

docs/gitbook/SUMMARY.md

@@ -48,7 +48,8 @@
   * [Remove Dependency](guide/flows/remove-dependency.md)
   * [Ignore Dependency](guide/flows/ignore-dependency.md)
   * [Remove Child Dependency](guide/flows/remove-child-dependency.md)
-* [Metrics](guide/metrics/metrics.md)
+* [Metrics](guide/metrics/README.md)
+  * [Prometheus](guide/metrics/prometheus.md)
 * [Rate limiting](guide/rate-limiting.md)
 * [Parallelism and Concurrency](guide/parallelism-and-concurrency.md)
 * [Retrying failing jobs](guide/retrying-failing-jobs.md)

docs/gitbook/guide/metrics/metrics.md → docs/gitbook/guide/metrics/README.md

@@ -1,7 +1,10 @@
+---
+description: Built-in Metrics for your queues.
+---
+
 # Metrics
 
-BullMQ provides a simple metrics gathering functionality that allows you to track the performance of your queues.
-Workers can count the number of jobs they have processed per minute and store this data in a list to be consumed later.
+BullMQ provides a simple metrics gathering functionality that allows you to track the performance of your queues. Workers can count the number of jobs they have processed per minute and store this data in a list to be consumed later.
 
 You enable it on the worker settings by specifying how many data points you want to keep. We recommend 2 weeks of metrics data which should take a very small amount of space, just around 120Kb of RAM per queue.
 
@@ -43,5 +46,4 @@ const metrics = await queue.getMetrics('completed');
 */
 ```
 
-Note that the `getMetrics` method also accepts a `start` and `end` argument (`0` and `-1` by default), that you can
-use if you want to implement pagination.
+Note that the `getMetrics` method also accepts a `start` and `end` argument (`0` and `-1` by default), that you can use if you want to implement pagination.

docs/gitbook/guide/metrics/prometheus.md

@@ -0,0 +1,88 @@
+---
+description: How to use the built-in prometheus exporter
+---
+
+# Prometheus
+
+BullMQ provides a simple API that can be used to export metrics to Prometheus. You just need to create an endpoint in your webserver that calls exportPrometheusMetrics() and configure prometheus to consume from this endpoint. For example using vanilla NodeJS:
+
+```typescript
+import http from "http";
+import { Queue } from "bullmq";
+
+const queue = new Queue("my-queue");
+
+const server = http.createServer(
+  async (req: http.IncomingMessage, res: http.ServerResponse) => {
+    try {
+      if (req.url === "/metrics" && req.method === "GET") {
+        const metrics = await queue.exportMetrics();
+
+        res.writeHead(200, {
+          "Content-Type": "text/plain",
+          "Content-Length": Buffer.byteLength(metrics),
+        });
+        res.end(metrics);
+      } else {
+        res.writeHead(404);
+        res.end("Not Found");
+      }
+    } catch (err: unknown) {
+      res.writeHead(500);
+      res.end(`Error: ${err instanceof Error ? err.message : "Unknown error"}`);
+    }
+  }
+);
+
+const PORT = process.env.PORT || 3000;
+
+server.listen(PORT, () => {
+  console.log(`Prometheus metrics server running on port ${PORT}`);
+  console.log(`Metrics available at http://localhost:${PORT}/metrics`);
+});
+```
+
+If you curl to the endpoint like this: 
+
+```bash
+curl http://localhost:3000/metrics
+```
+
+You will get an output similar to this:
+
+```
+HELP bullmq_job_count Number of jobs in the queue by state
+TYPE bullmq_job_count gauge
+bullmq_job_count{queue="my-queue", state="waiting"} 5 
+bullmq_job_count{queue="my-queue", state="active"} 3 
+bullmq_job_count{queue="my-queue", state="completed"} 12 
+bullmq_job_count{queue="my-queue", state="failed"} 2
+```
+
+If you use ExpressJS the code is a bit simpler:
+
+```typescript
+import express from 'express';
+import { Queue } from './src/queue';
+
+const app = express();
+const queue = new Queue('my-queue');
+
+app.get('/metrics', async (req, res) => {
+  try {
+    const metrics = await queue.exportMetrics();
+    res.set('Content-Type', 'text/plain');
+    res.send(metrics);
+  } catch (err) {
+    res.status(500).send(err.message);
+  }
+});
+
+const PORT = process.env.PORT || 3000;
+
+app.listen(PORT, () => {
+  console.log(`Prometheus metrics server running on port ${PORT}`);
+  console.log(`Metrics available at http://localhost:${PORT}/metrics`);
+});
+```
+