Merge pull request #101 from derangeddk/add-metricsapp-option

Add metricsapp option

README.md

@@ -89,6 +89,7 @@ Additional options for **summary**:
   to keep `express-prom-bundle` runnable using confit (e.g. with kraken.js) without writing any JS code,
   see [advanced example](https://github.com/jochen-schweizer/express-prom-bundle/blob/master/advanced-example.js)
 * **promRegistry**: Optional `promClient.Registry` instance to attach metrics to. Defaults to global `promClient.register`.
+* **metricsApp**: Allows you to attach the metrics endpoint to a different express app. You probably want to use it in combination with `autoregister: false`.
 
 ### More details on includePath option
 

spec/index.spec.js

@@ -590,5 +590,23 @@ describe('index', () => {
           });
       });
     });
+
+    it('additional metricsApp can be used', done => {
+      const app = express();
+      const metricsApp = express();
+      const bundled = bundle({metricsApp});
+
+      app.use(bundled);
+
+      const agent = supertest(app);
+      const metricsAgent = supertest(metricsApp);
+      agent.get('/').end(() => {
+        metricsAgent.get('/metrics').end((err, res) => {
+          expect(res.status).toBe(200);
+          expect(res.text).toMatch(/status_code="404"/);
+          done();
+        });
+      });
+    });
   });
 });

src/index.js

@@ -68,7 +68,8 @@ function main(opts) {
       formatStatusCode: main.normalizeStatusCode,
       metricType: 'histogram',
       promClient: {},
-      promRegistry: promClient.register
+      promRegistry: promClient.register,
+      metricsApp: null,
     }, opts
   );
 
@@ -204,6 +205,13 @@ function main(opts) {
     next();
   };
 
+  if (opts.metricsApp) {
+    opts.metricsApp.get(opts.metricsPath || '/metrics', async (req, res, next) => {
+      res.set('Content-Type', opts.promRegistry.contentType);
+      return res.end(await opts.promRegistry.metrics());
+    });
+  }
+
   middleware.metrics = metrics;
   middleware.promClient = promClient;
   middleware.metricsMiddleware = metricsMiddleware;

types/index.d.ts

@@ -1,6 +1,6 @@
 // TypeScript Version: 2.8
 
-import { Request, RequestHandler, Response } from 'express';
+import { Request, RequestHandler, Response, Express } from 'express';
 import { DefaultMetricsCollectorConfiguration, Registry } from 'prom-client';
 
 export {};
@@ -49,6 +49,7 @@ declare namespace express_prom_bundle {
     formatStatusCode?: NormalizeStatusCodeFn;
     transformLabels?: TransformLabelsFn;
     urlPathReplacement?: string;
+    metricsApp?: Express;
 
     // https://github.com/disjunction/url-value-parser#options
     urlValueParser?: {

types/test.ts

@@ -1,10 +1,11 @@
-import { Request, RequestHandler, Response } from 'express';
+import * as express from 'express';
+
 import * as promClient from 'prom-client';
 
 import * as promBundle from 'express-prom-bundle';
 
 // $ExpectType Middleware
-const middleware: RequestHandler = promBundle({ includeMethod: true });
+const middleware: express.RequestHandler = promBundle({ includeMethod: true });
 
 // $ExpectType: string
 middleware.name;
@@ -57,7 +58,8 @@ promBundle({
   normalizePath: [
     ['^/foo', '/example'] // replace /foo with /example
   ],
-  formatStatusCode: (res: Response) => res.statusCode + 100
+  formatStatusCode: (res: express.Response) => res.statusCode + 100,
+  metricsApp: express()
 });
 
 promClient.register.clear();
@@ -79,14 +81,14 @@ promBundle({
 type Writable<T> = { -readonly [K in keyof T]: T[K] };
 const wPromBundle: Writable<promBundle> = promBundle;
 
-wPromBundle.normalizePath = (req: Request, opts: promBundle.Opts) => {
+wPromBundle.normalizePath = (req: express.Request, opts: promBundle.Opts) => {
   const path = promBundle.normalizePath(req, opts);
 
   // count all docs as one path, but /docs/login as a separate one
   return path.match(/^\/docs/) && !path.match(/^\/login/) ? '/docs/*' : path;
 };
 
-wPromBundle.normalizeStatusCode = (res: Response) => res.statusCode.toString();
+wPromBundle.normalizeStatusCode = (res: express.Response) => res.statusCode.toString();
 
 // $ExpectType RequestHandler
 promBundle.clusterMetrics();