adding seperate metrics server and use prometheus-gc-stats

Author: hsingh6764

README.md

@@ -46,6 +46,7 @@ The first argument represents the server of the middleware.
 The second argument is optional, and allows some configuration of epimetheus
 
 - `url` - the url on which to serve metrics. Defaults to `/metrics`.
+- `metricsServer` - which server to attach option.url to. (Can be really useful if you like to run metrics endpoint on seperate port);
 
 See the following examples of use with [http](#http), [express](#express), [hapi](#hapi) and [restify](#restify).
 

lib/express.js

@@ -12,7 +12,8 @@ function middleware (request, response, done) {
 
 function instrument (server, options) {
   server.use(middleware)
-  server.get(options.url, (req, res) => {
+  let mertricsEndpointServer = options.metricsServer || server;
+  mertricsEndpointServer.get(options.url, (req, res) => {
     res.header('content-type', 'text/plain; charset=utf-8')
     return res.send(metrics.summary())
   })

lib/hapi.js

@@ -3,7 +3,8 @@ const metrics = require('./metrics')
 function plugin (options) {
   var plugin = {
     register: (server, o, done) => {
-      server.route({
+      let mertricsEndpointServer = options.metricsServer || server;
+      mertricsEndpointServer.route({
         method: 'GET',
         path: options.url,
         handler: (req, reply) => {

lib/http.js

@@ -18,7 +18,8 @@ function observeMetrics (request, response) {
 }
 
 function instrument (server, options) {
-  server.on('request', (request, response) => {
+  let mertricsEndpointServer = options.metricsServer || server;
+  mertricsEndpointServer.on('request', (request, response) => {
     if (request.url === options.url) {
       sendMetrics(request, response)
     } else {

lib/metrics.js

@@ -11,6 +11,10 @@ const metric = {
   }
 }
 
+const gcStats = require('prometheus-gc-stats');
+const startGcStats = gcStats(client.register);
+startGcStats();
+
 function ms (start) {
   var diff = process.hrtime(start)
   return Math.round((diff[0] * 1e9 + diff[1]) / 1000000)

lib/restify.js

@@ -14,8 +14,9 @@ function middleware (request, response, done) {
 };
 
 function instrument (server, options) {
+  let mertricsEndpointServer = options.metricsServer || server;
   server.use(middleware)
-  server.get(options.url, (req, res) => {
+  mertricsEndpointServer.get(options.url, (req, res) => {
     res.setHeader('Content-Type', 'text/plain; charset=utf-8')
     /**
      * Using send uses the native Node handlers rather than the restify one

package.json

@@ -42,6 +42,7 @@
     "sinon": "^2.3.6"
   },
   "dependencies": {
-    "prom-client": "^10.0.0"
+    "prom-client": "^11.1.1",
+    "prometheus-gc-stats": "^0.5.1"
   }
 }