adding seperate metrics server

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

@@ -1,6 +1,6 @@
 const metrics = require('./metrics')
 
-function middleware (request, response, done) {
+function middleware(request, response, done) {
   var start = process.hrtime()
 
   response.on('finish', function () {
@@ -10,15 +10,16 @@ function middleware (request, response, done) {
   return done()
 };
 
-function instrument (server, options) {
+function instrument(server, options) {
   server.use(middleware)
-  server.get(options.url, (req, res) => {
+  let metricsEndpointServer = options.metricsServer || server;
+  metricsEndpointServer.get(options.url, (req, res) => {
     res.header('content-type', 'text/plain; charset=utf-8')
     return res.send(metrics.summary())
   })
 }
 
-function instrumentable (server) {
+function instrumentable(server) {
   return server && server.defaultConfiguration && server.use
 }
 

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

@@ -1,7 +1,7 @@
 const defaults = require('./defaults')
 const metrics = require('./metrics')
 
-function sendMetrics (request, response) {
+function sendMetrics(request, response) {
   response.writeHead(200, {
     'Content-Type': 'text/plain; charset=utf-8'
   })
@@ -10,15 +10,16 @@ function sendMetrics (request, response) {
   response.end()
 }
 
-function observeMetrics (request, response) {
+function observeMetrics(request, response) {
   var start = process.hrtime()
   response.on('finish', () => {
     metrics.observe(request.method, request.url, response.statusCode, start)
   })
 }
 
-function instrument (server, options) {
-  server.on('request', (request, response) => {
+function instrument(server, options) {
+  let metricsEndpointServer = options.metricsServer || server;
+  metricsEndpointServer.on('request', (request, response) => {
     if (request.url === options.url) {
       sendMetrics(request, response)
     } else {
@@ -27,7 +28,7 @@ function instrument (server, options) {
   })
 }
 
-function instrumentable (server) {
+function instrumentable(server) {
   return server
 }
 

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"
   }
 }

test/assert-expectations.js

@@ -1,7 +1,7 @@
 const request = require('request')
 const should = require('chai').should()
 
-module.exports = function (options) {
+module.exports = function(options) {
   it('should return 200 for /', (done) => {
     request('http://localhost:3000/', (e, r, b) => {
       r.statusCode.should.equal(200)
@@ -17,7 +17,8 @@ module.exports = function (options) {
   })
 
   it('should return 200 for ' + options.url, (done) => {
-    request('http://localhost:3000' + options.url, (e, r, b) => {
+    let metricsPort = options.metricsServer ? 3001 : 3000;
+    request('http://localhost:' + metricsPort + options.url, (e, r, b) => {
       r.statusCode.should.equal(200)
       should.exist(r.headers['content-type'])
       r.headers['content-type'].should.equal('text/plain; charset=utf-8')
@@ -29,4 +30,13 @@ module.exports = function (options) {
       return done(e)
     })
   })
+
+  if (options.metricsServer) {
+    it('should return 404 for /metrics on 3000', (done) => {
+      request('http://localhost:3000/metrics', (e, r, b) => {
+        r.statusCode.should.equal(404)
+        return done(e)
+      });
+    });
+  }
 }

test/express.js

@@ -4,8 +4,10 @@ const epithemeus = require('../index')
 const assertExpectations = require('./assert-expectations')
 const assert = require('chai').assert
 const libExpress = require('../lib/express')
+const request = require('request')
+const should = require('chai').should()
 
-function setup (options) {
+function setup(options) {
   return describe('express ' + options.url, () => {
     before((done) => {
       const app = express()
@@ -16,7 +18,13 @@ function setup (options) {
       app.get('/resource/:id', (req, res) => {
         res.send()
       })
-      this.server = app.listen(3000, done)
+      this.server = app.listen(3000, () => {
+        if (options.metricsServer) {
+          options.metricsServer.listen(3001, done);
+        } else {
+          done()
+        }
+      });
     })
 
     after((done) => {
@@ -32,11 +40,18 @@ setup({
   url: '/xxx'
 })
 
+setup({
+  url: '/metrics',
+  metricsServer: express()
+})
+
 describe('express should check "instrumentablity" properly', () => {
   it('should return true when express conditions are correct', () => {
     // Arrange
     const server = () => {}
-    server.defaultConfiguration = { sample: true }
+    server.defaultConfiguration = {
+      sample: true
+    }
     server.use = () => {}
 
     // Act
@@ -69,7 +84,9 @@ describe('express should check "instrumentablity" properly', () => {
   it('should return false when server does not have a use function', () => {
     // Arrange
     const server = () => {}
-    server.defaultConfiguration = { sample: true }
+    server.defaultConfiguration = {
+      sample: true
+    }
 
     // Act
     const actual = libExpress.instrumentable(server)