remove a duplicate cluster docs piece, versio 4.2.1

commit bc65dc45cb
Author: Konstantin Pogorelov <or@pluseq.com>
Date:   Sat Aug 25 12:57:15 2018 +0200

    #16 fix typo in docs

commit 2003e7743f
Author: Konstantin Pogorelov <or@pluseq.com>
Date:   Sat Aug 25 12:44:24 2018 +0200

    #16 fix unit test (cluster_metrics/metrics_cluster), cover the error branch

commit 568c87216a
Author: Konstantin Pogorelov <or@pluseq.com>
Date:   Sat Aug 25 12:42:53 2018 +0200

    #16 remove unnecessary check for existance after new, break on error with 500

commit 98be36244e
Author: Konstantin Pogorelov <or@pluseq.com>
Date:   Sat Aug 25 12:40:15 2018 +0200

    #16 make the cluster example runnable

.eslintrc

@@ -1,42 +1,54 @@
 {
-    "env": {
-        "node": true,
-        "es6": true
-    },
+  "parserOptions": {
+    "ecmaVersion": 6,
+    "sourceType": "module"
+  },
 
-    "extends": "eslint:recommended",
+  "globals": {
+    "app": true,
+    "fetch": true
+  },
 
-    "rules": {
-        "no-cond-assign": 0,
-        "no-constant-condition": 0,
-        "no-empty": 0,
-        "no-fallthrough": 0,
-        "no-unused-vars": 1,
-        "no-console": 1,
+  "env": {
+    "node": true,
+    "es6": true
+  },
 
-        "semi": 2,
-        "curly": 2,
-        "consistent-this": [2, "self"],
-        "indent": [ 2, 4, { "SwitchCase": 1 } ],
-        "linebreak-style": [2, "unix"],
-        "no-nested-ternary": 2,
+  "extends": "eslint:recommended",
 
-        "new-parens": 2,
-        "no-dupe-class-members": 2,
-        "require-yield": 2,
-        "arrow-spacing": 1,
-        "no-var": 2,
+  "rules": {
+    "array-bracket-spacing": [2, "never"],
+    "block-scoped-var": 2,
+    "brace-style": [2, "1tbs"],
+    "computed-property-spacing": [2, "never"],
+    "curly": 2,
+    "eol-last": 2,
+    "eqeqeq": [2, "smart"],
+    "max-depth": [1, 3],
+    "new-cap": 1,
+    "no-extend-native": 2,
+    "no-mixed-spaces-and-tabs": 2,
+    "no-trailing-spaces": 1,
+    "no-unused-vars": 1,
+    "no-use-before-define": [2, "nofunc"],
+    "object-curly-spacing": [2, "never"],
+    "quotes": [1, "single", "avoid-escape"],
+    "semi": [2, "always"],
+    "keyword-spacing": [2, {"before": true, "after": true}],
+    "space-unary-ops": 2,
+    "no-console": [1, { allow: ["info", "warn", "error"] }],
 
-        "no-multi-spaces": 1,
-        "space-return-throw-case": 0,
-        "space-infix-ops": [1, {"int32Hint": false}],
-        "brace-style": 1,
-        "space-before-blocks": 1,
-        "operator-linebreak": [1, "before"],
-        "no-unneeded-ternary": 1,
-        "no-lonely-if": 1,
-        "key-spacing": 1,
-        "quotes": [1, "double", "avoid-escape"],
-        "no-trailing-spaces": [1, { "skipBlankLines": true }]
-    }
+    "max-len": [1, 120],
+    "max-statements": [1, 50],
+
+    "consistent-this": [2, "self"],
+    "no-var": 2,
+    "no-dupe-class-members": 2,
+    "operator-linebreak": [1, "before"],
+    "no-unneeded-ternary": [1, {"defaultAssignment": false}],
+    "no-lonely-if": 1,
+    "linebreak-style": [2, "unix"],
+    "no-nested-ternary": 2,
+    "require-yield": 2
+  }
 }

.travis.yml

@@ -1,5 +1,4 @@
 language: node_js
 node_js:
     - "6"
-    - "5"
-    - "4"
+    - "8"

README.md

@@ -2,15 +2,14 @@
 
 # express prometheus bundle
 
-Express middleware with popular prometheus metrics in one bundle. It's also compatible with koa v1 (see below).
+Express middleware with popular prometheus metrics in one bundle. It's also compatible with koa v1 and v2 (see below).
 
 Internally it uses **prom-client**. See: https://github.com/siimon/prom-client
 
 Included metrics:
 
 * `up`: normally is just 1
-* `nodejs_memory_heap_total_bytes` and `nodejs_memory_heap_used_bytes`
-* `http_request_seconds`: http latency histogram labeled with `status_code`
+* `http_request_duration_seconds`: http latency histogram labeled with `status_code`, `method` and `path`
 
 ## Install
 
@@ -18,12 +17,12 @@ Included metrics:
 npm install express-prom-bundle
 ```
 
-## Usage
+## Sample Usage
 
 ```javascript
-const promBundle = require("express-prom-bundle"),
-      metricsMiddleware = promBundle({/* options */ }),
-      app = require("express")();
+const promBundle = require("express-prom-bundle");
+const app = require("express")();
+const metricsMiddleware = promBundle({includeMethod: true});
 
 app.use(metricsMiddleware);
 app.use(/* your middleware */);
@@ -35,7 +34,7 @@ app.listen(3000);
 
 **ALERT!**
 
-The order in wich the routes are registered is important, since
+The order in which the routes are registered is important, since
 **only the routes registered after the express-prom-bundle will be measured**
 
 You can use this to your advantage to bypass some of the routes.
@@ -43,28 +42,88 @@ See the example below.
 
 ## Options
 
- * **prefix**:  prefix added to every metric name
- * **whitelist**, **blacklist**: array of strings or regexp specifying which metrics to include/exclude
- * **buckets**: buckets used for `http_request_seconds` histogram
- * **includeMethod**: include HTTP method (GET, PUT, ...) as a label to `http_request_seconds`
- * **includePath**: include URL path as a label - **EXPERIMENTAL!** (see below)
- * **normalizePath**: boolean or `function(req)` - path normalization for `includePath` option
- * **excludeRoutes**: array of strings or regexp specifying which routes should be skipped for `http_request_seconds` metric. It uses `req.path` as subject when checking
- * **autoregister**: if `/metrics` endpoint should be registered. It is (Default: **true**)
- * **keepDefaultMetrics**: if default metrics provided by **prom-client** should be probed and delivered. (Default: **false**)
+Which labels to include in `http_request_duration_seconds` metric:
 
-### includePath option
+* **includeStatusCode**: HTTP status code (200, 400, 404 etc.), default: **true**
+* **includeMethod**: HTTP method (GET, PUT, ...), default: **false**
+* **includePath**: URL path (see importent details below), default: **false**
+* **customLabels**: an object containing extra labels, e.g. ```{project_name: 'hello_world'}```.
+  Most useful together with **transformLabels** callback, otherwise it's better to use native Prometheus relabeling.
 
-The goal is to have separate latency statistics by URL path, e.g. `/my-app/user/`, `/products/by-category` etc.
+Extra transformation callbacks:
 
-But just taking `req.path` as a label value won't work as IDs are often part of the URL, like `/user/12352/profile`. So what we actually need is a path template. The automatically module tries to figure out what parts of the path are values or IDs, and what is an actual path. The example mentioned before would be normalized to `/user/#val/profile` and that will become the value for the label.
+* **normalizePath**: `function(req)`  or `Array`
+  * if function is provided, then it should generate path value from express `req`
+  * if array is provided, then it should be an array of tuples `[regex, replacement]`. The `regex` can be a string and is automatically converted into JS regex.
+  * ... see more details in the section below
+* **urlValueParser**: options passed when instantiating [url-value-parser](https://github.com/disjunction/url-value-parser).
+  This is the easiest way to customize which parts of the URL should be replaced with "#val".
+  See the [docs](https://github.com/disjunction/url-value-parser) of url-value-parser module for details.
+* **formatStatusCode**: `function(res)` producing final status code from express `res` object, e.g. you can combine `200`, `201` and `204` to just `2xx`.
+* **transformLabels**: `function(labels, req, res)` transforms the **labels** object, e.g. setting dynamic values to **customLabels**
 
-You can override this magical behavior and create define your own function by providing an optional callback **normalizePath**.
+Other options:
+
+* **buckets**: buckets used for `http_request_duration_seconds` histogram
+* **autoregister**: if `/metrics` endpoint should be registered. (Default: **true**)
+* **promClient**: options for promClient startup, e.g. **collectDefaultMetrics**. This option was added
+  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)
+
+### More details on includePath option
+
+Let's say you want to have  latency statistics by URL path,
+e.g. separate metrics for `/my-app/user/`, `/products/by-category` etc.
+
+Just taking `req.path` as a label value won't work as IDs are often part of the URL,
+like `/user/12352/profile`. So what we actually need is a path template.
+The module tries to figure out what parts of the path are values or IDs,
+and what is an actual path. The example mentioned before would be
+normalized to `/user/#val/profile` and that will become the value for the label.
+These conversions are handled by `normalizePath` function.
+
+You can extend this magical behavior by providing
+additional RegExp rules to be performed,
+or override `normalizePath` with your own function.
+
+#### Example 1 (add custom RegExp):
+
+```javascript
+app.use(promBundle({
+  normalizePath: [
+    // collect paths like "/customer/johnbobson" as just one "/custom/#name"
+    ['^/customer/.*', '/customer/#name'],
+
+    // collect paths like "/bobjohnson/order-list" as just one "/#name/order-list"
+    ['^.*/order-list', '/#name/order-list']
+  ],
+  urlValueParser: {
+    minHexLength: 5,
+    extraMasks: [
+      'ORD[0-9]{5,}' // replace strings like ORD1243423, ORD673562 as #val
+    ]
+  }
+}));
+```
+
+#### Example 2 (override normalizePath function):
+
+```javascript
+app.use(promBundle(/* options? */));
+
+// let's reuse the existing one and just add some
+// functionality on top
+const originalNormalize = promBundle.normalizePath;
+promBundle.normalizePath = (req, opts) => {
+  const path = originalNormalize(req, opts);
+  // count all docs as one path, but /docs/login as a separate one
+  return (path.match(/^\/docs/) && !path.match(/^\/login/)) ? '/docs/*' : path;
+};
+```
 
 For more details:
  * [url-value-parser](https://www.npmjs.com/package/url-value-parser) - magic behind automatic path normalization
- * [normalizePath.js](https://github.com/jochen-schweizer/express-prom-bundle/blob/master/src/normalizePath.js) - source code for path processing, for you
-
+ * [normalizePath.js](https://github.com/jochen-schweizer/express-prom-bundle/blob/master/src/normalizePath.js) - source code for path processing
 
 
 ## express example
@@ -72,23 +131,20 @@ For more details:
 setup std. metrics but exclude `up`-metric:
 
 ```javascript
-"use strict";
-
-const express = require("express"),
-      app = express(),
-      promBundle = require("express-prom-bundle");
-
+const express = require("express");
+const app = express();
+const promBundle = require("express-prom-bundle");
 
 // calls to this route will not appear in metrics
 // because it's applied before promBundle
 app.get("/status", (req, res) => res.send("i am healthy"));
 
-app.use(promBundle({
-    prefix: "demo_app:something",
-    excludeRoutes: ["/foo"]
-}));
+// register metrics collection for all routes
+// ... except those starting with /foo
+app.use("/((?!foo))*", promBundle({includePath: true}));
 
-// this call will NOT appear in metrics, because it matches excludeRoutes
+// this call will NOT appear in metrics,
+// because express will skip the metrics middleware
 app.get("/foo", (req, res) => res.send("bar"));
 
 // calls to this route will appear in metrics
@@ -99,26 +155,94 @@ app.listen(3000);
 
 See an [advanced example on github](https://github.com/jochen-schweizer/express-prom-bundle/blob/master/advanced-example.js)
 
-## koa v1 example
+## koa v2 example
 
 ```javascript
-const promBundle = require("express-prom-bundle"),
-      koa = require("koa"),
-      c2k = require("koa-connect"),
-      metricsMiddleware = promBundle({/* options */ });
+const promBundle = require("express-prom-bundle");
+const Koa = require("koa");
+const c2k = require("koa-connect");
+const metricsMiddleware = promBundle({/* options */ });
 
-const app = koa();
+const app = new Koa();
 
 app.use(c2k(metricsMiddleware));
 app.use(/* your middleware */);
 app.listen(3000);
 ```
 
-## Changelog
+## using with cluster
 
- * **1.2.1**
-    * upgrade prom-client to 6.1.2
-    * add options: includeMethod, includePath, keepDefaultMetrics
+You'll need to use an additional **clusterMetrics()** middleware.
+
+In the example below the master process will expose an API with a single endpoint `/metrics`
+which returns an aggregate of all metrics from all the workers.
+
+``` javascript
+const cluster = require('cluster');
+const promBundle = require('./src/index');
+const numCPUs = Math.max(2, require('os').cpus().length);
+const express = require('express');
+
+if (cluster.isMaster) {
+    for (let i = 1; i < numCPUs; i++) {
+        cluster.fork();
+    }
+
+    const metricsApp = express();
+    metricsApp.use('/metrics', promBundle.clusterMetrics());
+    metricsApp.listen(9999);
+
+    console.log('cluster metrics listening on 9999');
+    console.log('call localhost:9999/metrics for aggregated metrics');
+} else {
+    const app = express();
+    app.use(promBundle({
+        autoregister: false, // disable /metrics for single workers
+        includeMethod: true
+    }));
+    app.use((req, res) => res.send(`hello from pid ${process.pid}\n`));
+    app.listen(3000);
+    console.log(`worker ${process.pid} listening on 3000`);
+}
+```
+
+## using with kraken.js
+
+Here is meddleware config sample, which can be used in a standard **kraken.js** application.
+In this case the stats for URI paths and HTTP methods are collected separately,
+while replacing all HEX values starting from 5 characters and all emails in the path as #val.
+
+```json
+{
+  "middleware": {
+    "expressPromBundle": {
+      "route": "/((?!status|favicon.ico|robots.txt))*",
+      "priority": 0,
+      "module": {
+        "name": "express-prom-bundle",
+        "arguments": [
+          {
+            "includeMethod": true,
+            "includePath": true,
+            "buckets": [0.1, 1, 5],
+            "promClient": {
+              "collectDefaultMetrics": {
+                "timeout": 2000
+              }
+            },
+            "urlValueParser": {
+              "minHexLength": 5,
+              "extraMasks": [
+                "^[0-9]+\\.[0-9]+\\.[0-9]+$"
+              ]
+            }
+          }
+        ]
+      }
+    }
+  }
+}
+```
 
 ## License
 

advanced-example.js

@@ -1,45 +1,55 @@
-"use strict";
+'use strict';
 
-const express = require("express");
+const express = require('express');
 const app = express();
-const promBundle = require("express-prom-bundle");
+const promBundle = require('express-prom-bundle');
 
 const bundle = promBundle({
-    prefix: "demo_app:something:",
-    blacklist: [/up/],
-    buckets: [0.1, 0.4, 0.7],
-    includeMethod: true,
-    includePath: true,
-    keepDefaultMetrics: false
+  buckets: [0.1, 0.4, 0.7],
+  includeMethod: true,
+  includePath: true,
+  customLabels: {year: null},
+  transformLabels: labels => Object.assign(labels, {year: new Date().getFullYear()}),
+  promClient: {
+    collectDefaultMetrics: {
+      timeout: 1000
+    }
+  },
+  urlValueParser: {
+    minHexLength: 5,
+    extraMasks: [
+      "^[0-9]+\\.[0-9]+\\.[0-9]+$" // replace dot-separated dates with #val
+    ]
+  },
+  normalizePath: [
+    ['^/foo', '/example'] // replace /foo with /example
+  ]
 });
 
 app.use(bundle);
 
 // native prom-client metric (no prefix)
-const c1 = new bundle.promClient.Counter("c1", "c1 help");
+const c1 = new bundle.promClient.Counter({name: 'c1', help: 'c1 help'});
 c1.inc(10);
 
-// create metric using factory (w/ prefix)
-const c2 = bundle.factory.newCounter("c2", "c2 help");
-c2.inc(20);
-
-app.get("/foo/:id", (req, res) => {
-    setTimeout(() => {
-        res.send("foo response\n");
-    }, 500);
+app.get('/foo/:id', (req, res) => {
+  setTimeout(() => {
+    res.send('foo response\n');
+  }, 500);
 });
-app.delete("/foo/:id", (req, res) => {
-    setTimeout(() => {
-        res.send("foo deleted\n");
-    }, 300);
+app.delete('/foo/:id', (req, res) => {
+  setTimeout(() => {
+    res.send('foo deleted\n');
+  }, 300);
 });
-app.get("/bar", (req, res) => res.send("bar response\n"));
+app.get('/bar', (req, res) => res.send('bar response\n'));
 
 app.listen(3000, () => console.info(  // eslint-disable-line
-  "listening on 3000\n"
-  + "test in shell console\n\n"
-  + "curl localhost:3000/foo/1234\n"
-  + "curl -X DELETE localhost:3000/foo/5432\n"
-  + "curl localhost:3000/bar\n"
-  + "curl localhost:3000/metrics\n"
+  'listening on 3000\n'
+  + 'test in shell console\n\n'
+  + 'curl localhost:3000/foo/1234\n'
+  + 'curl localhost:3000/foo/09.08.2018\n'
+  + 'curl -X DELETE localhost:3000/foo/5432\n'
+  + 'curl localhost:3000/bar\n'
+  + 'curl localhost:3000/metrics\n'
 ));

package.json

@@ -1,37 +1,42 @@
 {
   "name": "express-prom-bundle",
-  "version": "1.2.3",
+  "version": "4.2.1",
   "description": "express middleware with popular prometheus metrics in one bundle",
   "main": "src/index.js",
   "keywords": [
     "prometheus",
     "metrics",
     "express",
-    "bundle"
+    "path",
+    "method"
   ],
   "scripts": {
-    "test": "node_modules/jasme/run.js"
+    "test": "node_modules/jasme/run.js",
+    "coverage": "make coverage"
   },
   "author": "Konstantin Pogorelov <or@pluseq.com>",
   "license": "MIT",
   "dependencies": {
     "on-finished": "^2.3.0",
-    "prom-client": "^6.2.0",
-    "url-value-parser": "^1.0.0"
+    "prom-client": "~11.1.1",
+    "url-value-parser": "^2.0.0"
   },
   "devDependencies": {
-    "coveralls": "^2.11.15",
-    "eslint": "^3.11.1",
-    "express": "^4.14.0",
+    "coveralls": "^3.0.2",
+    "eslint": "^5.3.0",
+    "express": "^4.16.3",
     "istanbul": "^0.4.5",
     "jasme": "^5.2.0",
-    "koa": "^1.2.4",
-    "koa-connect": "^1.0.0",
-    "supertest": "^2.0.1",
+    "koa": "^2.5.2",
+    "koa-connect": "^2.0.0",
+    "supertest": "^3.0.0",
     "supertest-koa-agent": "^0.3.0"
   },
   "repository": {
     "type": "git",
     "url": "https://github.com/jochen-schweizer/express-prom-bundle.git"
+  },
+  "engines": {
+    "node": ">=6.0.0"
   }
 }

spec/PromFactorySpec.js

@@ -1,65 +0,0 @@
-"use strict";
-/* eslint-env jasmine */
-const PromFactory = require("../src/PromFactory");
-
-describe("PromFactory", () => {
-    let factory;
-    beforeEach(() => {
-        factory = new PromFactory();
-    });
-    it("creates Counter", () => {
-        const metric = factory.newCounter(
-            "test1",
-            "help for test1",
-            ["label1", "label2"]
-        );
-        expect(metric.name).toBe("test1");
-        expect(metric.help).toBe("help for test1");
-        expect(metric.labelNames).toEqual(["label1", "label2"]);
-    });
-    it("creates Gauge", () => {
-        const metric = factory.newGauge(
-            "test2",
-            "help for test2",
-            ["label1", "label2"]
-        );
-        expect(metric.name).toBe("test2");
-        expect(metric.help).toBe("help for test2");
-        expect(metric.labelNames).toEqual(["label1", "label2"]);
-    });
-    it("creates Histogram with labels", () => {
-        const metric = factory.newHistogram(
-            "test3",
-            "help for test3",
-            ["label1", "label2"],
-            {buckets: [1, 2, 3]}
-        );
-        expect(metric.name).toBe("test3");
-        expect(metric.help).toBe("help for test3");
-        expect(metric.labelNames).toEqual(["label1", "label2"]);
-        expect(metric.bucketValues).toEqual({"1": 0, "2": 0, "3": 0});
-    });
-    it("creates Summary without labels", () => {
-        const metric = factory.newSummary(
-            "test4",
-            "help for test4",
-            {percentiles: [0.1, 0.5]}
-        );
-        expect(metric.name).toBe("test4");
-        expect(metric.help).toBe("help for test4");
-        expect(metric.percentiles).toEqual([0.1, 0.5]);
-    });
-    it("when regsitered with same name, just return old instance", () => {
-        const metric1 = factory.newSummary(
-            "test4",
-            "help for test4",
-            {percentiles: [0.1, 0.5]}
-        );
-        const metric2 = factory.newSummary(
-            "test4",
-            "help for test4",
-            {percentiles: [0.1, 0.5]}
-        );
-        expect(metric1).toBe(metric2);
-    });
-});

spec/index.spec.js

@@ -0,0 +1,423 @@
+'use strict';
+/* eslint-env jasmine */
+
+const express = require('express');
+const supertest = require('supertest');
+const bundle = require('../');
+const Koa = require('koa');
+const c2k = require('koa-connect');
+const supertestKoa = require('supertest-koa-agent');
+const promClient = require('prom-client');
+const cluster = require('cluster');
+
+describe('index', () => {
+  beforeEach(() => {
+    promClient.register.clear();
+  });
+
+  it('metrics returns up=1', done => {
+    const app = express();
+    const bundled = bundle({
+      whitelist: ['up']
+    });
+    app.use(bundled);
+    app.use('/test', (req, res) => res.send('it worked'));
+
+    const agent = supertest(app);
+    agent.get('/test').end(() => {
+      agent
+        .get('/metrics')
+        .end((err, res) => {
+          expect(res.status).toBe(200);
+          expect(res.text).toMatch(/up\s1/);
+          done();
+        });
+    });
+  });
+
+  it('httpDurationMetricName overrides histogram metric name', done => {
+    const app = express();
+    const bundled = bundle({
+      httpDurationMetricName: 'my_http_duration'
+    });
+    app.use(bundled);
+
+    const agent = supertest(app);
+    agent.get('/metrics')
+      .end((err, res) => {
+        expect(res.text).toMatch(/my_http_duration/m);
+        done();
+      });
+  });
+
+  it('metrics should be attached to /metrics by default', done => {
+    const app = express();
+    const bundled = bundle({
+      whitelist: ['up']
+    });
+    app.use(bundled);
+
+    const agent = supertest(app);
+    agent.get('/metrics')
+      .end((err, res) => {
+        expect(res.status).toBe(200);
+        done();
+      });
+  });
+
+  it('metrics can be attached to /metrics programatically', done => {
+    const app = express();
+    const bundled = bundle({
+      autoregister: false
+    });
+    app.use(bundled.metricsMiddleware);
+    app.use(bundled);
+
+    app.use('/test', (req, res) => res.send('it worked'));
+
+    const agent = supertest(app);
+    agent.get('/metrics')
+      .end((err, res) => {
+        expect(res.status).toBe(200);
+        done();
+      });
+  });
+
+  it('metrics can be filtered using exect match', () => {
+    const instance = bundle({blacklist: ['up']});
+    expect(instance.metrics.up).not.toBeDefined();
+    expect(instance.metrics.http_request_duration_seconds).toBeDefined();
+  });
+  it('metrics can be filtered using regex', () => {
+    const instance = bundle({blacklist: [/http/]});
+    expect(instance.metrics.up).toBeDefined();
+    expect(instance.metrics.http_request_duration_seconds).not.toBeDefined();
+  });
+  it('metrics can be whitelisted', () => {
+    const instance = bundle({whitelist: [/^up$/]});
+    expect(instance.metrics.up).toBeDefined();
+    expect(instance.metrics.nodejs_memory_heap_total_bytes).not.toBeDefined();
+    expect(instance.metrics.http_request_duration_seconds).not.toBeDefined();
+  });
+  it('throws on both white and blacklist', () => {
+    expect(() => {
+      bundle({whitelist: [/up/], blacklist: [/up/]});
+    }).toThrow();
+  });
+  it('returns error 500 on incorrect middleware usage', done => {
+    const app = express();
+    app.use(bundle);
+    supertest(app)
+      .get('/metrics')
+      .end((err, res) => {
+        expect(res.status).toBe(500);
+        done();
+      });
+  });
+  it('http latency gets counted', done => {
+    const app = express();
+    const instance = bundle();
+    app.use(instance);
+    app.use('/test', (req, res) => res.send('it worked'));
+    const agent = supertest(app);
+    agent
+      .get('/test')
+      .end(() => {
+        const metricHashMap = instance.metrics.http_request_duration_seconds.hashMap;
+        expect(metricHashMap['status_code:200']).toBeDefined();
+        const labeled = metricHashMap['status_code:200'];
+        expect(labeled.count).toBe(1);
+
+        agent
+          .get('/metrics')
+          .end((err, res) => {
+            expect(res.status).toBe(200);
+            done();
+          });
+      });
+  });
+
+  it('filters out the excludeRoutes', done => {
+    const app = express();
+    const instance = bundle({
+      excludeRoutes: ['/test']
+    });
+    app.use(instance);
+    app.use('/test', (req, res) => res.send('it worked'));
+    const agent = supertest(app);
+    agent
+      .get('/test')
+      .end(() => {
+        const metricHashMap = instance.metrics.http_request_duration_seconds.hashMap;
+        expect(metricHashMap['status_code:200']).not.toBeDefined();
+
+        agent
+          .get('/metrics')
+          .end((err, res) => {
+            expect(res.status).toBe(200);
+            done();
+          });
+      });
+  });
+
+  it('complains about deprecated options', () => {
+    expect(() => bundle({prefix: 'hello'})).toThrow();
+  });
+
+  it('tolerates includePath, includeMethod, includeCustomLabels', done => {
+    const app = express();
+    const instance = bundle({
+      includePath: true,
+      includeMethod: true,
+      includeCustomLabels: {foo: 'bar'}
+    });
+    app.use(instance);
+    app.use('/test', (req, res) => res.send('it worked'));
+    const agent = supertest(app);
+    agent
+      .get('/test')
+      .end(() => {
+        agent
+          .get('/metrics')
+          .end((err, res) => {
+            expect(res.status).toBe(200);
+            done();
+          });
+      });
+  });
+
+  describe('usage of normalizePath()', () => {
+
+    it('normalizePath can be replaced gloablly', done => {
+      const app = express();
+      const original = bundle.normalizePath;
+      bundle.normalizePath = () => 'dummy';
+      const instance = bundle({
+        includePath: true,
+      });
+      app.use(instance);
+      app.use('/test', (req, res) => res.send('it worked'));
+      const agent = supertest(app);
+      agent
+        .get('/test')
+        .end(() => {
+          agent
+            .get('/metrics')
+            .end((err, res) => {
+              expect(res.status).toBe(200);
+              expect(res.text).toMatch(/"dummy"/m);
+              bundle.normalizePath = original;
+              done();
+            });
+        });
+    });
+
+    it('normalizePath function can be overridden', done => {
+      const app = express();
+      const instance = bundle({
+        includePath: true,
+        normalizePath: req => req.originalUrl + '-suffixed'
+      });
+      app.use(instance);
+      app.use('/test', (req, res) => res.send('it worked'));
+      const agent = supertest(app);
+      agent
+        .get('/test')
+        .end(() => {
+          agent
+            .get('/metrics')
+            .end((err, res) => {
+              expect(res.status).toBe(200);
+              expect(res.text).toMatch(/"\/test-suffixed"/m);
+              done();
+            });
+        });
+    });
+
+    it('normalizePath can be passed as an array of [regex, replacement]', done => {
+      const app = express();
+      const instance = bundle({
+        includePath: true,
+        normalizePath: [
+          ['^/docs/whatever/.*$', '/docs'],
+          [/^\/docs$/, '/mocks']
+        ]
+      });
+      app.use(instance);
+      app.use('/docs/whatever/:andmore', (req, res) => res.send('it worked'));
+      const agent = supertest(app);
+      agent
+        .get('/docs/whatever/unimportant')
+        .end(() => {
+          agent
+            .get('/metrics')
+            .end((err, res) => {
+              expect(res.status).toBe(200);
+              expect(res.text).toMatch(/"\/mocks"/m);
+              done();
+            });
+        });
+    });
+  });
+
+  it('formatStatusCode can be overridden', done => {
+    const app = express();
+    const instance = bundle({
+      formatStatusCode: () => 555
+    });
+    app.use(instance);
+    app.use('/test', (req, res) => res.send('it worked'));
+    const agent = supertest(app);
+    agent
+      .get('/test')
+      .end(() => {
+        agent
+          .get('/metrics')
+          .end((err, res) => {
+            expect(res.status).toBe(200);
+            expect(res.text).toMatch(/555/);
+            done();
+          });
+      });
+  });
+
+  it('includeStatusCode=false removes status_code label from metrics', done => {
+    const app = express();
+    const instance = bundle({
+      includeStatusCode: false
+    });
+    app.use(instance);
+    app.use('/test', (req, res) => res.send('it worked'));
+    const agent = supertest(app);
+    agent
+      .get('/test')
+      .end(() => {
+        agent
+          .get('/metrics')
+          .end((err, res) => {
+            expect(res.status).toBe(200);
+            expect(res.text).not.toMatch(/="200"/);
+            done();
+          });
+      });
+  });
+
+  it('customLabels={foo: "bar"} adds foo="bar" label to metrics', done => {
+    const app = express();
+    const instance = bundle({
+      customLabels: {foo: 'bar'}
+    });
+    app.use(instance);
+    app.use('/test', (req, res) => res.send('it worked'));
+    const agent = supertest(app);
+    agent
+      .get('/test')
+      .end(() => {
+        agent
+          .get('/metrics')
+          .end((err, res) => {
+            expect(res.status).toBe(200);
+            expect(res.text).toMatch(/foo="bar"/);
+            done();
+          });
+      });
+  });
+
+  it('tarnsformLabels can set label values', done => {
+    const app = express();
+    const instance = bundle({
+      includePath: true,
+      customLabels: {foo: 'bar'},
+      transformLabels: labels => {
+        labels.foo = 'baz';
+        labels.path += '/ok';
+      }
+    });
+    app.use(instance);
+    app.use('/test', (req, res) => res.send('it worked'));
+    const agent = supertest(app);
+    agent
+      .get('/test')
+      .end(() => {
+        agent
+          .get('/metrics')
+          .end((err, res) => {
+            expect(res.status).toBe(200);
+            expect(res.text).toMatch(/foo="baz"/);
+            expect(res.text).toMatch(/path="\/test\/ok"/);
+            done();
+          });
+      });
+  });
+
+  it('Koa: metrics returns up=1', done => {
+    const app = new Koa();
+    const bundled = bundle({
+      whitelist: ['up']
+    });
+    app.use(c2k(bundled));
+
+    app.use(function(ctx, next) {
+      return next().then(() => ctx.body = 'it worked');
+    });
+
+    const agent = supertestKoa(app);
+    agent.get('/test').end(() => {
+      agent
+        .get('/metrics')
+        .end((err, res) => {
+          expect(res.status).toBe(200);
+          expect(res.text).toMatch(/^up\s1/m);
+          done();
+        });
+    });
+  });
+
+  it('calls promClient.collectDefaultMetrics', () => {
+    const spy = spyOn(promClient, 'collectDefaultMetrics');
+    bundle({
+      promClient: {
+        collectDefaultMetrics: {
+          timeout: 3000
+        }
+      }
+    });
+    expect(spy).toHaveBeenCalledWith({timeout: 3000});
+  });
+
+  describe('usage of clusterMetrics()', () => {
+    it('clusterMetrics returns 200 even without a cluster', (done) => {
+        const app = express();
+
+        cluster.workers = [];
+
+        app.use('/cluster_metrics', bundle.clusterMetrics());
+        const agent = supertest(app);
+        agent
+          .get('/cluster_metrics')
+          .end((err, res) => {
+            expect(res.status).toBe(200);
+            done();
+          });
+    });
+
+    it('clusterMetrics returns 500 in case of an error', (done) => {
+      const app = express();
+      app.use('/cluster_metrics', bundle.clusterMetrics());
+      const agent = supertest(app);
+
+      // create a fake worker, which would not respond in time
+      cluster.workers = [{send: () => {}}];
+
+      const errorSpy = spyOn(console, 'error'); // mute console.error
+
+      agent
+        .get('/cluster_metrics')
+        .end((err, res) => {
+          expect(res.status).toBe(500);
+          expect(errorSpy).toHaveBeenCalled();
+          done();
+        });
+    }, 6000);
+  });
+});

spec/indexSpec.js

@@ -1,231 +0,0 @@
-"use strict";
-/* eslint-env jasmine */
-
-const express = require("express");
-const supertest = require("supertest");
-const bundle = require("../");
-const koa = require("koa");
-const c2k = require("koa-connect");
-const supertestKoa = require("supertest-koa-agent");
-const promClient = require("prom-client");
-
-// had to reinvent, because getSingleMetric() is still not in npm
-function myGetSingleMetric(name) {
-    let returnMetric;
-    promClient.register.getMetricsAsJSON().forEach(metric => {
-        if (metric.name === name) {
-            returnMetric = metric;
-        }
-    });
-    return returnMetric;
-}
-
-describe("index", () => {
-    beforeEach(() => {
-        promClient.register.clear();
-    });
-
-    it("metrics returns up=1", done => {
-        const app = express();
-        const bundled = bundle({
-            prefix: "hello:",
-            whitelist: ["up"]
-        });
-        app.use(bundled);
-
-        app.use("/test", (req, res) => res.send("it worked"));
-
-        const agent = supertest(app);
-        agent.get("/test").end(() => {
-            agent
-                .get("/metrics")
-                .end((err, res) => {
-                    expect(res.status).toBe(200);
-                    expect(res.text).toMatch(/hello:up\s1/);
-                    done();
-                });
-        });
-    });
-
-    it("metrics should be attached to /metrics by default", done => {
-        const app = express();
-        const bundled = bundle({
-            prefix: "hello:",
-            whitelist: ["up"]
-        });
-        app.use(bundled);
-
-        const agent = supertest(app);
-        agent.get("/metrics")
-            .end((err, res) => {
-                expect(res.status).toBe(200);
-                done();
-            });
-    });
-
-    it("metrics can be attached to /metrics programatically", done => {
-        const app = express();
-        const bundled = bundle({
-            autoregister: false
-        });
-        app.use(bundled.metricsMiddleware);
-        app.use(bundled);
-
-        app.use("/test", (req, res) => res.send("it worked"));
-
-        const agent = supertest(app);
-        agent.get("/metrics")
-            .end((err, res) => {
-                expect(res.status).toBe(200);
-                done();
-            });
-    });
-
-    it("metrics can be filtered using exect match", () => {
-        const instance = bundle({blacklist: ["up"]});
-        expect(instance.metrics.up).not.toBeDefined();
-        expect(instance.metrics.nodejs_memory_heap_total_bytes).toBeDefined();
-    });
-    it("metrics can be filtered using regex", () => {
-        const instance = bundle({blacklist: [/memory/]});
-        expect(instance.metrics.up).toBeDefined();
-        expect(instance.metrics.nodejs_memory_heap_total_bytes).not.toBeDefined();
-    });
-    it("metrics can be whitelisted", () => {
-        const instance = bundle({whitelist: [/^up$/]});
-        expect(instance.metrics.up).toBeDefined();
-        expect(instance.metrics.nodejs_memory_heap_total_bytes).not.toBeDefined();
-        expect(instance.metrics.http_request_seconds).not.toBeDefined();
-    });
-    it("throws on both white and blacklist", () => {
-        expect(() => {
-            bundle({whitelist: [/up/], blacklist: [/up/]});
-        }).toThrow();
-    });
-    it("returns error 500 on incorrect middleware usage", done => {
-        const app = express();
-        app.use(bundle);
-        supertest(app)
-            .get("/metrics")
-            .end((err, res) => {
-                expect(res.status).toBe(500);
-                done();
-            });
-    });
-    it("http latency gets counted", done => {
-        const app = express();
-        const instance = bundle();
-        app.use(instance);
-        app.use("/test", (req, res) => res.send("it worked"));
-        const agent = supertest(app);
-        agent
-            .get("/test")
-            .end(() => {
-                const metricHashMap = instance.metrics.http_request_seconds.hashMap;
-                expect(metricHashMap["status_code:200"]).toBeDefined();
-                const labeled = metricHashMap["status_code:200"];
-                expect(labeled.count).toBe(1);
-
-                agent
-                    .get("/metrics")
-                    .end((err, res) => {
-                        expect(res.status).toBe(200);
-                        done();
-                    });
-            });
-    });
-    it("filters out the excludeRoutes", done => {
-        const app = express();
-        const instance = bundle({
-            excludeRoutes: ["/test"]
-        });
-        app.use(instance);
-        app.use("/test", (req, res) => res.send("it worked"));
-        const agent = supertest(app);
-        agent
-            .get("/test")
-            .end(() => {
-                const metricHashMap = instance.metrics.http_request_seconds.hashMap;
-                expect(metricHashMap["status_code:200"]).not.toBeDefined();
-
-                agent
-                    .get("/metrics")
-                    .end((err, res) => {
-                        expect(res.status).toBe(200);
-                        done();
-                    });
-            });
-    });
-
-    describe("initial metrics removal", () => {
-        it("removes unexpected metrics on start with no prefix", () => {
-            new promClient.Counter("foo", "bar");
-            expect(myGetSingleMetric("foo")).toBeDefined();
-            bundle();
-            expect(myGetSingleMetric("foo")).not.toBeDefined();
-        });
-
-        it("removes unexpected metrics on start with a prefix", () => {
-            new promClient.Counter("foo", "bar");
-            expect(myGetSingleMetric("foo")).toBeDefined();
-            bundle({prefix: "some_test_"});
-            expect(myGetSingleMetric("foo")).not.toBeDefined();
-        });
-
-        it("doesnt remove metrics with matched prefix", () => {
-            new promClient.Counter("some_test_foo", "bar");
-            expect(myGetSingleMetric("some_test_foo")).toBeDefined();
-            bundle({prefix: "some_test_"});
-            expect(myGetSingleMetric("some_test_foo")).toBeDefined();
-        });
-    });
-
-    it("tolerates includePath, includeMethod and keepDefaultMetrics", done => {
-        const app = express();
-        const instance = bundle({
-            includePath: true,
-            includeMethod: true,
-            keepDefaultMetrics: true
-        });
-        app.use(instance);
-        app.use("/test", (req, res) => res.send("it worked"));
-        const agent = supertest(app);
-        agent
-            .get("/test")
-            .end(() => {
-                agent
-                    .get("/metrics")
-                    .end((err, res) => {
-                        expect(res.status).toBe(200);
-                        done();
-                    });
-            });
-    });
-
-    it("Koa: metrics returns up=1", done => {
-        const app = koa();
-        const bundled = bundle({
-            prefix: "hello:",
-            whitelist: ["up"]
-        });
-        app.use(c2k(bundled));
-
-        app.use(function*(next) {
-            if (this.path !== "test") {
-                return yield next;
-            }
-            this.body = "it worked";
-        });
-
-        const agent = supertestKoa(app);
-        agent.get("/test").end(() => {
-            agent
-                .get("/metrics")
-                .end((err, res) => {
-                    expect(res.status).toBe(200);
-                    expect(res.text).toMatch(/hello:up\s1/);
-                    done();
-                });
-        });
-    });
-});

spec/normalizePath.spec.js

@@ -0,0 +1,31 @@
+'use strict';
+/* eslint-env jasmine */
+
+const normalizePath = require('../src/normalizePath');
+
+describe('normalizePath', () => {
+  it('uses UrlValueParser by default', () => {
+    expect(normalizePath({url: '/a/12345'}))
+      .toBe('/a/#val');
+  });
+
+  it('uses normalizePath option', () => {
+    const url = '/hello/world/i/am/finally/free!!!';
+    const result = normalizePath({url}, {
+      normalizePath: [
+        ['/hello','/goodbye'],
+        ['[^/]+$','happy'],
+      ]
+    });
+    expect(result).toBe('/goodbye/world/i/am/finally/happy');
+  });
+
+  it('throws error is bad tuples provided as normalizePath', () => {
+    const subject = () => normalizePath({url: '/test'}, {
+      normalizePath: [
+        ['/hello','/goodbye', 'test']
+      ]
+    });
+    expect(subject).toThrow();
+  });
+});

spec/normalizePathSpec.js

@@ -1,28 +0,0 @@
-"use strict";
-/* eslint-env jasmine */
-
-const normalizePath = require("../src/normalizePath");
-
-describe("normalizePath", () => {
-    it("returns original if disabled in opts", () => {
-        expect(
-          normalizePath({originalUrl: "/a/12345"}, {normalizePath: false})
-        ).toBe("/a/12345");
-    });
-
-    it("returns run callback if configured", () => {
-        expect(
-            normalizePath(
-                {originalUrl: "/a/12345"},
-                {
-                    normalizePath: req => req.originalUrl + "-ok"
-                }
-            )
-        ).toBe("/a/12345-ok");
-    });
-
-    it("uses UrlValueParser by default", () => {
-        expect(normalizePath({originalUrl: "/a/12345"}))
-            .toBe("/a/#val");
-    });
-});

spec/normalizeStatusCode.spec.js

@@ -0,0 +1,12 @@
+'use strict';
+/* eslint-env jasmine */
+
+const normalizeStatusCode = require('../src/normalizeStatusCode');
+
+describe('normalizeStatusCode', () => {
+  it('returns run callback if configured', () => {
+    expect(
+      normalizeStatusCode({status_code: 500})
+    ).toBe(500);
+  });
+});

src/PromFactory.js

@@ -1,46 +0,0 @@
-"use strict";
-
-module.exports = class {
-    constructor(opts) {
-        this.opts = opts || {};
-        this.promClient = this.opts.promClient || require("prom-client");
-    }
-
-    makeRealName(name) {
-        return (this.opts.prefix || "") + name;
-    }
-
-    makeMetric(TheClass, args) {
-        // convert pseudo-array
-        const applyParams = Array.prototype.slice.call(args);
-        const name = applyParams[0];
-        const realName = this.makeRealName(name);
-
-        const existing = this.promClient.register.getSingleMetric(realName);
-        if (existing) {
-            return existing;
-        }
-
-        applyParams[0] = realName;
-        applyParams.unshift(null); // add some dummy context for apply
-
-        // call constructor with variable params
-        return new (Function.prototype.bind.apply(TheClass, applyParams)); // eslint-disable-line
-    }
-
-    newCounter() {
-        return this.makeMetric(this.promClient.Counter, arguments);
-    }
-
-    newGauge() {
-        return this.makeMetric(this.promClient.Gauge, arguments);
-    }
-
-    newHistogram() {
-        return this.makeMetric(this.promClient.Histogram, arguments);
-    }
-
-    newSummary() {
-        return this.makeMetric(this.promClient.Summary, arguments);
-    }
-};

src/index.js

@@ -1,165 +1,186 @@
-"use strict";
-
-const PromFactory = require("./PromFactory");
-const onFinished = require("on-finished");
-const url = require("url");
-const promClient = require("prom-client");
-const normalizePath = require("./normalizePath");
+'use strict';
+const onFinished = require('on-finished');
+const promClient = require('prom-client');
+const normalizePath = require('./normalizePath');
+const normalizeStatusCode = require('./normalizeStatusCode');
 
 function matchVsRegExps(element, regexps) {
-    for (let regexp of regexps) {
-        if (regexp instanceof RegExp) {
-            if (element.match(regexp)) {
-                return true;
-            }
-        } else if (element == regexp) {
-            return true;
-        }
+  for (let regexp of regexps) {
+    if (regexp instanceof RegExp) {
+      if (element.match(regexp)) {
+        return true;
+      }
+    } else if (element === regexp) {
+      return true;
     }
-    return false;
+  }
+  return false;
 }
 
 function filterArrayByRegExps(array, regexps) {
-    return array.filter(element => {
-        return matchVsRegExps(element, regexps);
-    });
+  return array.filter(element => {
+    return matchVsRegExps(element, regexps);
+  });
 }
 
 function prepareMetricNames(opts, metricTemplates) {
-    const names = Object.keys(metricTemplates);
-    if (opts.whitelist) {
-        if (opts.blacklist) {
-            throw new Error("you cannot have whitelist and blacklist at the same time");
-        }
-        return filterArrayByRegExps(names, opts.whitelist);
-    }
+  const names = Object.keys(metricTemplates);
+  if (opts.whitelist) {
     if (opts.blacklist) {
-        const blacklisted = filterArrayByRegExps(names, opts.blacklist);
-        return names.filter(name => blacklisted.indexOf(name) === -1);
+      throw new Error('you cannot have whitelist and blacklist at the same time');
     }
-    return names;
+    return filterArrayByRegExps(names, opts.whitelist);
+  }
+  if (opts.blacklist) {
+    const blacklisted = filterArrayByRegExps(names, opts.blacklist);
+    return names.filter(name => blacklisted.indexOf(name) === -1);
+  }
+  return names;
+}
+
+function clusterMetrics() {
+    const aggregatorRegistry = new promClient.AggregatorRegistry();
+
+    const metricsMiddleware = function(req, res, next) {
+      aggregatorRegistry.clusterMetrics((err, clusterMetrics) => {
+        if (err) {
+            console.error(err);
+            return res.sendStatus(500);
+        }
+        res.set('Content-Type', aggregatorRegistry.contentType);
+        res.send(clusterMetrics);
+      });
+    };
+
+    return metricsMiddleware;
 }
 
 function main(opts) {
-    opts = Object.assign({ autoregister: true }, opts || {} );
-    if (arguments[2] && arguments[1] && arguments[1].send) {
-        arguments[1].status(500)
-            .send("<h1>500 Error</h1>\n"
-                + "<p>Unexpected 3rd param in express-prom-bundle.\n"
-                + "<p>Did you just put express-prom-bundle into app.use "
-                + "without calling it as a function first?");
-        return;
+  opts = Object.assign(
+    {
+      autoregister: true,
+      includeStatusCode: true,
+      normalizePath: main.normalizePath,
+      formatStatusCode: main.normalizeStatusCode,
+      promClient: {}
+    },
+    opts
+  );
+  if (arguments[2] && arguments[1] && arguments[1].send) {
+    arguments[1].status(500)
+      .send('<h1>500 Error</h1>\n'
+        + '<p>Unexpected 3rd param in express-prom-bundle.\n'
+        + '<p>Did you just put express-prom-bundle into app.use '
+        + 'without calling it as a function first?');
+    return;
+  }
+
+  if (opts.prefix || opts.keepDefaultMetrics !== undefined) {
+    throw new Error(
+      'express-prom-bundle detected obsolete options:'
+      + 'prefix and/or keepDefaultMetrics. '
+      + 'Please refer to oficial docs. '
+      + 'Most likely you upgraded the module without necessary code changes'
+    );
+  }
+
+  if (opts.promClient.collectDefaultMetrics) {
+    promClient.collectDefaultMetrics(opts.promClient.collectDefaultMetrics);
+  }
+
+  const httpMetricName = opts.httpDurationMetricName || 'http_request_duration_seconds';
+
+  const metricTemplates = {
+    'up': () => new promClient.Gauge({
+      name: 'up',
+      help: '1 = up, 0 = not up'
+    }),
+    [httpMetricName]: () => {
+      const labels = ['status_code'];
+      if (opts.includeMethod) {
+        labels.push('method');
+      }
+      if (opts.includePath) {
+        labels.push('path');
+      }
+      if (opts.customLabels){
+        labels.push.apply(labels, Object.keys(opts.customLabels));
+      }
+      const metric = new promClient.Histogram({
+        name: httpMetricName,
+        help: 'duration histogram of http responses labeled with: ' + labels.join(', '),
+        labelNames: labels,
+        buckets: opts.buckets || [0.003, 0.03, 0.1, 0.3, 1.5, 10]
+      });
+      return metric;
+    }
+  };
+
+  const metrics = {};
+  const names = prepareMetricNames(opts, metricTemplates);
+
+  for (let name of names) {
+    metrics[name] = metricTemplates[name]();
+  }
+
+  if (metrics.up) {
+    metrics.up.set(1);
+  }
+
+  const metricsMiddleware = function(req, res) {
+    res.writeHead(200, {'Content-Type': 'text/plain'});
+    res.end(promClient.register.metrics());
+  };
+
+  const middleware = function (req, res, next) {
+    const path = req.originalUrl || req.url; // originalUrl gets lost in koa-connect?
+    let labels;
+
+    if (opts.autoregister && path.match(/^\/metrics\/?$/)) {
+        return metricsMiddleware(req, res);
     }
 
-    // this is a really messy hack but needed for compatibility with v1
-    // will be completely removed in v2
-    if (!opts.keepDefaultMetrics) {
-        const metrics = promClient.register.getMetricsAsJSON();
-        clearInterval(promClient.defaultMetrics());
-        metrics.forEach(metric => {
-            if (!opts.prefix || metric.name.substr(0, opts.prefix.length) != opts.prefix) {
-                promClient.register.removeSingleMetric(metric.name);
-            }
-        });
+    if (opts.excludeRoutes && matchVsRegExps(path, opts.excludeRoutes)) {
+      return next();
     }
 
-    const factory = new PromFactory(opts);
-
-    const metricTemplates = {
-        "up": () => factory.newGauge(
-            "up",
-            "1 = up, 0 = not up"
-        ),
-        "nodejs_memory_heap_total_bytes": () => factory.newGauge(
-            "nodejs_memory_heap_total_bytes",
-            "value of process.memoryUsage().heapTotal"
-        ),
-        "nodejs_memory_heap_used_bytes": () => factory.newGauge(
-            "nodejs_memory_heap_used_bytes",
-            "value of process.memoryUsage().heapUsed"
-        ),
-        "http_request_seconds": () => {
-            const labels = ["status_code"];
-            if (opts.includeMethod) {
-                labels.push("method");
-            }
-            if (opts.includePath) {
-                labels.push("path");
-            }
-            const metric = factory.newHistogram(
-                "http_request_seconds",
-                "number of http responses labeled with status code",
-                labels,
-                {
-                    buckets: opts.buckets || [0.003, 0.03, 0.1, 0.3, 1.5, 10]
-                }
-            );
-            return metric;
+    if (metrics[httpMetricName]) {
+      labels = {};
+      let timer = metrics[httpMetricName].startTimer(labels);
+      onFinished(res, () => {
+        if (opts.includeStatusCode) {
+          labels.status_code = opts.formatStatusCode(res, opts);
         }
-    };
-
-    const metrics = {};
-    const names = prepareMetricNames(opts, metricTemplates);
-
-    for (let name of names) {
-        metrics[name] = metricTemplates[name]();
+        if (opts.includeMethod) {
+          labels.method = req.method;
+        }
+        if (opts.includePath) {
+          labels.path = typeof opts.normalizePath == 'function'
+            ? opts.normalizePath(req, opts)
+            : main.normalizePath(req, opts);
+        }
+        if (opts.customLabels) {
+          Object.assign(labels, opts.customLabels);
+        }
+        if (opts.transformLabels) {
+          opts.transformLabels(labels, req, res);
+        }
+        timer();
+      });
     }
 
-    if (metrics.up) {
-        metrics.up.set(1);
-    }
+    next();
+  };
 
-    const metricsMiddleware = function(req,res) {
-        let memoryUsage = process.memoryUsage();
-        if (metrics["nodejs_memory_heap_total_bytes"]) {
-            metrics["nodejs_memory_heap_total_bytes"].set(memoryUsage.heapTotal);
-        }
-        if (metrics["nodejs_memory_heap_used_bytes"]) {
-            metrics["nodejs_memory_heap_used_bytes"].set(memoryUsage.heapUsed);
-        }
-
-        res.writeHead(200, {"Content-Type": "text/plain"});
-        res.end(factory.promClient.register.metrics());
-    };
-
-    const middleware = function (req, res, next) {
-
-        const path = req.path || url.parse(req.url).pathname;
-        let labels;
-
-        if (opts.autoregister && path == "/metrics") {
-            return metricsMiddleware(req,res);
-        }
-
-        if (opts.excludeRoutes && matchVsRegExps(path, opts.excludeRoutes)) {
-            return next();
-        }
-
-        if (metrics["http_request_seconds"]) {
-            labels = {"status_code": 0};
-            let timer = metrics["http_request_seconds"].startTimer(labels);
-            onFinished(res, () => {
-                labels.status_code = res.statusCode;
-                if (opts.includeMethod) {
-                    labels.method = req.method;
-                }
-                if (opts.includePath) {
-                    labels.path = normalizePath(req, opts);
-                }
-                timer();
-            });
-        }
-
-        next();
-    };
-
-    middleware.factory = factory;
-    middleware.metricTemplates = metricTemplates;
-    middleware.metrics = metrics;
-    middleware.promClient = factory.promClient;
-    middleware.metricsMiddleware = metricsMiddleware;
-    return middleware;
+  middleware.metricTemplates = metricTemplates;
+  middleware.metrics = metrics;
+  middleware.promClient = promClient;
+  middleware.metricsMiddleware = metricsMiddleware;
+  return middleware;
 }
 
 main.promClient = promClient;
+main.normalizePath = normalizePath;
+main.normalizeStatusCode = normalizeStatusCode;
+main.clusterMetrics = clusterMetrics;
 module.exports = main;

src/normalizePath.js

@@ -1,26 +1,30 @@
-"use strict";
+'use strict';
 
-const UrlValueParser = require("url-value-parser");
-const url = require("url");
+const UrlValueParser = require('url-value-parser');
+const url = require('url');
+
+// ATTENTION! urlValueParser is a singleton!
 let urlValueParser;
 
 module.exports = function(req, opts) {
-    opts = opts || {};
+  // originalUrl is taken, because url and path can be changed
+  // by middlewares such as 'router'. Note: this function is called onFinish
+  /// i.e. always in the tail of the middleware chain
+  let path = url.parse(req.originalUrl || req.url).pathname;
 
-    // originalUrl is taken, because url and path can be changed
-    // by middlewares such as "router". Note: this function is called onFinish
-    /// i.e. always in the tail of the middleware chain
-    const path = url.parse(req.originalUrl).pathname;
+  const normalizePath = opts && opts.normalizePath;
+  if (Array.isArray(normalizePath)) {
+    for (const tuple of normalizePath) {
+      if (!Array.isArray(tuple) || tuple.length !== 2) {
+        throw new Error('Bad tuple provided in normalizePath option, expected: [regex, replacement]');
+      }
+      const regex = typeof tuple[0] === 'string' ? RegExp(tuple[0]) : tuple[0];
+      path = path.replace(regex, tuple[1]);
+    }
+  }
 
-    if (opts.normalizePath !== undefined && !opts.normalizePath) {
-        return path;
-    }
-    if (typeof opts.normalizePath === "function") {
-        return opts.normalizePath(req, opts);
-    }
-
-    if (!urlValueParser) {
-        urlValueParser = new UrlValueParser();
-    }
-    return urlValueParser.replacePathValues(path);
+  if (!urlValueParser) {
+    urlValueParser = new UrlValueParser(opts && opts.urlValueParser);
+  }
+  return urlValueParser.replacePathValues(path);
 };

src/normalizeStatusCode.js

@@ -0,0 +1,5 @@
+'use strict';
+
+module.exports = function(res) {
+  return res.status_code || res.statusCode;
+};