Added custom metrics

README.md

@@ -20,6 +20,17 @@ Before your Routes:
 And to enable the *_metrics*-Endpoint:  
 `router.get('/_metrics', metrics.endpoint)`  
 
+To Add your own custom Metrics:
+`metrics.addCustomMetric({
+      name: 'test',
+      help: 'Some Test Metric',
+      labelNames: ['tester']
+    })`
+
+then you may increase or decrease the value at any given point:
+`this.metrics.incCustomMetric('test', 'tester', 'called_bar')`
+`this.metrics.decCustomMetric('test', 'tester', 'called_bar')`
+
 ### Options
 
 The Following Options may be used to configure the behaviour.

examples/src/app.ts

@@ -25,6 +25,12 @@ class App {
       disableDefaultMetrics: false
     })
 
+    this.metrics.addCustomMetric({
+      name: 'test',
+      help: 'Some Test Metric',
+      labelNames: ['tester']
+    })
+
     this.router.use(this.metrics.collect)
 
     this.router.get('/favicon.ico', (req, res) => res.status(204)) // No Favicon here
@@ -33,6 +39,7 @@ class App {
       res.status(200).send('foo')
     })
     this.router.get('/bar', (req:express.Request, res:express.Response) => {
+      this.metrics.incCustomMetric('test', 'tester', 'called_bar')
       res.status(200).send('bar')
     })
     this.router.get('/404', (req:express.Request, res:express.Response) => {

package.json

@@ -25,31 +25,31 @@
     "prom-client": "^12.0.0"
   },
   "devDependencies": {
-    "@stryker-mutator/core": "^3.1.0",
-    "@stryker-mutator/jest-runner": "^3.1.0",
-    "@stryker-mutator/typescript": "^3.1.0",
-    "@types/express": "^4.17.4",
-    "@types/jest": "^25.1.4",
-    "@types/node": "^13.9.1",
+    "@stryker-mutator/core": "^3.2.4",
+    "@stryker-mutator/jest-runner": "^3.2.4",
+    "@stryker-mutator/typescript": "^3.2.4",
+    "@types/express": "^4.17.6",
+    "@types/jest": "^26.0.0",
+    "@types/node": "^14.0.13",
     "@types/superagent": "^4.1.7",
-    "@types/supertest": "^2.0.8",
-    "@typescript-eslint/eslint-plugin": "^2.24.0",
-    "eslint": "^6.8.0",
-    "eslint-config-standard-with-typescript": "^15.0.0",
-    "eslint-plugin-import": "^2.20.1",
-    "eslint-plugin-node": "^11.0.0",
+    "@types/supertest": "^2.0.9",
+    "@typescript-eslint/eslint-plugin": "^3.2.0",
+    "eslint": "^7.2.0",
+    "eslint-config-standard-with-typescript": "^18.0.2",
+    "eslint-plugin-import": "^2.21.2",
+    "eslint-plugin-node": "^11.1.0",
     "eslint-plugin-promise": "^4.2.1",
     "eslint-plugin-security": "^1.4.0",
     "eslint-plugin-standard": "^4.0.1",
-    "eslint-plugin-tsdoc": "^0.2.3",
-    "husky": "^4.2.3",
-    "jest": "^25.1.0",
+    "eslint-plugin-tsdoc": "^0.2.5",
+    "husky": "^4.2.5",
+    "jest": "^26.0.1",
     "jest-html-reporters": "^1.2.1",
     "mock-express-request": "^0.2.2",
-    "standard": "^14.3.3",
+    "standard": "^14.3.4",
     "supertest": "^4.0.2",
-    "ts-jest": "^25.2.1",
-    "typescript": "^3.8.3"
+    "ts-jest": "^26.1.0",
+    "typescript": "^3.9.5"
   },
   "husky": {
     "hooks": {

src/index.ts

@@ -8,6 +8,12 @@ export interface Options {
   disableDefaultMetrics: boolean
 }
 
+export interface CustomMetric {
+  name: string
+  help: string
+  labelNames: string[]
+}
+
 export class Metrics {
   public readonly _ignore: string[]
   public readonly _disableRouteCounter: boolean
@@ -21,8 +27,11 @@ export class Metrics {
   public readonly _numOfRequests: any
   public readonly _numOfErrors: any
 
+  public readonly _customMetrics: any
+
   constructor (options: Partial<Options> = {}) {
     this._client = require('prom-client')
+    this._customMetrics = {}
 
     if (typeof options.ignore !== 'undefined') {
       this._ignore = options.ignore
@@ -78,6 +87,25 @@ export class Metrics {
     }
   }
 
+  public addCustomMetric = (options: CustomMetric): void => {
+    this._customMetrics[options.name] = new this._client.Gauge({
+      name: options.name,
+      help: options.help,
+      labelNames: options.labelNames
+    })
+  }
+
+  public incCustomMetric = (name: string, label: string, value: string): void => {
+    const inc: any = {}
+    inc[label] = value
+    this._customMetrics[name].inc(inc)
+  }
+  public decCustomMetric = (name: string, label: string, value: string): void => {
+    const dec: any = {}
+    dec[label] = value
+    this._customMetrics[name].dec(dec)
+  }
+
   public collect = (req: express.Request, res: express.Response, next: express.NextFunction): void => {
     res.locals.startEpoch = Date.now()
     res.on('finish', () => {