Metrics Controller for NodeJS based APIs

This is a simplified wrapper in hopes of standardizing the metrics reported for our NodeJS based services to Prometheus

Kuberentes Config

Annotate the Service Defintion

Assuming the api/service base path is at: /api

apiVersion: v1
kind: Service
metadata:
  name: example-api
  labels:
    app: example
    environment: dev
    tier: api
  annotations:
    prometheus.io/path: "/api/metrics"
    prometheus.io/scrape: "true"

NOTE: If your api does not have a base path and the metrics will be available at /metrics then you can eliminate the prometheus.io/path annotation

This is the best documentation (at time of writing): Prometheus Config Docs

swagger.yaml Config

  /metrics:
    x-swagger-router-controller: metrics
    get:
      description: Returns api metrics for Prometheus
      operationId: getMetrics
      produces:
       - text/plain
      responses:
        "200":
          description: success
          schema:
            type: string

API Setup

Default Metrics

Default metrics will be collected unless you set the autoStart option to false. Default metrics come from prom-client library

Per Request Metrics

Inorder to collect per-request metrics, you must add the middleware to your app / server. The RPM class exposes this via the requestMiddleware method.

Example Setup

app.js

const restify = require('restify');
const Metrics = require('nodejs-prometheus-metrics');
const app = restify.createServer();

const metrics = new Metrics({
  prefix: 'my_cool_api_',
  requestObjPath: 'swagger.apiPath'
});

app.use(metrics.requestMiddleware);

metricsController.js

const Metrics = require('nodejs-prometheus-metrics');
const metrics = new Metrics();

function requestController(req, res, next) {
	metrics.getMetrics();
	return next();
}

module.exports = requestController

Options

| Name (type) | Default | Description | | --- | --- | --- | | autoStart (bool) | true | Start Collection default metrics. If you set this value to false you must call start to collect default metricss | | requestObjPath (string / function) | 'path' | Path in the request object that should be used for determining the path of the request. ex. With swagger it obfuscates the path request therefore swagger.apiPath can be used | | metricsEndpoint (string) | '/metrics' | if your api uses a different path for metrics. ex. /api/metrics | | promTimeout (int) | 5000 | Time in MS between metric collections |