Fetch Prometheus

This is a wrapper for 'node-fetch' module that submits metrics for all executed requests to Prometheus service.

Install

npm i --save fetch-prometheus

Example

Basic example:

const fetch = require('fetch-prometheus')(); //will use default node-fetch module to fetch data

fetch('https://api.ipify.org?format=json');

Custom fetch module usage:

const fetchRetry = require('fetch-retry');
const fetch      = require('fetch-prometheus')(fetchRetry); //will use custom 'fetch-retry' module to fetch Data.

fetch('https://api.ipify.org?format=json');

Custom publishURL example:

fetch('https://api.ipify.org?format=json', {
  publishURL: 'get_ip_request' //instead of publishing 'https://api.ipify.org?format=json' to prometheus it will publish metrics for this request under 'get_ip_request' request name. It should improve readability of metrics. 
});

Example of submitted metrics at Grafana (dashboard for Prometheus):

Requests per minute chart:

Request execution time in seconds:

Options added to default node-fetch options.

| Name | Description | | :-: | :- | | publishURL |Customize name of request when publishing metrics to prometheus. Designed to increase readability of metrics at Prometheus |

prom-client integration:

This module only submits metrics to Prometheus by using prom-client module. Make sure you expose metrics as an endpoint so Prometheus can collect them, or make sure you push them by using PushGateway.

Example of exposing prom-client metrics assuming you use Express.js:

const Prometheus = require('prom-client');
const express = require('express');

app.get('prometheus-metrics', (req, res) => {
  res.set('Content-Type', Prometheus.register.contentType);
  res.end(Prometheus.register.metrics());
});

Example of pushing metrics to Prometheus by using PushGateway:

const {Pushgateway} = require('prom-client');
const gateway  = new Pushgateway('http://localhost:9091');

const push = () => gateway.push({jobName: 'test_job'}, err => {
  if (err) {
    console.error(`Error on pushing metrics to Prometheus. Reason: ${err.message}`);
  } else {
    console.log('Metrics pushed to Prometheus');
  }
});

setInterval(() => {
  push();
}, 10000);

For more detailed information visit prom-client page.

Metrics exposed

• http_requests_total: Counter for total requests received, has labels url, method, status, generalized_status
• http_request_duration_seconds: Duration of HTTP requests in seconds, has labels url, method, status, generalized_status

Label generalized_status is normalized to status code family groups, like 2XX or 4XX

Label url may be customized by passing custom publishURL in options