configured-prometheus-client

A small wrapper around the Prometheus client to allow configuration from JSON configuration or hydration.

You can create metrics "upfront":

import PrometheusClient from '@gasbuddy/configured-prometheus-client';

const client = new PrometheusClient({}, {
    histograms: {
      TestHisto: {
        help: 'Test Histogram',
        labels: ['foo', 'baz'],
        buckets: [0.1, 0.2, 1],
      },
    },
    counters: {
      TestCount: {
        help: 'Test Counter',
      },
    },
    gauges: {
      TestGauge: {
        help: 'Test Gauge',
      },
    },
    summaries: {
      TestSum: {
        help: 'Test Summary',
      },
    },
  });

// Increment the counter by 5
client.counters.TestCount.inc(5);

Also, since most things you want to time are some sort of asynchronous operation, the client provides a "Promise timer" method:

async function aPromise(value) {
  await Promise.delay(1);
  return value;
}

const rz = await client.promiseTimer('TestHisto')
  .label({ foo: 'bar' })
  .labelSuccess(result => ({ baz: result }))
  .execute(aPromise('beep'));
// rz is now the result of the promise

The foo:bar label will be applied on the call to startTimer, and the baz:beep label will be applied when the timer ends assuming the promise resolves rather than rejects (use labelError for that case). Each of the label functions accepts either a function (so you can examine the result of the promise) or a literal object that just gets added to the labels.

(Note that literal labels applied with .label() will always be applied when the timer STARTS, all others will be applied in order after it resolves or rejects).