Adding JSON metrics route option

[Sunny-fr]

Hello there,

The suffix for the metrics path on express is hard coded, it would be nice to have it "customizable" :

if (routeUrl === `${this.setupOptions.metricsRoute}.json`) {
  debug('Request to /metrics endpoint');
  return res.json(Prometheus.register.getMetricsAsJSON());
}

prometheus-api-metrics/src/express-middleware.js

Line 101 in 441cb48

if (routeUrl === `${this.setupOptions.metricsRoute}.json`) {

Thank you

[kobik]

Hi @Sunny-fr,

Thanks for your PR!

Can you please share your use-case?

[Sunny-fr]

Yes of course.
In my company we use the same pattern for our grafana configs and metrics must look like this :

{APP}/metrics/json instead of {APP}/metrics.json

So in my code it looks like this :

const apiMetrics = require('prometheus-api-metrics')
const middleWare = function (app, router, config) {
  app.use(
    apiMetrics({
      metricsPath: config.publicPath + '/metrics',
      metricsJsonSuffix: '/json',
    })
  )
}

it's not perfect, i think the better way is to provide a full path to the json route.
example :

if (this.setupOptions.metricsJsonRoute !== '' ? this.setupOptions.metricsJsonRoute : routeUrl === `${this.setupOptions.metricsRoute}.json`) {
  debug('Request to /metrics endpoint');
  return res.json(Prometheus.register.getMetricsAsJSON());
}

But I tried to keep it simple and understandable :)

[kobik]

i actually prefer your second alternative.

IMO, it's less confusing and more flexible.

[Sunny-fr]

Ok thanks !
Here it is :

        setupOptions.metricsRoute = metricsPath || '/metrics';
        setupOptions.metricsJsonRoute = metricsJsonPath || `${setupOptions.metricsRoute}.json`;

https://github.com/Sunny-fr/prometheus-api-metrics/blob/fcb3ae8fc5e64a4bd1c572d9374d4d298e28f3f4/src/metrics-middleware.js#L16

[kobik]

Cool @Sunny-fr , we just need to mention it in the readme

[Sunny-fr]

Ok, i'll make a proposition :)

[Sunny-fr]

@kobik here it is, sorry for the delay.
Tell me if it's ok, thanks :)

[Sunny-fr]

bump ! 👍

[kobik]

thinking of that again, IMO we need to sanitize metricsJsonRoute so it would always contain starting /

[kobik]

default is /${metricsPath}.json, right?

[kobik]

default is /${metricsPath}.json, right?

[kobik]

see my comments @Sunny-fr

[kobik]

Hi @Sunny-fr, did you have the chance to see my comments?

[Sunny-fr]

Hello There,

Yes thank you, Im running out of time these days, but I'm willing to do it asap :)

Thanks again !