Prometheus backend

To use, add the following dependency to your project:

"com.softwaremill.sttp.client3" %% "prometheus-backend" % "3.10.2"

and some imports:

import sttp.client3.prometheus._

This backend depends on Prometheus JVM Client. Keep in mind this backend registers histograms and gathers request times, but you have to expose those metrics to Prometheus e.g. using prometheus-akka-http.

The Prometheus backend wraps any other backend, for example:

import sttp.client3.akkahttp._
val backend = PrometheusBackend(AkkaHttpBackend())

It gathers request execution times in Histogram. It uses by default sttp_request_latency name, defined in PrometheusBackend.DefaultHistogramName. It is possible to define custom histograms name by passing function mapping request to histogram name:

import sttp.client3.akkahttp._
val backend = PrometheusBackend(
  AkkaHttpBackend(), 
  requestToHistogramNameMapper = request => Some(HistogramCollectorConfig(request.uri.host.getOrElse("example.com")))
)

You can disable request histograms by passing None returning function:

import sttp.client3.akkahttp._
val backend = PrometheusBackend(AkkaHttpBackend(), requestToHistogramNameMapper = _ => None)

This backend also offers Gauge with currently in-progress requests number. It uses by default sttp_requests_in_progress name, defined in PrometheusBackend.DefaultRequestsInProgressGaugeName. It is possible to define custom gauge name by passing function mapping request to gauge name:

import sttp.client3.akkahttp._
val backend = PrometheusBackend(
  AkkaHttpBackend(), 
  requestToInProgressGaugeNameMapper = request => Some(CollectorConfig(request.uri.host.getOrElse("example.com")))
)

You can disable request in-progress gauges by passing None returning function:

import sttp.client3.akkahttp._
val backend = PrometheusBackend(AkkaHttpBackend(), requestToInProgressGaugeNameMapper = _ => None)