http4s-prometheus exporter

Provides instumentation to wrap http4s HttpService[F] with a prometheus metric collecting middleware.

Add to sbt

   "io.github.yannick-cw" %% "http4s-prometheus"   % x.x.x

Usage

Wrap services you want to monitor and provide a metrics service endpoint for prometheus:

  import io.github.yannick_cw.http4s_prometheus.{MetricsMiddleware, MetricsService}
  private val M = MetricsMiddleware()
  val httpService  = HttpService[IO] { case GET -> Root / "hi" => Ok() }
  val httpService2 = HttpService[IO] { case GET -> Root / "Ups" => NotFound() }
  val routing = Router(
    "one"         -> M.collect("service 1 name", httpService),
    "two"         -> M.collect("service 2 name", httpService2),
    "/metrics" -> MetricsService[IO]()
  )

Via /metrics prometheus can now access the http request counter

# HELP http_requests_total Total http requests received
# TYPE http_requests_total counter
http_requests_total{service="service 1 name",status="200",} 10.0

and a request duration histogram in seconds

# HELP http_requests_duration_seconds Histogram of the response time of http requests in Seconds
# TYPE http_requests_duration_seconds histogram
http_requests_duration_seconds_bucket{service="service 2 name",status="404",le="0.01",} 9.0

Additional settings

If you want you can supply the buckets for the Histogram and a custom CollectorRegistry

MetricsMiddleware(List(0.01, 0.025), CollectorRegistry.defaultRegistry)