Prometheus

MetricsOps algebra capable of recording Prometheus metrics

For example, the following code would wrap a org.http4s.HttpRoutes with a org.http4s.server.middleware.Metrics that records metrics to a given metric registry.

import cats.effect.{Resource, IO}
import org.http4s.server.middleware.Metrics
import org.http4s.metrics.Prometheus

val meteredRoutes: Resource[IO, HttpRoutes[IO]] =
 Prometheus.metricsOps[IO](registry, "server").map(ops => Metrics[IO](ops)(testRoutes))

Analogously, the following code would wrap a org.http4s.client.Client with a org.http4s.client.middleware.Metrics that records metrics to a given metric registry, classifying the metrics by HTTP method.

import cats.effect.{Resource, IO}
import org.http4s.client.middleware.Metrics
import org.http4s.metrics.Prometheus

val classifierFunc = (r: Request[IO]) => Some(r.method.toString.toLowerCase)
val meteredClient: Resource[IO, Client[IO]] =
 Prometheus.metricsOps[IO](registry, "client").map(ops => Metrics[IO](ops, classifierFunc)(client))

Registers the following metrics:

{prefix}_response_duration_seconds{labels=classifier,method,phase} - Histogram

{prefix}_active_request_count{labels=classifier} - Gauge

{prefix}_request_count{labels=classifier,method,status} - Counter

{prefix}_abnormal_terminations{labels=classifier,termination_type} - Histogram

Labels --

method: Enumeration values: get, put, post, head, move, options, trace, connect, delete, other

phase: Enumeration values: headers, body

code: Enumeration values: 1xx, 2xx, 3xx, 4xx, 5xx

termination_type: Enumeration values: abnormal, error, timeout