Prometheus Haskell Client

Latest on Hackage:0.4.1

This package is not currently in any snapshots. If you're interested in using it, we recommend adding it to Stackage Nightly. Doing so will make builds more reliable, and allow to host generated Haddocks.

BSD3 licensed by Luke Hoersten

Prometheus Haskell Client

A simple and modern, type safe, idiomatic Haskell client for Prometheus monitoring. Specifically there is no use of unsafe IO or manual ByteString construction from lists of bytes. Batteries-included web server. . [Usage Example]

Usage Example

{-# LANGUAGE OverloadedStrings #-}

module Example where

import           Control.Monad.IO.Class                         (liftIO)
import           System.Metrics.Prometheus.Concurrent.Http      (serveHttpTextMetricsT)
import           System.Metrics.Prometheus.Concurrent.RegistryT
import           System.Metrics.Prometheus.Metric.Counter       (inc)
import           System.Metrics.Prometheus.MetricId

main :: IO ()
main = runRegistryT $ do
    -- Labels can be defined as lists or added to an empty label set
    connectSuccessGauge <- registerGauge "example_connections" (fromList [("login", "success")])
    connectFailureGauge <- registerGauge "example_connections" (addLabel "login" "failure" mempty)
    connectCounter <- registerCounter "example_connection_total" mempty
    latencyHistogram <- registerHistogram "example_round_trip_latency_ms" mempty [10, 20..100]

    liftIO $ inc connectCounter -- increment a counter

    -- [...] pass metric handles to the rest of the app

    serveHttpTextMetricsT 8080 ["metrics"] -- http://localhost:8080/metric server

Advanced Usage

A Registry and StateT-based RegistryT are available for unit testing or generating lists of [IO a] actions that can be sequenced and returned from pure code to be applied.


  • [ ] Implement help docstrings.
  • [ ] Implement GHC-specific metrics.
  • [ ] Implement summary metric.
  • [ ] Encode name and labels on register.
  • [x] Implement ReaderT for Concurrent Registry.
  • [x] Library documentation and example.
  • [ ] Name and label validation
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