Push.hs

module System.Metrics.Prometheus.Http.Push
       ( pushHttpProtoMetrics
       )
       where

import           Control.Concurrent                               (threadDelay)
import           Control.Monad                                    (forever)
import           Data.Map                                         (foldMapWithKey)
import           Data.Text                                        (Text, unpack)
import           Network.Wreq.Session                             (put,
                                                                   withSession)
import           System.Metrics.Prometheus.Encode.ProtocolBuffers ()
import           System.Metrics.Prometheus.MetricId               (Labels (..))
import           System.Metrics.Prometheus.Registry               (RegistrySample)

-- | Push metrics to a pushgateway.
pushHttpProtoMetrics :: String            -- ^ The base URL of the pushgateway, including the port number.
                     -> Text              -- ^ The name of this job.
                     -> Labels            -- ^ The label set to use as a grouping key for these metrics.
                     -> Int               -- ^ Push frequency, in microseconds.
                     -> IO RegistrySample -- ^ The action to get the latest metrics.
                     -> IO ()
pushHttpProtoMetrics base job (Labels ls) frequency get =
    withSession $ \session -> forever $
      get >>= put session url >> threadDelay frequency
  where
    url = base ++ "/metrics/job/" ++ unpack job ++
        foldMapWithKey (\k v -> "/" ++ unpack k ++ "/" ++ unpack v) ls