StdOut.hs

{-# LANGUAGE OverloadedStrings #-}
-- | Logging to stdout is primarily intended for development purposes or creating command line status tools.
--
-- For more meaningful access to statistics, metrics should be sent to something like Librato or Graphite.
module Data.Metrics.Reporter.StdOut (
  printHealthCheck,
  printHealthChecks,
  reportMetrics,
  dumpMetrics
) where
import Control.Applicative
import Control.Concurrent.MVar
import qualified Data.HashMap.Strict as H
import Data.HealthCheck
import Data.Metrics
import qualified Data.Text as T
import qualified Data.Text.IO as T
import System.Console.ANSI

prettyPrintMetric (m, v) = T.putStr m >> T.putStr ": " >> putStrLn v

reportMetrics :: MetricRegistry IO -> IO ()
reportMetrics m = dumpMetrics m >>= mapM_ prettyPrintMetric

dumpMetrics :: MetricRegistry IO -> IO [(T.Text, String)]
dumpMetrics r = do
  ms <- readMVar $ metrics r
  let readRep (k, metricVariety) = do
        display <- case metricVariety of
          (MetricGauge g) -> show <$> value g
          (MetricCounter c) -> show <$> value c
          (MetricHistogram h) -> return ""
          (MetricMeter m) -> do
            one <- (\x -> "\t" ++ show x ++ "/minute\n") <$> oneMinuteRate m
            five <- (\x -> "\t" ++ show x ++ "/5 minutes\n") <$> fiveMinuteRate m
            fifteen <- (\x -> "\t" ++ show x ++ "/15 minutes\n") <$> fifteenMinuteRate m
            return ("\n" ++ one ++ five ++ fifteen)
          (MetricTimer t) -> (\x -> show x ++ " s") <$> mean t
        return (k, display)
  mapM readRep $ H.toList ms

fg = SetColor Foreground Vivid

-- | Pretty-print a single HealthCheck to the console using ANSI colors.
printHealthCheck :: HealthCheck -> IO ()
printHealthCheck (HealthCheck m name) = do
  s <- m
  setSGR $ case status s of
    Good -> [fg Green]
    Bad -> [fg Red]
    Ugly -> [fg Yellow]
    Unknown -> [fg Cyan]
  T.putStr "● "
  setSGR [Reset]
  T.putStr name
  maybe (T.putStr "\n") (\msg -> T.putStr ": " >> T.putStrLn msg) $ statusMessage s

-- | Pretty-print a list of HealthChecks to the console using ANSI colors.
printHealthChecks :: HealthChecks -> IO ()
printHealthChecks = mapM_ printHealthCheck