Network.Wai.Logger

Apache style logger for WAI applications.

An example:

{-# LANGUAGE OverloadedStrings #-}
module Main where

import Blaze.ByteString.Builder (fromByteString)
import Control.Monad.IO.Class (liftIO)
import qualified Data.ByteString.Char8 as BS
import Network.HTTP.Types (status200)
import Network.Wai (Application, responseBuilder)
import Network.Wai.Handler.Warp (run)
import Network.Wai.Logger (withStdoutLogger, ApacheLogger)

main :: IO ()
main = withStdoutLogger $ \aplogger ->
    run 3000 $ logApp aplogger

logApp :: ApacheLogger -> Application
logApp aplogger req = do
    liftIO $ aplogger req status (Just len)
    return $ responseBuilder status hdr msg
  where
    status = status200
    hdr = [("Content-Type", "text/plain")
          ,("Content-Length", BS.pack (show len))]
    pong = "PONG"
    len = fromIntegral $ BS.length pong
    msg = toLogStr pong

High level functions

type ApacheLogger = Request -> Status -> Maybe Integer -> IO ()

Apache style logger.

withStdoutLogger :: (ApacheLogger -> IO a) -> IO a

Executing a function which takes ApacheLogger. This ApacheLogger writes log message to stdout. Each buffer (4K bytes) is flushed every second.

Creating a logger

data ApacheLoggerActions

Constructors

ApacheLoggerActions

Fields

apacheLogger :: ApacheLogger

logFlusher :: IO ()

Flushing log messages in the buffers. This is explicitly called from your program. Probably, one second and 10 seconds is proper to stdout and log files, respectively. See the source code of withStdoutLogger.

logRotator :: IO ()

Rotating log files. This is explicitly called from your program. Probably, 10 seconds is proper.

logRemover :: IO ()

Removing resources relating Apache logger.

initLogger :: IPAddrSource -> LogType -> DateCacheGetter -> IO ApacheLoggerActions

Creating ApacheLogger according to LogType.

Types

data IPAddrSource

Source from which the IP source address of the client is obtained.

Constructors

FromSocket

From the peer address of the HTTP connection.

FromHeader

From X-Real-IP: or X-Forwarded-For: in the HTTP header.

FromFallback

From the peer address if header is not found.

data LogType

Logger Type.

Constructors

LogNone

No logging.

LogStdout BufSize

Logging to stdout. BufSize is a buffer size for each capability.

LogFile FileLogSpec BufSize

Logging to a file. BufSize is a buffer size for each capability.

LogCallback (LogStr -> IO ()) (IO ())

data FileLogSpec :: *

The spec for logging files

Constructors

FileLogSpec

Fields

log_file :: FilePath

log_file_size :: Integer

log_backup_number :: Int

Date cacher

clockDateCacher :: IO (DateCacheGetter, DateCacheUpdater)

Returning DateCacheGetter and DateCacheUpdater.

type ZonedDate = ByteString

A type for zoned date.

type DateCacheGetter = IO ZonedDate

Getting cached ZonedDate.

type DateCacheUpdater = IO ()

Updateing cached ZonedDate. This should be called every second. See the source code of withStdoutLogger.

Utilities

logCheck :: LogType -> IO ()

Checking if a log file can be written if LogType is LogFile.

showSockAddr :: SockAddr -> NumericAddress

Convert SockAddr to NumericAddress. If the address is IPv4-embedded IPv6 address, the IPv4 is extracted.