Network.Wai.Logger

Apache style logger for WAI applications.

An example:

{-# LANGUAGE OverloadedStrings #-}
module Main where

import Data.ByteString.Builder (byteString)
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 response = do
    liftIO $ aplogger req status (Just len)
    response $ responseBuilder status hdr msg
  where
    status = status200
    hdr = [("Content-Type", "text/plain")]
    pong = "PONG"
    msg = byteString pong
    len = fromIntegral $ BS.length 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.

type ServerPushLogger = Request -> ByteString -> Integer -> IO ()

HTTP/2 server push logger in Apache style.

Creating a logger

data ApacheLoggerActions

Function set of Apache style logger.

apacheLogger :: ApacheLoggerActions -> ApacheLogger

The Apache logger.

serverpushLogger :: ApacheLoggerActions -> ServerPushLogger

The HTTP/2 server push logger.

logRotator :: ApacheLoggerActions -> IO ()

This is obsoleted. Rotation is done on-demand. So, this is now an empty action.

logRemover :: ApacheLoggerActions -> IO ()

Removing resources relating to Apache logger. E.g. flushing and deallocating internal buffers.

initLogger :: IPAddrSource -> LogType -> IO FormattedTime -> 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.

LogStderr BufSize

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

LogFileNoRotate FilePath BufSize

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

LogFile FileLogSpec BufSize

Logging to a file. BufSize is a buffer size for each capability. File rotation is done on-demand.

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

Logging with a log and flush action. run flush after log each message.

data FileLogSpec :: *

The spec for logging files

Constructors

FileLogSpec

Fields

• log_file :: FilePath
• log_file_size :: Integer

  Max log file size (in bytes) before requiring rotation.

• log_backup_number :: Int

  Max number of rotated log files to keep around before overwriting the oldest one.

Utilities

showSockAddr :: SockAddr -> NumericAddress

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

logCheck :: LogType -> IO ()

Backward compability

clockDateCacher :: IO (DateCacheGetter, DateCacheUpdater)

Returning DateCacheGetter and DateCacheUpdater.

Note: Since version 2.1.2, this function uses the auto-update package internally, and therefore the DateCacheUpdater value returned need not be called. To wit, the return value is in fact an empty action.

type ZonedDate = FormattedTime

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.