Safe Haskell	None
Language	Haskell2010

Network.Wai.Logger

Contents

High level functions
Creating a logger
Types
Date cacher
Utilities

Description

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

Synopsis

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 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.

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 = 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.