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{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Com.MusicMeetsComics.Server.Config where
import Com.MusicMeetsComics.Server.Logger
import Control.Concurrent ( ThreadId )
import Control.Monad.Except ( ExceptT
, MonadError
)
import Control.Monad.IO.Class
import Control.Monad.Logger ( MonadLogger(..) )
import Control.Monad.Metrics ( Metrics
, MonadMetrics
, getMetrics
)
import qualified Control.Monad.Metrics as M
import Control.Monad.Reader ( MonadIO
, MonadReader
, ReaderT
, asks
)
import Data.Text ( pack )
import GHC.Base ( String )
import Network.Wai ( Middleware )
import Network.Wai.Handler.Warp ( Port )
import Network.Wai.Middleware.RequestLogger
( logStdout
, logStdoutDev
)
import Protolude
import Safe ( readMay )
import Servant ( ServerError )
import System.Environment ( lookupEnv )
import System.Remote.Monitoring ( forkServer
, serverMetricStore
, serverThreadId
)
-- | This type represents the effects we want to have for our application.
-- We wrap the standard Servant monad with 'ReaderT Config', which gives us
-- access to the application configuration using the 'MonadReader'
-- interface's 'ask' function.
--
-- By encapsulating the effects in our newtype, we can add layers to the
-- monad stack without having to modify code that uses the current layout.
newtype AppT m a = AppT
{ runApp :: ReaderT Config (ExceptT ServerError m) a
}
deriving (Functor, Applicative, Monad, MonadReader Config, MonadError
ServerError, MonadIO)
type App = AppT IO
-- | The Config for our application is (for now) the 'Environment' we're
-- running in and a Persistent 'ConnectionPool'.
data Config = Config
{ configEnv :: Environment
, configMetrics :: Metrics
, configEkgServer :: ThreadId
, configLogEnv :: LogEnv
, configPort :: Port
, configClient :: FilePath
}
instance Monad m => MonadMetrics (AppT m) where
getMetrics = asks configMetrics
-- | Katip instance for @AppT m@
instance MonadIO m => Katip (AppT m) where
getLogEnv = asks configLogEnv
localLogEnv = panic "not implemented"
-- | MonadLogger instance to use within @AppT m@
instance MonadIO m => MonadLogger (AppT m) where
monadLoggerLog = adapt logMsg
-- | MonadLogger instance to use in @makePool@
instance MonadIO m => MonadLogger (KatipT m) where
monadLoggerLog = adapt logMsg
-- | Right now, we're distinguishing between three environments. We could
-- also add a @Staging@ environment if we needed to.
data Environment
= Development
| Test
| Production
deriving (Eq, Show, Read)
-- | This returns a 'Middleware' based on the environment that we're in.
setLogger :: Environment -> Middleware
setLogger Test = identity
setLogger Development = logStdoutDev
setLogger Production = logStdout
-- | Web request logger (currently unimplemented and unused). For inspiration
-- see ApacheLogger from wai-logger package.
katipLogger :: LogEnv -> Middleware
katipLogger env app req respond = runKatipT env $ do
logMsg "web" InfoS "todo: received some request"
-- todo: log proper request data
liftIO $ app req respond
-- | The number of pools to use for a given environment.
envPool :: Environment -> Int
envPool Test = 1
envPool Development = 1
envPool Production = 8
-- | Allocates resources for 'Config'
acquire :: IO Config
acquire = do
port <- lookupSetting "PORT" 3001
clientDir <- lookupSetting "CLIENT_DIR"
"_bild/Com.MusicMeetsComics.Client/static"
env <- lookupSetting "ENV" Development
logEnv <- defaultLogEnv
ekgServer <- forkServer "localhost" 8000
let store = serverMetricStore ekgServer
metr <- M.initializeWith store
pure Config { configEnv = env
, configMetrics = metr
, configLogEnv = logEnv
, configPort = port
, configEkgServer = serverThreadId ekgServer
, configClient = clientDir
}
-- | Looks up a setting in the environment, with a provided default, and
-- 'read's that information into the inferred type.
lookupSetting :: Read a => String -> a -> IO a
lookupSetting env def_ = do
maybeValue <- lookupEnv env
case maybeValue of
Nothing -> return def_
Just str -> maybe (handleFailedRead str) return (readMay str)
where
handleFailedRead str = panic $ mconcat
["Failed to read [[", pack str, "]] for environment variable ", pack env]
|
