add a Settings.yaml file for dynamic settings

also command line to check for environment argument

scaffold/Controller_hs.cg

@@ -35,14 +35,22 @@ getRobotsR = return $ RepPlain $ toContent ("User-agent: *" :: ByteString)
 -- performs initialization and creates a WAI application. This is also the
 -- place to put your migrate statements to have automatic database
 -- migrations handled by Yesod.
-with~sitearg~ :: (Application -> IO a) -> IO a
-with~sitearg~ f = Settings.withConnectionPool $ \p -> do
+with~sitearg~ :: AppConfig -> (Application -> IO a) -> IO a
+with~sitearg~ conf f = do
+  Settings.withConnectionPool conf $ \p -> do
     runConnectionPool (runMigration migrateAll) p
-    let h = ~sitearg~ s p
+    let h = ~sitearg~ conf s p
     toWaiApp h >>= f
   where
-    s = static Settings.staticdir
+    s = static Settings.staticDir
+
+with~sitearg~LoadConfig :: Settings.AppEnvironment -> (Application -> IO a) -> IO a
+with~sitearg~LoadConfig env f = do
+  conf <- Settings.loadConfig Settings.Development
+  withFoobar conf f
+
 
 withDevelApp :: Dynamic
-withDevelApp = toDyn (with~sitearg~ :: (Application -> IO ()) -> IO ())
+withDevelApp = do
+  toDyn ((with~sitearg~LoadConfig Settings.Development):: (Application -> IO ()) -> IO ())
 

scaffold/Settings_hs.cg

@@ -16,9 +16,11 @@ module Settings
     , ConnectionPool
     , withConnectionPool
     , runConnectionPool
-    , approot
-    , staticroot
-    , staticdir
+    , staticRoot
+    , staticDir
+    , loadConfig
+    , AppEnvironment(..)
+    , AppConfig(..)
     ) where
 
 import qualified Text.Hamlet as H
@@ -31,26 +33,67 @@ import Yesod (MonadControlIO, addWidget, addCassius, addJulius, addLucius)
 import Data.Monoid (mempty, mappend)
 import System.Directory (doesFileExist)
 import Data.Text (Text)
+import Data.Object
+import Data.Object.Yaml
+import Control.Monad (join)
 
--- | The base URL for your application. This will usually be different for
--- development and production. Yesod automatically constructs URLs for you,
--- so this value must be accurate to create valid links.
--- Please note that there is no trailing slash.
-approot :: Text
-approot =
-#ifdef PRODUCTION
--- You probably want to change this. If your domain name was "yesod.com",
--- you would probably want it to be:
--- > "http://yesod.com"
-  "http://localhost:3000"
-#else
-  "http://localhost:3000"
-#endif
+data AppEnvironment = Test
+                    | Development
+                    | Staging
+                    | Production
+                    deriving (Eq, Show, Read, Enum, Bounded)
+
+-- | dynamic per-environment configuration loaded from a YAML file
+--   use this to avoid the need to re-compile between staging and production environments
+data AppConfig = AppConfig {
+    appEnv :: AppEnvironment
+
+  , appPort :: Int
+
+    -- | Your application will keep a connection pool and take connections from
+    -- there as necessary instead of continually creating new connections. This
+    -- value gives the maximum number of connections to be open at a given time.
+    -- If your application requests a connection when all connections are in
+    -- use, that request will fail. Try to choose a number that will work well
+    -- with the system resources available to you while providing enough
+    -- connections for your expected load.
+    --
+    -- Connections are returned to the pool as quickly as possible by
+    -- Yesod to avoid resource exhaustion. A connection is only considered in
+    -- use while within a call to runDB.
+  , connectionPoolSize :: Int
+
+    -- | The base URL for your application. This will usually be different for
+    -- development and production. Yesod automatically constructs URLs for you,
+    -- so this value must be accurate to create valid links.
+    -- Please note that there is no trailing slash.
+    --
+    -- You probably want to change this! If your domain name was "yesod.com",
+    -- you would probably want it to be:
+    -- > "http://yesod.com"
+  , appRoot :: Text
+}
+
+loadConfig :: AppEnvironment -> IO AppConfig
+loadConfig env = do
+    allSettings <- (join $ decodeFile ("Settings.yaml" :: String)) >>= fromMapping
+    settings <- lookupMapping (show env) allSettings
+    appPortS <- lookupScalar "appPort" settings
+    appRootS <- lookupScalar "appRoot" settings
+    connectionPoolSizeS <- lookupScalar "connectionPoolSize" settings
+    return $ AppConfig {
+      appEnv = env
+    , appPort = read $ appPortS
+    , appRoot = read $ appRootS
+    , connectionPoolSize = read $ connectionPoolSizeS
+    }
+
+-- Static setting below. Changing these requires a recompile
 
 -- | The location of static files on your system. This is a file system
 -- path. The default value works properly with your scaffolded site.
-staticdir :: FilePath
-staticdir = "static"
+staticDir :: FilePath
+staticDir = "static"
 
 -- | The base URL for your static files. As you can see by the default
 -- value, this can simply be "static" appended to your application root.
@@ -65,8 +108,9 @@ staticdir = "static"
 -- have to make a corresponding change here.
 --
 -- To see how this value is used, see urlRenderOverride in ~sitearg~.hs
-staticroot :: Text
-staticroot = approot `mappend` "/static"
+staticRoot :: AppConfig ->  Text
+staticRoot conf = (appRoot conf) `mappend` "/static"
+
 
 -- | The database connection string. The meaning of this string is backend-
 -- specific.
@@ -78,20 +122,6 @@ connStr =
   "~connstr1~"
 #endif
 
--- | Your application will keep a connection pool and take connections from
--- there as necessary instead of continually creating new connections. This
--- value gives the maximum number of connections to be open at a given time.
--- If your application requests a connection when all connections are in
--- use, that request will fail. Try to choose a number that will work well
--- with the system resources available to you while providing enough
--- connections for your expected load.
---
--- Also, connections are returned to the pool as quickly as possible by
--- Yesod to avoid resource exhaustion. A connection is only considered in
--- use while within a call to runDB.
-connectionCount :: Int
-connectionCount = 10
-
 -- The rest of this file contains settings which rarely need changing by a
 -- user.
 
@@ -155,8 +185,8 @@ widgetFile x = do
 -- database actions using a pool, respectively. It is used internally
 -- by the scaffolded application, and therefore you will rarely need to use
 -- them yourself.
-withConnectionPool :: MonadControlIO m => (ConnectionPool -> m a) -> m a
-withConnectionPool = with~upper~Pool connStr connectionCount
+withConnectionPool :: MonadControlIO m => AppConfig -> (ConnectionPool -> m a) -> m a
+withConnectionPool conf = with~upper~Pool connStr (connectionPoolSize conf)
 
 runConnectionPool :: MonadControlIO m => SqlPersist m a -> ConnectionPool -> m a
 runConnectionPool = runSqlPool

scaffold/Settings_yaml.cg

@@ -0,0 +1,16 @@
+Default: &default
+  appRoot: http://localhost
+  appPort: 3000
+  connectionPoolLimit: 10
+
+Development:
+  <<: *defaults
+
+Test:
+  <<: *defaults
+
+Staging:
+  <<: *defaults
+
+Production:
+  <<: *defaults

scaffold/cabal.cg

@@ -62,6 +62,8 @@ executable         ~project~
                  , hamlet
                  , hjsmin
                  , transformers
+                 , data-object
+                 , data-object-yaml
                  , warp
                  , blaze-builder
-
+                 , cmdargs

scaffold/mini-Controller_hs.cg

@@ -34,13 +34,13 @@ getRobotsR = return $ RepPlain $ toContent ("User-agent: *" :: ByteString)
 -- performs initialization and creates a WAI application. This is also the
 -- place to put your migrate statements to have automatic database
 -- migrations handled by Yesod.
-with~sitearg~ :: (Application -> IO a) -> IO a
-with~sitearg~ f = do
-    let h = ~sitearg~ s
+with~sitearg~ :: AppEnvironment -> (Application -> IO a) -> IO a
+with~sitearg~ appEnv f = do
+    let h = ~sitearg~ appEnv s
     toWaiApp h >>= f
   where
     s = static Settings.staticdir
 
 withDevelApp :: Dynamic
-withDevelApp = toDyn (with~sitearg~ :: (Application -> IO ()) -> IO ())
+withDevelApp = toDyn (with~sitearg~ Development :: (Application -> IO ()) -> IO ())
 

scaffold/mini-cabal.cg

@@ -55,6 +55,8 @@ executable         ~project~
                  , template-haskell
                  , hamlet
                  , transformers
+                 , data-object
+                 , data-object-yaml
                  , wai
                  , warp
                  , blaze-builder

scaffold/mini-sitearg_hs.cg

@@ -30,7 +30,8 @@ import qualified Data.Text as T
 -- starts running, such as database connections. Every handler will have
 -- access to the data present here.
 data ~sitearg~ = ~sitearg~
-    { getStatic :: Static -- ^ Settings for static file serving.
+    { appEnv :: Settings.AppEnvironment
+    , getStatic :: Static -- ^ Settings for static file serving.
     }
 
 -- | A useful synonym; most of the handler functions in your application

scaffold/sitearg_hs.cg

@@ -40,7 +40,8 @@ import qualified Data.Text as T
 -- starts running, such as database connections. Every handler will have
 -- access to the data present here.
 data ~sitearg~ = ~sitearg~
-    { getStatic :: Static -- ^ Settings for static file serving.
+    { settings :: Settings.AppConfig
+    , getStatic :: Static -- ^ Settings for static file serving.
     , connPool :: Settings.ConnectionPool -- ^ Database connection pool.
     }
 
@@ -76,7 +77,7 @@ mkYesodData "~sitearg~" $(parseRoutesFile "config/routes")
 -- Please see the documentation for the Yesod typeclass. There are a number
 -- of settings which can be configured by overriding methods here.
 instance Yesod ~sitearg~ where
-    approot _ = Settings.approot
+    approot = Settings.appRoot . settings
 
     defaultLayout widget = do
         mmsg <- getMessage
@@ -86,9 +87,9 @@ instance Yesod ~sitearg~ where
         hamletToRepHtml $(Settings.hamletFile "default-layout")
 
     -- This is done to provide an optimization for serving static files from
-    -- a separate domain. Please see the staticroot setting in Settings.hs
-    urlRenderOverride a (StaticR s) =
-        Just $ uncurry (joinPath a Settings.staticroot) $ renderRoute s
+    -- a separate domain. Please see the staticRoot setting in Settings.hs
+    urlRenderOverride y (StaticR s) =
+        Just $ uncurry (joinPath y (Settings.staticRoot $ settings y)) $ renderRoute s
     urlRenderOverride _ _ = Nothing
 
     -- The page to be redirected to when authentication is required.
@@ -106,7 +107,7 @@ instance Yesod ~sitearg~ where
                             Left _ -> content
                             Right y -> y
                     else content
-        let statictmp = Settings.staticdir ++ "/tmp/"
+        let statictmp = Settings.staticDir ++ "/tmp/"
         liftIO $ createDirectoryIfMissing True statictmp
         let fn' = statictmp ++ fn
         exists <- liftIO $ doesFileExist fn'

scaffold/test_hs.cg

@@ -1,20 +1,51 @@
-{-# LANGUAGE CPP #-}
-#if PRODUCTION
+{-# LANGUAGE CPP, DeriveDataTypeable #-}
+import qualified Settings as Settings
 import Controller (with~sitearg~)
 import Network.Wai.Handler.Warp (run)
+import System.Console.CmdArgs
+import Data.Char (toUpper, toLower)
 
+#if PRODUCTION
 main :: IO ()
-main = with~sitearg~ $ run 3000
+main = do
+    appEnv <- getAppEnv
+    config <- Settings.loadConfig appEnv
+    with~sitearg~ config $ run (Settings.appPort settings)
+
 #else
-import Controller (with~sitearg~)
 import System.IO (hPutStrLn, stderr)
 import Network.Wai.Middleware.Debug (debug)
-import Network.Wai.Handler.Warp (run)
 
 main :: IO ()
 main = do
-    let port = 3000
-    hPutStrLn stderr $ "Application launched, listening on port " ++ show port
-    with~sitearg~ $ run port . debug
+    appEnv <- getAppEnv
+    config <- Settings.loadConfig appEnv
+    hPutStrLn stderr $ "Application launched, listening on port " ++ show (Settings.appPort config)
+    with~sitearg~ config $ run (Settings.appPort config) . debug
 #endif
 
+data ArgConfig = ArgConfig {environment :: String}
+                 deriving (Show, Data, Typeable)
+
+config = ArgConfig{ environment = def
+  &= help "application environment, one of:" ++ (foldl1 (++) environments)
+  &= typ "ENVIRONMENT"
+#if PRODUCTION
+  &= opt "production"
+#else
+  &= opt "development"
+#endif
+}
+
+environments :: [String]
+environments = map show ([minBound..maxBound] :: [Settings.AppEnvironment])
+
+
+-- | retrieve the -e environment option
+getAppEnv :: IO Settings.AppEnvironment
+getAppEnv = do
+    cfg <- cmdArgs config
+    return $ read $ capitalize $ environment cfg
+  where
+    capitalize [] = []
+    capitalize (x:xs) = toUpper x : map toLower xs

tests/runscaffold.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+cd .. &&
+cabal clean && cabal install &&
+rm -rf foobar && runghc scaffold.hs init < sample-input.txt && cd foobar && cabal install && cabal install -fdevel && cd .. &&
+cd tests

tests/sample-input.txt

@@ -0,0 +1,4 @@
+Michael
+foobar
+Foobar
+s