Restore the staticRoot option from older versions of Yesod's scaffolding, so I can host static files on a subdomain easily

config/settings.yml

@@ -6,9 +6,8 @@ host:           "_env:HOST:127.0.0.1"
 port:           "_env:PORT:3000" # NB: The port `yesod devel` uses is distinct from this value. Set the `yesod devel` port from the command line.
 ip-from-header: "_env:IP_FROM_HEADER:true"
 
-# Default behavior: determine the application root from the request headers.
-# Uncomment to set an explicit approot
-#approot:        "_env:APPROOT:http://localhost:3000"
+approot:        "_env:APPROOT:https://00dani.dev"
+static-root:    "_env:STATIC_ROOT:https://static.00dani.dev"
 
 # Optional values with the following production defaults.
 # In development, they default to the inverse.

src/Foundation.hs

@@ -77,6 +77,16 @@ instance Yesod App where
         120    -- timeout in minutes
         "config/client_session_key.aes"
 
+    -- Redirect static requests to a subdomain - this is recommended for best
+    -- performance, since serving static files does not need your session
+    -- cookies and they can be served from the frontend HTTP server without
+    -- hitting the app server at all.
+    -- https://github.com/yesodweb/yesod-cookbook/blob/master/cookbook/Serve-static-files-from-a-separate-domain.md
+    urlParamRenderOverride app (StaticR s) _ = do
+      staticRoot <- appStaticRoot . appSettings $ app
+      return . uncurry (joinPath app staticRoot) . renderRoute $ s
+    urlParamRenderOverride _ _ _ = Nothing
+
     -- Yesod Middleware allows you to run code before and after each handler function.
     -- The defaultYesodMiddleware adds the response header "Vary: Accept, Accept-Language" and performs authorization checks.
     -- Some users may also want to add the defaultCsrfMiddleware, which:

src/Settings.hs

@@ -43,6 +43,10 @@ data AppSettings = AppSettings
     -- ^ Get the IP address from the header when logging. Useful when sitting
     -- behind a reverse proxy.
 
+    , appStaticRoot              :: Maybe Text
+    -- ^ Base for static generated URLs. Useful for serving static assets from
+    -- a separate domain. If @Nothing@, use @appRoot@ and @appStaticDir@ instead.
+
     , appDetailedRequestLogging :: Bool
     -- ^ Use detailed request logging system
     , appShouldLogAll           :: Bool
@@ -79,6 +83,8 @@ instance FromJSON AppSettings where
         appPort                   <- o .: "port"
         appIpFromHeader           <- o .: "ip-from-header"
 
+        appStaticRoot             <- o .:? "static-root"
+
         appDetailedRequestLogging <- o .:? "detailed-logging" .!= defaultDev
         appShouldLogAll           <- o .:? "should-log-all"   .!= defaultDev
         appReloadTemplates        <- o .:? "reload-templates" .!= defaultDev