[#2450] Initialize Sentry service at application start

Updated the application to initialize the Sentry service at the
beginning of the app lifecycle rather than during each exception
occurrence. This change ensures that the Sentry service is set up once
when the application starts, saving resources and potentially increasing
the application's performance by avoiding repetitive initializations.
The Sentry service is passed to the exception handler during setup and
is used consistently throughout the application's uptime. This aligns
with the user story's requirement to optimize exception handling
efficiency by centralizing Sentry service initialization.

govtool/backend/app/Main.hs

@@ -53,7 +53,7 @@ import           System.Clock                           (TimeSpec (TimeSpec))
 import           System.IO                              (stderr)
 import           System.Log.Raven                       (initRaven, register, silentFallback)
 import           System.Log.Raven.Transport.HttpConduit (sendRecord)
-import           System.Log.Raven.Types                 (SentryLevel (Error), SentryRecord (..))
+import           System.Log.Raven.Types                 (SentryLevel (Error), SentryRecord (..), SentryService)
 import           System.TimeManager                     (TimeoutThread (..))
 
 import           VVA.API
@@ -71,12 +71,18 @@ main :: IO ()
 main = do
   commandLineConfig <- execParser cmdParser
   vvaConfig <- loadVVAConfig (clcConfigPath commandLineConfig)
+  sentryService <-
+    initRaven
+      (sentryDSN vvaConfig)
+      id
+      sendRecord
+      silentFallback
   case clcCommand commandLineConfig of
-    StartApp   -> startApp vvaConfig
+    StartApp   -> startApp vvaConfig sentryService
     ShowConfig -> Text.putStrLn $ vvaConfigToText vvaConfig
 
-startApp :: VVAConfig -> IO ()
-startApp vvaConfig = do
+startApp :: VVAConfig -> SentryService -> IO ()
+startApp vvaConfig sentryService = do
   let vvaPort = serverPort vvaConfig
       vvaHost = fromString (Text.unpack (serverHost vvaConfig))
       settings =
@@ -92,7 +98,7 @@ startApp vvaConfig = do
                       ++ show vvaPort
                   )
             )
-          $ setOnException (exceptionHandler vvaConfig) defaultSettings
+          $ setOnException (exceptionHandler vvaConfig sentryService) defaultSettings
   cacheEnv <- do
     let newCache = Cache.newCache (Just $ TimeSpec (fromIntegral (cacheDurationSeconds vvaConfig)) 0)
     proposalListCache <- newCache
@@ -122,8 +128,8 @@ startApp vvaConfig = do
   server' <- mkVVAServer appEnv
   runSettings settings server'
 
-exceptionHandler :: VVAConfig -> Maybe Request -> SomeException -> IO ()
-exceptionHandler vvaConfig mRequest exception = do
+exceptionHandler :: VVAConfig -> SentryService -> Maybe Request -> SomeException -> IO ()
+exceptionHandler vvaConfig sentryService mRequest exception = do
   print mRequest
   print exception
   let isNotTimeoutThread x = case fromException x of
@@ -135,12 +141,6 @@ exceptionHandler vvaConfig mRequest exception = do
   guard . isNotTimeoutThread $ exception
   guard . isNotConnectionClosedByPeer $ exception
   let env = sentryEnv vvaConfig
-  sentryService <-
-    initRaven
-      (sentryDSN vvaConfig)
-      id
-      sendRecord
-      silentFallback
   register
     sentryService
     "vva.be"