chore(health): show db time on status page and status time diffs in a human readable format

src/Database/Esqueleto/Utils.hs

@@ -55,6 +55,7 @@ module Database.Esqueleto.Utils
   , day, day', dayMaybe, interval, diffDays, diffTimes
   , exprLift
   , explicitUnsafeCoerceSqlExprValue
+  , psqlVersion_
   , truncateTable
   , module Database.Esqueleto.Utils.TH
   ) where
@@ -814,6 +815,8 @@ instance (PersistField a1, PersistField a2, PersistField b, Finite a1, Finite a2
     ]
     (E.else_ $ E.else_ $ E.veryUnsafeCoerceSqlExprValue (E.nothing :: E.SqlExpr (E.Value (Maybe ()))))
 
+psqlVersion_ :: E.SqlExpr (E.Value Text)
+psqlVersion_ = E.unsafeSqlFunction "VERSION" ()
 
 -- Suspected to cause trouble. Needs more testing!
 -- truncateTable :: (MonadIO m, BackendCompatible SqlBackend backend, PersistEntity record)

src/Handler/Admin/Test.hs

@@ -28,7 +28,9 @@ import Text.Hamlet
 -- import Handler.Utils.I18n
 
 import Handler.Admin.Test.Download (testDownload)
-
+import qualified Database.Esqueleto.Experimental as E (selectOne, unValue)
+import qualified Database.Esqueleto.PostgreSQL as E  (now_)
+import qualified Database.Esqueleto.Utils as E (psqlVersion_)
 
 -- BEGIN - Buttons needed only here
 data ButtonCreate = CreateMath | CreateInf | CrashApp -- Dummy for Example
@@ -226,6 +228,9 @@ postAdminTestR = do
 
   UniWorX{ appSettings' = AppSettings{..} } <- getYesod
 
+  psqlVersion <- runDBRead $ E.selectOne $ return E.psqlVersion_
+  dbTime      <- runDBRead $ E.selectOne $ return E.now_
+
   let locallyDefinedPageHeading = [whamlet|Admin TestPage for Uni2work|]
   siteLayout locallyDefinedPageHeading $ do
   -- defaultLayout $ do
@@ -327,6 +332,17 @@ postAdminTestR = do
           <dd .deflist__dd>#{tshow appSynchroniseAvsUsersWithin}
     |]
 
+    [whamlet|
+      <section>
+        <h2> PostgreSQL Information
+        <dl .deflist>
+          $maybe pver <- psqlVersion
+            <dt .deflist__dt>DB Version
+            <dd .deflist__dd>#{E.unValue pver}
+          $maybe ptme <- dbTime
+            <dt .deflist__dt>DB Time
+            <dd .deflist__dd>#{tshow (E.unValue ptme)}
+    |]
 
 
 

src/Handler/Health.hs

@@ -20,6 +20,9 @@ import Control.Concurrent.STM.Delay
 
 import System.Environment (lookupEnv) -- while git version number is not working
 
+import qualified Database.Esqueleto.Experimental as E
+import qualified Database.Esqueleto.PostgreSQL as E  (now_)
+
 -- import Data.FileEmbed (embedStringFile)
 
 getHealthR :: Handler TypedContent
@@ -114,10 +117,16 @@ getInstanceR = do
 getStatusR :: Handler Html
 getStatusR = do
   starttime <- getsYesod appStartTime
-  (currtime, env_version) <- liftIO $ (,) <$> getCurrentTime <*> lookupEnv "VERSION_NR"
+  dbTime <- runDBRead $ E.selectOne $ return E.now_
+  (currtime,env_version) <- liftIO $ (,) <$> getCurrentTime <*> lookupEnv "VERSION_NR"
   -- ft <- formatTime'  "%Y-%m-%d %H:%M:%S" currtime
   let diffTime :: UTCTime -> Text
-      diffTime = pack . iso8601Show . calendarTimeTime . fromIntegral . truncate . diffUTCTime currtime
+      diffTime t =
+        let tdiff = diffUTCTime currtime t
+        in if 64 > abs tdiff
+            then tshow tdiff
+            else pack . iso8601Show . calendarTimeTime . fromIntegral $ truncate tdiff
+
   withUrlRenderer
     [hamlet|
       $doctype 5
@@ -129,8 +138,13 @@ getStatusR = do
             <p>
               Environment version #{env_ver}
           <p>
-            Current Time <br>
+            Current Application Time <br>
             #{show currtime} <br>
+          $maybe dbtval <- dbTime
+            $with dbt <- E.unValue dbtval
+              Current Database Time <br>
+              #{show dbt} #
+              Difference: #{diffTime dbt} <br>
           <p>
             Instance Start <br>
             #{show starttime} #