refactor: make observation messages pure (#3250)

removes the observation messages from the Logger

src/PostgREST/Observation.hs

@@ -1,29 +1,37 @@
+{-# LANGUAGE LambdaCase #-}
 {-|
 Module      : PostgREST.Observation
 Description : Module for observability types
 -}
 module PostgREST.Observation
   ( Observation(..)
+  , observationMessage
   ) where
 
+import qualified Data.ByteString.Lazy  as LBS
+import qualified Data.Text.Encoding    as T
 import qualified Hasql.Pool            as SQL
 import qualified Network.Socket        as NS
-import           PostgREST.SchemaCache (SchemaCache)
+import           Numeric               (showFFloat)
+import qualified PostgREST.Error       as Error
+import           PostgREST.SchemaCache (SchemaCache, showSummary)
 
 import Protolude
+import Protolude.Partial (fromJust)
 
 data Observation
   = AdminStartObs (Maybe Int)
-  | AppStartObs ByteString
+  | AppServerStartObs ByteString
   | AppServerPortObs NS.PortNumber
   | AppServerUnixObs FilePath
-  | AppDBConnectAttemptObs
-  | AppExitFatalObs Text
-  | AppExitDBNoRecoveryObs
-  | AppDBConnectedObs Text
-  | AppSCacheFatalErrorObs SQL.UsageError Text
-  | AppSCacheNormalErrorObs SQL.UsageError
-  | AppSCacheLoadSuccessObs SchemaCache Double
+  | DBConnectAttemptObs
+  | ExitFatalObs Text
+  | ExitDBNoRecoveryObs
+  | DBConnectedObs Text
+  | SchemaCacheFatalErrorObs SQL.UsageError Text
+  | SchemaCacheNormalErrorObs SQL.UsageError
+  | SchemaCacheQueriedObs Double
+  | SchemaCacheLoadedObs SchemaCache
   | ConnectionRetryObs Int
   | ConnectionPgVersionErrorObs SQL.UsageError
   | DBListenerStart Text
@@ -37,3 +45,61 @@ data Observation
   | QueryRoleSettingsErrorObs SQL.UsageError
   | QueryErrorCodeHighObs SQL.UsageError
   | PoolAcqTimeoutObs SQL.UsageError
+
+observationMessage :: Observation -> Text
+observationMessage = \case
+  AdminStartObs port ->
+    "Admin server listening on port " <> show (fromIntegral (fromJust port) :: Integer)
+  AppServerStartObs ver ->
+    "Starting PostgREST " <> T.decodeUtf8 ver <> "..."
+  AppServerPortObs port ->
+    "Listening on port " <> show port
+  AppServerUnixObs sock ->
+    "Listening on unix socket " <> show sock
+  DBConnectAttemptObs ->
+    "Attempting to connect to the database..."
+  ExitFatalObs reason ->
+    "Fatal error encountered. " <> reason
+  ExitDBNoRecoveryObs ->
+    "Automatic recovery disabled, exiting."
+  DBConnectedObs ver ->
+    "Successfully connected to " <> ver
+  SchemaCacheFatalErrorObs usageErr hint ->
+    "A fatal error ocurred when loading the schema cache. " <> hint <> ". " <> jsonMessage usageErr
+  SchemaCacheNormalErrorObs usageErr ->
+    "An error ocurred when loading the schema cache. " <> jsonMessage usageErr
+  SchemaCacheQueriedObs resultTime ->
+    "Schema cache queried in " <> showMillis resultTime  <> " milliseconds"
+  SchemaCacheLoadedObs sCache ->
+    "Schema cache loaded " <> showSummary sCache
+  ConnectionRetryObs delay ->
+    "Attempting to reconnect to the database in " <> (show delay::Text) <> " seconds..."
+  ConnectionPgVersionErrorObs usageErr ->
+    jsonMessage usageErr
+  DBListenerStart channel -> do
+    "Listening for notifications on the " <> channel <> " channel"
+  DBListenerFailNoRecoverObs ->
+    "Automatic recovery disabled, exiting."
+  DBListenerFailRecoverObs channel ->
+    "Retrying listening for notifications on the " <> channel <> " channel.."
+  ConfigReadErrorObs ->
+    "An error ocurred when trying to query database settings for the config parameters"
+  ConfigReadErrorFatalObs usageErr hint ->
+    hint <> ". " <> jsonMessage usageErr
+  ConfigReadErrorNotFatalObs usageErr ->
+    jsonMessage usageErr
+  QueryRoleSettingsErrorObs usageErr ->
+    "An error ocurred when trying to query the role settings. " <> jsonMessage usageErr
+  QueryErrorCodeHighObs usageErr ->
+    jsonMessage usageErr
+  ConfigInvalidObs err ->
+    "Failed reloading config: " <> err
+  ConfigSucceededObs ->
+     "Config reloaded"
+  PoolAcqTimeoutObs usageErr ->
+    jsonMessage usageErr
+  where
+    showMillis :: Double -> Text
+    showMillis x = toS $ showFFloat (Just 1) (x * 1000) ""
+
+    jsonMessage err = T.decodeUtf8 . LBS.toStrict . Error.errorPayload $ Error.PgError False err