Allow multiple schemas to be exposed in one instance (#1450)

The schema to use can be selected through the headers `Accept-Profile` for GET/HEAD and `Content-Profile` for POST/PATCH/PUT/DELETE.

This is based on the https://www.w3.org/TR/dx-prof-conneg/ttps://www.w3.org/TR/dx-prof-conneg/ spec.

Also increase all memory tests by 1M(otherwise CI fails).

Co-authored-by: Mahmoud Kassem <MKassem@gk-software.com>
Co-authored-by: Mahmoud Kassem <mahmoud_k@mail.com>

main/Main.hs

@@ -45,7 +45,7 @@ import PostgREST.OpenAPI     (isMalformedProxyUri)
 import PostgREST.Types       (ConnectionStatus (..), DbStructure,
                               PgVersion (..), Schema,
                               minimumPgVersion)
-import Protolude             hiding (hPutStrLn, replace)
+import Protolude             hiding (hPutStrLn, head, replace)
 
 
 #ifndef mingw32_HOST_OS
@@ -73,11 +73,11 @@ import System.Posix.Signals
 connectionWorker
   :: ThreadId -- ^ This thread is killed if pg version is unsupported
   -> P.Pool   -- ^ The PostgreSQL connection pool
-  -> Schema   -- ^ Schema PostgREST is serving up
+  -> [Schema] -- ^ Schemas PostgREST is serving up
   -> IORef (Maybe DbStructure) -- ^ mutable reference to 'DbStructure'
   -> IORef Bool                -- ^ Used as a binary Semaphore
   -> IO ()
-connectionWorker mainTid pool schema refDbStructure refIsWorkerOn = do
+connectionWorker mainTid pool schemas refDbStructure refIsWorkerOn = do
   isWorkerOn <- readIORef refIsWorkerOn
   unless isWorkerOn $ do
     atomicWriteIORef refIsWorkerOn True
@@ -93,7 +93,7 @@ connectionWorker mainTid pool schema refDbStructure refIsWorkerOn = do
         NotConnected                -> return ()               -- Unreachable
         Connected actualPgVersion   -> do                      -- Procede with initialization
           result <- P.use pool $ do
-            dbStructure <- HT.transaction HT.ReadCommitted HT.Read $ getDbStructure schema actualPgVersion
+            dbStructure <- HT.transaction HT.ReadCommitted HT.Read $ getDbStructure schemas actualPgVersion
             liftIO $ atomicWriteIORef refDbStructure $ Just dbStructure
           case result of
             Left e -> do
@@ -162,7 +162,8 @@ main = do
   -- readOptions builds the 'AppConfig' from the config file specified on the
   -- command line
   conf <- loadDbUriFile =<< loadSecretFile =<< readOptions
-  let host = configHost conf
+  let schemas = toList $ configSchemas conf
+      host = configHost conf
       port = configPort conf
       proxy = configOpenAPIProxyUri conf
       maybeSocketAddr = configSocket conf
@@ -175,6 +176,7 @@ main = do
         . setServerName (toS $ "postgrest/" <> prettyVersion) $
         defaultSettings
 
+
   whenLeft socketFileMode panic
 
   -- Checks that the provided proxy uri is formated correctly
@@ -205,7 +207,7 @@ main = do
   connectionWorker
     mainTid
     pool
-    (configSchema conf)
+    schemas
     refDbStructure
     refIsWorkerOn
   --
@@ -227,7 +229,7 @@ main = do
     Catch $ connectionWorker
               mainTid
               pool
-              (configSchema conf)
+              schemas
               refDbStructure
               refIsWorkerOn
     ) Nothing
@@ -246,7 +248,7 @@ main = do
           (connectionWorker
              mainTid
              pool
-             (configSchema conf)
+             schemas
              refDbStructure
              refIsWorkerOn)
     in case maybeSocketAddr of