refactor: move socket creation and management to App module

Right now listening sockets initialization, management and usage is split between App, AppState and Admin modules: they are created in AppState.init and remembered in AppState but used only in App and Admin.

It has several negative consequences:
- sockets are initialized even if not needed (eg. command line invocations like dump-config or dump-schema)
- it is impossible to start listening on a socket after initial schema cache load because it requires AppState

This change decouples listen socket management from AppState. Sockets are created only when needed (ie. not in command line tools invocation) and passed to admin application and to Warp by the App module.

src/PostgREST/AppState.hs

@@ -13,10 +13,7 @@ module PostgREST.AppState
   , getNextListenerDelay
   , getTime
   , getJwtCacheState
-  , getSocketREST
-  , getSocketAdmin
   , init
-  , initSockets
   , initWithPool
   , putNextListenerDelay
   , putSchemaCache
@@ -32,13 +29,11 @@ module PostgREST.AppState
 
 import qualified Data.ByteString.Char8      as BS
 import           Data.Either.Combinators    (whenLeft)
-import qualified Data.Text                  as T (unpack)
 import qualified Hasql.Pool                 as SQL
 import qualified Hasql.Pool.Config          as SQL
 import qualified Hasql.Session              as SQL
 import qualified Hasql.Transaction.Sessions as SQL
 import qualified Network.HTTP.Types.Status  as HTTP
-import qualified Network.Socket             as NS
 import qualified PostgREST.Auth.JwtCache    as JwtCache
 import qualified PostgREST.Error            as Error
 import qualified PostgREST.Logger           as Logger
@@ -70,10 +65,7 @@ import PostgREST.SchemaCache             (SchemaCache (..),
                                           querySchemaCache,
                                           showSummary)
 import PostgREST.SchemaCache.Identifiers (quoteQi)
-import PostgREST.Unix                    (createAndBindDomainSocket)
 
-import Data.Streaming.Network (bindPortTCP, bindRandomPortTCP)
-import Data.String            (IsString (..))
 import Protolude
 
 data AppState = AppState
@@ -99,10 +91,6 @@ data AppState = AppState
   , stateNextDelay         :: IORef Int
   -- | Keeps track of the next delay for the listener
   , stateNextListenerDelay :: IORef Int
-  -- | Network socket for REST API
-  , stateSocketREST        :: NS.Socket
-  -- | Network socket for the admin UI
-  , stateSocketAdmin       :: Maybe NS.Socket
   -- | Observation handler
   , stateObserver          :: ObservationHandler
   -- | JWT Cache
@@ -117,8 +105,6 @@ newtype SchemaCacheStatus = SchemaCacheStatus
   { getSCStatusMVar :: MVar ()
   }
 
-type AppSockets = (NS.Socket, Maybe NS.Socket)
-
 init :: AppConfig -> IO AppState
 init conf@AppConfig{configLogLevel, configDbPoolSize} = do
   loggerState  <- Logger.init
@@ -128,12 +114,10 @@ init conf@AppConfig{configLogLevel, configDbPoolSize} = do
   observer $ AppStartObs prettyVersion
 
   pool <- initPool conf observer
-  (sock, adminSock) <- initSockets conf
-  state' <- initWithPool (sock, adminSock) pool conf loggerState metricsState observer
-  pure state' { stateSocketREST = sock, stateSocketAdmin = adminSock}
+  initWithPool pool conf loggerState metricsState observer --{ stateSocketREST = sock, stateSocketAdmin = adminSock}
 
-initWithPool :: AppSockets -> SQL.Pool -> AppConfig -> Logger.LoggerState -> Metrics.MetricsState -> ObservationHandler -> IO AppState
-initWithPool (sock, adminSock) pool conf loggerState metricsState observer = do
+initWithPool :: SQL.Pool -> AppConfig -> Logger.LoggerState -> Metrics.MetricsState -> ObservationHandler -> IO AppState
+initWithPool pool conf loggerState metricsState observer = do
 
   appState <- AppState pool
     <$> newIORef minimumPgVersion -- assume we're in a supported version when starting, this will be corrected on a later step
@@ -146,8 +130,6 @@ initWithPool (sock, adminSock) pool conf loggerState metricsState observer = do
     <*> myThreadId
     <*> newIORef 0
     <*> newIORef 1
-    <*> pure sock
-    <*> pure adminSock
     <*> pure observer
     <*> JwtCache.init conf observer
     <*> pure loggerState
@@ -166,40 +148,6 @@ initWithPool (sock, adminSock) pool conf loggerState metricsState observer = do
 destroy :: AppState -> IO ()
 destroy = destroyPool
 
-initSockets :: AppConfig -> IO AppSockets
-initSockets AppConfig{..} = do
-  let
-    cfg'usp = configServerUnixSocket
-    cfg'uspm = configServerUnixSocketMode
-    cfg'host = configServerHost
-    cfg'port = configServerPort
-    cfg'adminHost = configAdminServerHost
-    cfg'adminPort = configAdminServerPort
-
-  sock <- case cfg'usp of
-    -- I'm not using `streaming-commons`' bindPath function here because it's not defined for Windows,
-    -- but we need to have runtime error if we try to use it in Windows, not compile time error
-    Just path -> createAndBindDomainSocket path cfg'uspm
-    Nothing -> do
-      (_, sock) <-
-        if cfg'port /= 0
-          then do
-            sock <- bindPortTCP cfg'port (fromString $ T.unpack cfg'host)
-            pure (cfg'port, sock)
-          else do
-            -- explicitly bind to a random port, returning bound port number
-            (num, sock) <- bindRandomPortTCP (fromString $ T.unpack cfg'host)
-            pure (num, sock)
-      pure sock
-
-  adminSock <- case cfg'adminPort of
-    Just adminPort -> do
-      adminSock <- bindPortTCP adminPort (fromString $ T.unpack cfg'adminHost)
-      pure $ Just adminSock
-    Nothing -> pure Nothing
-
-  pure (sock, adminSock)
-
 initPool :: AppConfig -> ObservationHandler -> IO SQL.Pool
 initPool AppConfig{..} observer = do
   SQL.acquire $ SQL.settings
@@ -313,12 +261,6 @@ getTime = stateGetTime
 getJwtCacheState :: AppState -> JwtCacheState
 getJwtCacheState = stateJwtCache
 
-getSocketREST :: AppState -> NS.Socket
-getSocketREST = stateSocketREST
-
-getSocketAdmin :: AppState -> Maybe NS.Socket
-getSocketAdmin = stateSocketAdmin
-
 getMainThreadId :: AppState -> ThreadId
 getMainThreadId = stateMainThreadId