add basic ARCHITECTURE.md (#2503)

* refactor: move ApiRequest a top-level module * refactor: rename DbStructure to SchemaCache * refactor: GucHeader inside Response * refactor: admin app to Workers
2022-10-10 11:24:45 -05:00
parent e4b98d51be
commit 0fbb116dd2
35 changed files with 451 additions and 385 deletions
@@ -1,74 +0,0 @@
-{-# LANGUAGE RecordWildCards #-}
-module PostgREST.Admin
-  ( postgrestAdmin
-  ) where
-
-import qualified Data.Text as T
-
-import Network.Socket
-import Network.Socket.ByteString
-
-import qualified Network.HTTP.Types.Status as HTTP
-import qualified Network.Wai               as Wai
-
-import qualified Hasql.Session as SQL
-
-import qualified PostgREST.AppState as AppState
-import           PostgREST.Config   (AppConfig (..))
-
-import Protolude
-
-- | PostgREST admin application
-postgrestAdmin :: AppState.AppState -> AppConfig -> Wai.Application
-postgrestAdmin appState appConfig req respond  = do
-  isMainAppReachable  <- any isRight <$> reachMainApp appConfig
-  isSchemaCacheLoaded <- isJust <$> AppState.getDbStructure appState
-  isConnectionUp      <-
-    if configDbChannelEnabled appConfig
-      then AppState.getIsListenerOn appState
-      else isRight <$> AppState.usePool appState (SQL.sql "SELECT 1")
-
-  case Wai.pathInfo req of
-    ["ready"] ->
-      respond $ Wai.responseLBS (if isMainAppReachable && isConnectionUp && isSchemaCacheLoaded then HTTP.status200 else HTTP.status503) [] mempty
-    ["live"] ->
-      respond $ Wai.responseLBS (if isMainAppReachable then HTTP.status200 else HTTP.status503) [] mempty
-    _ ->
-      respond $ Wai.responseLBS HTTP.status404 [] mempty
-
-- Try to connect to the main app socket
-- Note that it doesn't even send a valid HTTP request, we just want to check that the main app is accepting connections
-- The code for resolving the "*4", "!4", "*6", "!6", "*" special values is taken from
-- https://hackage.haskell.org/package/streaming-commons-0.2.2.4/docs/src/Data.Streaming.Network.html#bindPortGenEx
-reachMainApp :: AppConfig -> IO [Either IOException ()]
-reachMainApp AppConfig{..} =
-  case configServerUnixSocket of
-    Just path ->  do
-      sock <- socket AF_UNIX Stream 0
-      (:[]) <$> try (do
-        connect sock $ SockAddrUnix path
-        withSocketsDo $ bracket (pure sock) close sendEmpty)
-    Nothing -> do
-      let
-        host | configServerHost `elem` ["*4", "!4", "*6", "!6", "*"] = Nothing
-             | otherwise                                             = Just configServerHost
-        filterAddrs xs =
-          case configServerHost of
-              "*4" -> ipv4Addrs xs ++ ipv6Addrs xs
-              "!4" -> ipv4Addrs xs
-              "*6" -> ipv6Addrs xs ++ ipv4Addrs xs
-              "!6" -> ipv6Addrs xs
-              _    -> xs
-        ipv4Addrs = filter ((/=) AF_INET6 . addrFamily)
-        ipv6Addrs = filter ((==) AF_INET6 . addrFamily)
-
-      addrs <- getAddrInfo (Just $ defaultHints { addrSocketType = Stream }) (T.unpack <$> host) (Just . show $ configServerPort)
-      tryAddr `traverse` filterAddrs addrs
-  where
-    sendEmpty sock = void $ send sock mempty
-    tryAddr :: AddrInfo -> IO (Either IOException ())
-    tryAddr addr = do
-      sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
-      try $ do
-        connect sock $ addrAddress addr
-        withSocketsDo $ bracket (pure sock) close sendEmpty