Michał KłeczekandSteve Chavez
8fa26ee865
This change ensures PostgREST starts listening on a server socket only after it loaded the schema cache and is ready to handle requests. It is no longer going to return 503 errors during startup until the schema cache is loaded.
76 lines
3.0 KiB
Haskell
76 lines
3.0 KiB
Haskell
module PostgREST.Admin
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( runAdmin
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) where
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import qualified Data.Aeson as JSON
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import qualified Network.HTTP.Types.Status as HTTP
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import qualified Network.Wai as Wai
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import qualified Network.Wai.Handler.Warp as Warp
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import Control.Monad.Extra (whenJust)
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import Network.Socket hiding (addrFamily)
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import Network.Socket.ByteString
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import PostgREST.AppState (AppState)
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import PostgREST.MediaType (MediaType (..), toContentType)
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import PostgREST.Metrics (metricsToText)
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import PostgREST.Network (resolveSocketToAddress)
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import PostgREST.Observation (Observation (..))
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import qualified PostgREST.AppState as AppState
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import qualified Network.Socket as NS
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import Protolude
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runAdmin :: AppState -> Maybe NS.Socket -> IO (Maybe NS.Socket) -> Warp.Settings -> IO ()
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runAdmin appState maybeAdminSocket getSocketREST settings = do
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whenJust maybeAdminSocket $ \adminSocket -> do
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address <- resolveSocketToAddress adminSocket
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observer $ AdminStartObs address
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void . forkIO $ Warp.runSettingsSocket settings adminSocket adminApp
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where
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adminApp = admin appState getSocketREST
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observer = AppState.getObserver appState
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-- | PostgREST admin application
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admin :: AppState.AppState -> IO (Maybe NS.Socket) -> Wai.Application
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admin appState getSocketREST req respond = do
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isMainAppReachable <- getSocketREST >>= maybe (pure False) (fmap isRight . reachMainApp)
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isLoaded <- AppState.isLoaded appState
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isPending <- AppState.isPending appState
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case Wai.pathInfo req of
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["live"] ->
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respond $ Wai.responseLBS (if isMainAppReachable then HTTP.status200 else HTTP.status500) [] mempty
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["ready"] ->
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let
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status | isPending = HTTP.status503
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| not isMainAppReachable = HTTP.status500
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| isLoaded = HTTP.status200
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| otherwise = HTTP.status500
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in
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respond $ Wai.responseLBS status [] mempty
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["schema_cache"] -> do
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sCache <- AppState.getSchemaCache appState
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respond $ Wai.responseLBS HTTP.status200 [] (maybe mempty JSON.encode sCache)
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["metrics"] -> do
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mets <- metricsToText
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respond $ Wai.responseLBS HTTP.status200 [toContentType MTTextPlain] mets -- Content-Type is required for prometheus compliance
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_ ->
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respond $ Wai.responseLBS HTTP.status404 [] mempty
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-- Try to connect to the main app socket
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-- Note that it doesn't even send a valid HTTP request, we just want to check that the main app is accepting connections
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reachMainApp :: Socket -> IO (Either IOException ())
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reachMainApp appSock = do
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sockAddr <- getSocketName appSock
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sock <- socket (addrFamily sockAddr) Stream defaultProtocol
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try $ do
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connect sock sockAddr
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withSocketsDo $ bracket (pure sock) close sendEmpty
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where
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sendEmpty sock = void $ send sock mempty
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addrFamily (SockAddrInet _ _) = AF_INET
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addrFamily (SockAddrInet6 {}) = AF_INET6
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addrFamily (SockAddrUnix _) = AF_UNIX
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