fix: not logging termination unix signals

Under container environments like ECS, it's hard to know when PostgREST
is being terminated.

CHANGELOG.md

@@ -15,6 +15,10 @@ All notable changes to this project will be documented in this file. From versio
 - Add config `client_error_verbosity` to customize error verbosity by @taimoorzaeem in #4088, #3980, #3824
 - Add `Vary` header to responses by @develop7 in #4609
 
+### Fixed
+
+- Fix not logging SIGTERM and SIGINT by @steve-chavez in #4728
+
 ### Changed
 
 - All responses now include a `Vary` header by @develop7 in #4609

src/PostgREST/App.hs

@@ -80,7 +80,7 @@ run appState = do
   AppState.schemaCacheLoader appState -- Loads the initial SchemaCache
   (mainSocket, adminSocket) <- initSockets conf
 
-  Unix.installSignalHandlers (AppState.getMainThreadId appState) (AppState.schemaCacheLoader appState) (AppState.readInDbConfig False appState)
+  Unix.installSignalHandlers observer (AppState.getMainThreadId appState) (AppState.schemaCacheLoader appState) (AppState.readInDbConfig False appState)
 
   Listener.runListener appState
 
@@ -283,4 +283,3 @@ initSockets AppConfig{..} = do
     Nothing -> pure Nothing
 
   pure (sock, adminSock)
-

src/PostgREST/Logger.hs

@@ -228,6 +228,8 @@ observationMessages = \case
     pure "Looked up a JWT in JWT cache"
   JwtCacheEviction ->
     pure "Evicted entry from JWT cache"
+  TerminationUnixSignalObs signal ->
+    pure $ "Received termination unix signal " <> signal
   WarpErrorObs txt ->
     pure $ "Warp server error: " <> txt
   where

src/PostgREST/Observation.hs

@@ -54,6 +54,7 @@ data Observation
   | PoolRequestFullfilled
   | JwtCacheLookup Bool
   | JwtCacheEviction
+  | TerminationUnixSignalObs Text
   | WarpErrorObs Text
 
 data ObsFatalError = ServerAuthError | ServerPgrstBug | ServerError42P05 | ServerError08P01

src/PostgREST/Unix.hs

@@ -11,26 +11,27 @@ import qualified System.Posix.Signals as Signals
 import System.Posix.Types       (FileMode)
 import System.PosixCompat.Files (setFileMode)
 
-import           Data.String      (String)
-import qualified Network.Socket   as NS
+import           Data.String           (String)
+import qualified Network.Socket        as NS
+import qualified PostgREST.Observation as Observation
 import           Protolude
-import           System.Directory (removeFile)
-import           System.IO.Error  (isDoesNotExistError)
+import           System.Directory      (removeFile)
+import           System.IO.Error       (isDoesNotExistError)
 
 -- | Set signal handlers, only for systems with signals
-installSignalHandlers :: ThreadId -> IO () -> IO () -> IO ()
+installSignalHandlers :: Observation.ObservationHandler -> ThreadId -> IO () -> IO () -> IO ()
 #ifndef mingw32_HOST_OS
-installSignalHandlers tid usr1 usr2 = do
+installSignalHandlers observer tid usr1 usr2 = do
   let interrupt = throwTo tid UserInterrupt
-  install Signals.sigINT interrupt
-  install Signals.sigTERM interrupt
+  install Signals.sigINT  $ observer (Observation.TerminationUnixSignalObs "SIGINT") >> interrupt
+  install Signals.sigTERM $ observer (Observation.TerminationUnixSignalObs "SIGTERM") >> interrupt
   install Signals.sigUSR1 usr1
   install Signals.sigUSR2 usr2
   where
     install signal handler =
       void $ Signals.installHandler signal (Signals.Catch handler) Nothing
 #else
-installSignalHandlers _ _ _ = pass
+installSignalHandlers _ _ _ _ = pass
 #endif
 
 -- | Create a unix domain socket and bind it to the given path.

test/io/test_io.py

@@ -127,6 +127,24 @@ def test_graceful_shutdown_waits_for_in_flight_request(defaultenv):
         t.join()
 
 
+def test_termination_unix_signal_logging(defaultenv):
+    "Server logs when handling termination unix signals."
+
+    with run(env=defaultenv) as postgrest:
+        postgrest.process.send_signal(signal.SIGTERM)
+        lines = postgrest.read_stdout(nlines=1)
+        wait_until_exit(postgrest)
+
+    assert any("SIGTERM" in line for line in lines)
+
+    with run(env=defaultenv) as postgrest:
+        postgrest.process.send_signal(signal.SIGINT)
+        lines = postgrest.read_stdout(nlines=1)
+        wait_until_exit(postgrest)
+
+    assert any("SIGINT" in line for line in lines)
+
+
 def test_random_port_bound(defaultenv):
     "PostgREST should bind to a random port when PGRST_SERVER_PORT is 0."