bracket.hs

import Control.Exception
import Control.Concurrent
import System.IO (hSetBuffering, BufferMode(NoBuffering), stdout)

main = do
  hSetBuffering stdout NoBuffering
  bracket (return "ending")
       (\x -> putStrLn x)
       (\_ -> threadDelay 10000000000)

sigterm.hs

import System.Posix.Signals
import Control.Concurrent (threadDelay)
import Control.Concurrent.MVar

termHandler :: MVar () -> Handler
termHandler v = CatchOnce $ do
    putStrLn "Caught SIGTERM"
    putMVar v ()

loop :: MVar () -> IO ()
loop v = do
    putStrLn "Still running"
    threadDelay 1000000
    val <- tryTakeMVar v
    case val of
        Just _ -> putStrLn "Quitting" >> return ()
        Nothing -> loop v

main = do
    v <- newEmptyMVar
    installHandler sigTERM (termHandler v) Nothing
    loop v