runNagiosPlugin can miss some exceptions

[ip1981]

This approach does not catch all exceptions, e. g. when a state include some pure code which can throw exceptions, e. i. the state is evaluated afterrunNagiosPlugin' runs:

-- | Execute a Nagios check. The program will terminate at the check's
--   completion. A default status will provided if none is given.
runNagiosPlugin :: NagiosPlugin a -> IO ()
runNagiosPlugin check = do
    (_, st) <- runNagiosPlugin' $ E.catch check panic
    finishWith st
  where
    panic :: E.SomeException -> NagiosPlugin a
    panic = liftIO . finishWith . panicState

I had to use something like this (plugin :: IO (NagiosPlugin ()))

(plugin `catch` critical >>= runNagiosPlugin) `catch` foo
-- ...
critical :: SomeException -> IO (NagiosPlugin ())
critical = return . addResult Critical . T.pack . displayException
-- ...
foo :: MyError -> IO ()
foo e = critical (toException e) >>= runNagiosPlugin

Note that foo cannot catch all exceptions. otherwise it would catch ExitCode as well.

It's a kind of feature, not a bug :-)

[olorin]

Thanks for the report. Could probably work around this by strictly evaluating the result, will have a look later this week.