I am starting to convert all of our systems to using upstart to manage our various application processes. One thing that I am constantly missing is the ability to send a different signal to the process on stop or restart events.
For instance, we run our web processes with Unicorn. Unicorn has a great signal handling API. When I want to gracefully reload the process I send the master pid a USR2 signal. To shut them down gracefully I send a QUIT command. TERM (upstart's default stop signal) constitutes an immediate shutdown.
Another example is using Resque. To gracefully shut down a worker I send it the QUIT signal. The TERM signal again causes immediate shutdown, whether the worker's child is forked or not.
Does upstart support custom signals? I can't seem to find it anywhere, which worries me that I'm using the "wrong tool for the job".
Best Answer
Ubuntu 10.04 comes with upstart version 0.6.6 which has the
kill signalandkill timeoutparameters which would configure relevant signal and timeout values. The "reload" signal is hardcoded toSIGHUP.Newer versions of
upstartintroduce thereload signalparameter - see other answers to this question for further detail.