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localshred
Asked: 2012-01-14 12:40:43 +0800 CST

How to define different stop/restart signals with upstart

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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".

upstart unicorn ubuntu-10.04

2 Answers

  1. As of upstart v1.10.0 you can define a "reload signal".

    https://launchpad.net/upstart/1.x/1.10.0

    This version is available on ubuntu as of v13.10 ... I used these instructions to upgrade my ec2 instance:

    https://askubuntu.com/questions/302762/upgrading-13-04-to-13-10

    I use rails+puma and do graceful reloads with this directive in my /etc/init/app-1.conf file:

    reload signal SIGUSR2
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  2. Best Answer

    Ubuntu 10.04 comes with upstart version 0.6.6 which has the kill signal and kill timeout parameters which would configure relevant signal and timeout values. The "reload" signal is hardcoded to SIGHUP.

    Newer versions of upstart introduce the reload signal parameter - see other answers to this question for further detail.

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