Re: thoughts on rudimentary dependency handling

From: Laurent Bercot <ska-supervision_at_skarnet.org>
Date: Wed, 07 Jan 2015 12:18:51 +0100

On 07/01/2015 09:16, Luke Diamand wrote:
> One small concern would be that it's not enough to simply signal a
> dependency to be "up" - it needs to be actually running and working
> before you can start the dependent service successfully. To take my
> [least-]favourite example, you can't start autofs until ypbind has
> actually contacted the NIS server.

  Readiness notification is hard: it needs support from the daemon
itself, and most daemons are not written that way.

  Of course, systemd jumped on the opportunity to encourage daemon
authors to use systemd-specific interfaces to provide readiness
notification. Embrace and extend.

  Fortunately, it's not the only way. There's a very simple way
for a daemon to notify the outside world of its readiness: write
something to a descriptor.

  See http://skarnet.org/software/s6/notifywhenup.html

-- 
  Laurent
Received on Wed Jan 07 2015 - 11:18:51 UTC

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