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