On Mon, Apr 14, 2014 at 1:43 AM, Jan Zelený <jzeleny(a)redhat.com> wrote:
1) What if I don't use systemd to start whatever program needs the
updated
data? (might not be a daemon for example)
Right, for say Evolution which runs in a user session, it obviously has
to do any mail format migrations when it starts in the session.
One way to view this is we're making system software behave the same
way user session software always was forced to. And in a modern world
where we have systemd, everything is consistently tracked and logged.
2) Wouldn't that start the migration script every time the daemon
starts?
Doesn't sound like a pretty solution.
There are a few ways around this. The simplest is to keep around a
stamp file. It works a lot better of course if schema migrations are a
builtin function of the service.
Then again I'd say neither of these are good for services which are
actually important - if your servers are dedicated to running
Wordpress, you're probably going to want to manage it more directly and
not out of %post or ExecStartPre.