init script generators ( was: Re: proper handling of communication channels in debian)

[Dan Ritter]

On Wed, May 02, 2007 at 07:37:21PM +0200, Sven Mueller wrote:
> Finally, even with all that information available inside a Debian
> package, this would still leave one question unanswered: Who triggers
> init script generation? If a daemon package does so in postinst: How do
> I switch to a different init system? If the init system does it in
> postinst: What happens to additional daemons installed later on? If they
> get regenerated during system start: How much penalty does that cause?
> Currently I think the route to go is to provide a command to daemon
> packages? postinst that (re)generates only the needed scripts for that
> package and have a command used in an init system?s postinst which
> regenerates all of them. That should do. Regenerating during boot would
> most likely take too much time and has other problems, too, like the
> availability of a writeable filesystem to store the generated scripts.

May I paraphrase?

Each daemon package, in postinst, calls
/usr/sbin/update-initsystem

Each init system provides a /usr/sbin/update-initsystem which can read
the common hint format and generate the specific scripts it likes.

When switching from one init system to another, install the new
update-initsystem, find the packages owning the files in /etc/init.d/*,
and have them each do a new postinst.

So: a new package will get the current initsystem, a switch of
initsystems takes some time but is not difficult, and nothing
needs to be regenerated at boot time.

As a systems administrator, I like this. It's not any harder to
understand than update-rc.d

-dsr-

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