On 16/06/15 20:42, Roger Leigh wrote:
On 16/06/2015 18:14, Anto wrote:
I was not really sure if script similar to update-rc.d would be relevant
to epoch as the way the runlevel is being managed in epoch is different
from sysvinit. That is why I am looking for other options.
update-rc.d is an *interface* to update service registration by the
packaging system (or the admin). It doesn't matter if you don't use
rc.d/init.d directories; it's just a name resulting from historical
practice. You *do* need to use this mechanism to integrate into the
system. Ignore its name, and just think of it as the public interface
to the init system service management (which is init-system-agnostic).
You can basically ignore the runlevel stuff (it's delegated to the LSB
headers for sysv-rc, so only of historical interest). It basically
has four actions:
- defaults (add [with default runlevels])
- remove
- enable
- disable
So long as you cater for this, that's sufficient. With sysv-rc,
insserv processes the LSB headers for runlevel information and
dependencies; you change them there if you want to adjust them. epoch
can deal with that side of things however it sees fit (it's entirely
an implementation detail)
Thanks a lot Roger for your explanation.
However, I still fail understand how to implement what you explained
without changing anything on any other packages that have daemons to be
managed by epoch. As I mentioned on one of my emails on this thread, the
implementation has always been to include the files specific to the init
systems into those packages. I still can not believe that this is the
only way. Could we not have some kind of man-in-the-middle (I believe
the programming term is API) to be used by all packages including the
init systems that are totally independent, to talk to each other? I am
sorry for those silly questions, but it would be great if you could
explains the reasons why the implementation is always like that and the
impacts if we would divert from that.
I think for me that would also explain why there is no other way to
avoid lock-in to systemd rather than forking Debian.
Just as a side note about epoch in general. It looks like it's using
numerical dependencies. While this does in one sense give control
over ordering to the admin, in reality numerical ordering is a real
PITA. We spent half a decade moving sysv-rc away from that to a
dependency-based system due to all the horrible problems numerical
ordering caused. Everything the numerical ordering does can be
expressed more descriptively via dependencies as in the LSB headers,
since numbers on their own don't describe why it's at that particular
position in relation to the rest, and you quickly run out of "gaps" in
the numbering system as you add more services. The dependency
information in practice gives more control to the admin; so long as
it's possible to dump the ordered list so you can see how it gets the
list.
Regards,
Roger
Cheers,
Anto
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