Bug#992711: debhelper: Please provide backport for bullseye

[Niels Thykier]

Michael Biebl:
> Hi Niels
> 
> Am 23.08.21 um 08:19 schrieb Niels Thykier:
>> [...]
> 
> systemd in buster (v241) does support reading unit files from
> /usr/lib/systemd/system (see systemd-analyze unit-paths).
> The changes to init-system-helpers (namely update-rc.d) to also consider
> unit files in /usr/lib/systemd/system was added in 1.58, i.e. is
> currently only available in bullseye.
> 
> This code path in update-rc.d is only used for older compat levels
> though. Newer debhelper versions disentangled dh_installinit and
> dh_installsystemd and we don't use update-rc.d if
> --skip-systemd-native is used, see commit
> cba2a8a6ea64773e61ab41c218853ee729656650 in debhelper.
> 

Thanks for the analysis. :)

> Also, the code in update-rc.d is only a fallback when the "real"
> systemctl is not available to create the enablement symlinks.
> 
> If we hit this code path and update-rc.d does not find the .service
> file, it silently skips the enablement of the service. The package
> should still install successfully.
> 
> So is it safe? I'd say reasonably so.
> 

My reptile brain reaction to this is that it smells like "fails to
install correctly and failing to declare to do so" if we do not enable a
system when we should have.

I get that most installations that do not have systemd are unlikely to
switch to systemd later but I do want it to "just work(tm)".

> Question is, if we should start moving unit files in
> bullseye(-backports) where everything is installed in /lib from a
> consistency PoV.
> 
> Regards,
> Michael
> 

That is the crux of this request.  The backport was requested to ensure
consistency between bullseye and buster builds (see the OP for details;
I omitted them in my forward to you as I thought they were irrelevant to
my question).  Personally, it is easier for me if both cases use the
same path but only if works for -backports as well.  If we are not
certain it is safe, then I will look at using /lib for -backports even
if it means I cannot comply with this request.

Thanks,
~Niels