Bug#779244: (pre-approval) transitional /etc/insserv/overrides support for Jessie's systemd

[Christian Seiler]

Package: release.debian.org
Severity: normal
X-Debbugs-CC: pkg-systemd-maintainers at lists.alioth.debian.org

Dear release team,

the systemd team would be willing to support parsing
/etc/insserv/overrides in systemd to allow traditional overrides of
init scripts to take effect, but they make doing this conditional on
pre-approval by you (the release team). There is a bug report open on
this topic[0], which the systemd maintainers initially closed as
wontfix, but have reconsidered, due to the fact that systemd currently
does not properly support overriding dependencies in drop-ins (it may
in the future, but definitely not for Jessie, and also upstream's git
currently doesn't yet). For example, if one has a service that has a
dependency After=foo.service, this can only be removed if the service
file is copied verbatim into /etc/systemd/system and the dependency is
removed in the copy. It is not possible to generate a drop-in
(foo.service.d/*.conf) that does that (those only work if one wants to
add dependencies or change/remove non-dependency options). For native
systemd services, this is not an issue, but services for sysvinit
scripts are generated (and only if no native unit with the same name
exists), so overriding dependencies of sysvinit services is non-trivial
(but possible) with Jessie's current version. If systemd would also
parse /etc/insserv/overrides, overriding init script dependencies would
be much easier for administrators. Also note that using
/etc/insserv/overrides to override dependencies was not completely
uncommon in previous Debian versions (mainly Squeeze and Wheezy) and
this could greatly reduce some pain people might feel on upgrades. (It
would certainly help me a lot, even though I know the workaround.)

The systemd maintainers do plan to remove support for this after
Jessie, so this is a transitional measure to ease migration that only
makes sense if included in Jessie.

I wrote a patch that does this, it's attached to the original bug
report, and I've also attached it to this email. One issue with a
previous version of the patch was found and fixed (in case you're
reading the original report). I've used the current version
successfully on a VM for a couple of days now without any issues
arising from this.

I'd like to ask you to consider approving this change, so that one of
the next uploads of systemd for Jessie could include it.

Thank you for considering!

Christian

[0] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=759001
[1]
https://bugs.debian.org/cgi-bin/bugreport.cgi?msg=106;filename=sysv-generator-add-support-for-etc-insserv-overrides.patch;att=1;bug=759001
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