Add xdiagnose fallback when display-manager fails to start

[Didier Roche-Tolomelli]

Attached patch

[Martin Pitt (pitti)]

+ xdiagnose (>= 3.7),

I don't want systemd to pull in xdiagnose. This will lead to pretty much a disaster on servers :-) This should be left to seeds.

+-Requires=multi-user.target
++Requires=multi-user.target display-manager.service
+ After=multi-user.target
+ Conflicts=rescue.target
+ Wants=display-manager.service

This now seems redundant (Wants+Requires). I think I'm okay with this, as having a graphical target without any DM seems a bit of a corner case. I suppose this is necessary as otherwise OnFailure= wouldn't be called for graphical.target if display-manager.service fails?

I wonder if we could make use of the new ".d/" support in 218 for this. I. e. could the xdiagnose package just ship a /lib/systemd/system/display-manager.service.d/xdiagnose.conf which adds the Requires= and OnFailure=? Then we wouldn't need to teach systemd about this at all, and xdiagnose would be self-contained.

[Didier Roche-Tolomelli (didrocks)]

Right on the dependency, I thought only on the ubuntu destkop case, but yeah, should downgrade to suggests :)

Nice idea on the .d! Definitively doing that then (and so, can close this bug report) :)

Cheers,

[Martin Pitt (pitti)]

Done in https://launchpad.net/ubuntu/+source/xdiagnose/3.7.1

Thanks Didier!