systemd: start coreos-installer service after systemd-resolved

[dustymabe]

If the system is configured to use systemd-resolved (i.e.
systemd-resolved is enabled) then start coreos-installer after
systemd-resolved. Otherwise we get race conditions where
coreos-installer starts before resolved is up and we get errors like:

         Starting Network Name Resolution...
[  OK  ] Finished Network Manager Wait Online.
[  OK  ] Reached target Network is Online.
         Starting CoreOS Installer...
[   12.949935] coreos-installer-service[889]: coreos-installer install /dev/sda --ignition-url https://dustymabe.fedorapeople.org/user-systemd.ign --insecure-ignition
[   13.007728] coreos-installer-service[907]: Error: parsing arguments
[   13.008549] coreos-installer-service[907]: Caused by: downloading source Ignition config https://dustymabe.fedorapeople.org/user-systemd.ign
[   13.009746] coreos-installer-service[907]: Caused by: sending request for 'https://dustymabe.fedorapeople.org/user-systemd.ign'                                                                                                           [   13.011136] coreos-installer-service[907]: Caused by: error sending request for url (https://dustymabe.fedorapeople.org/user-systemd.ign): error trying to connect: dns error: failed to lookup address information: Temporary failure in
name resolution                                                                                                                                                                                                                              [   13.013407] coreos-installer-service[907]: Caused by: error trying to connect: dns error: failed to lookup address information: Temporary failure in name resolution
[   13.015006] coreos-installer-service[907]: Caused by: dns error: failed to lookup address information: Temporary failure in name resolution
[   13.016399] coreos-installer-service[907]: Caused by: failed to lookup address information: Temporary failure in name resolution
[FAILED] Failed to start CoreOS Installer.

[jlebon]

I guess one alternative/parallel thing which would also help with this is retrying fetches, which is something that has come up as well in the past.

[bgilbert]

Yeah, if we need to hardcode knowledge of systemd-resolved, I'd view that as a temporary workaround pending #283. @dustymabe, could you add a comment referencing that issue?

[dustymabe]

Yeah, if we need to hardcode knowledge of systemd-resolved, I'd view that as a temporary workaround pending #283. @dustymabe, could you add a comment referencing that issue?

Does #390 look good?

[bgilbert]

Yup, thanks!