systemd dependency loop

[Scott Moser]

while testing cloud-init in -proposed for bug 1629797
I found that the changes to cloud-init create a dependency loop for
 google-startup-scripts.service"

I'll attach journalctl output.

I think related is
 https://code.launchpad.net/~philroche/ubuntu/+source/gce-compute-image-packages/+git/gce-compute-image-packages/+merge/311153

The change here seems to me to resolve the issue, and should be safe with new or older cloud-init as cloud-init.target is present everywhere.
Summary is that we just drop 'Wants' of cloud-final.service.
I'm not sure why google-startup-scripts.service would want to make cloud-final.service start. After should be sufficient.

$ diff -u /lib/systemd/system/google-startup-scripts.service.dist /lib/systemd/system/google-startup-scripts.service
--- /lib/systemd/system/google-startup-scripts.service.dist 2016-11-22 03:32:02.385676527 +0000
+++ /lib/systemd/system/google-startup-scripts.service 2016-11-22 03:50:43.139227057 +0000
@@ -3,7 +3,7 @@
 After=local-fs.target network-online.target network.target
 After=google.service rsyslog.service cloud-final.service
 After=multi-user.target
-Wants=local-fs.target network-online.target network.target cloud-final.service
+Wants=local-fs.target network-online.target network.target

 [Service]
 ExecStart=/usr/share/google/run-startup-scripts

Related bugs:
 * bug 1627436: Startup scripts do not run on 1604 images

[Scott Moser (smoser)]

for easier reference, the dependency loop info is:
Nov 22 02:43:11.473124 smfoo2 systemd[1]: cloud-final.service: Found ordering cycle on cloud-final.service/start
Nov 22 02:43:11.473131 smfoo2 systemd[1]: cloud-final.service: Found dependency on multi-user.target/start
Nov 22 02:43:11.473138 smfoo2 systemd[1]: cloud-final.service: Found dependency on google-startup-scripts.service/start
Nov 22 02:43:11.473145 smfoo2 systemd[1]: cloud-final.service: Found dependency on cloud-final.service/start
Nov 22 02:43:11.473152 smfoo2 systemd[1]: cloud-final.service: Breaking ordering cycle by deleting job google-startup-scripts.service/start
Nov 22 02:43:11.473159 smfoo2 systemd[1]: google-startup-scripts.service: Job google-startup-scripts.service/start deleted to break ordering cycle starting with cloud-final.service/start

[Scott Moser (smoser)]

I looked at gce-compute-image-packages_20160930-0ubuntu2 and it's google-startup-scripts.service is simpler, with no references to cloud-init at all, only:

After=local-fs.target network-online.target network.target rsyslog.service
After=google-instance-setup.service google-network-setup.service
Wants=local-fs.target network-online.target network.target

So it seems likely fine to drop the Wants on cloud-final.service (or even other pieces...)

[Scott Moser (smoser)]

I've now marked this incomplete.
I believe it was seen as a result of running a much older image (/ubuntu-os-cloud/ubuntu-1604-xenial-v20160627) and not having updated it, but just adding -proposed and installing cloud-init.

I've ssince tested with a newer image (ubuntu-1604-xenial-v20161115) and not seen this issue.

After installation of cloud-init from proposed we can do

journalctl --full -o --no-pager
$ journalctl --full --no-pager | grep "ordering" || echo no ordering
no ordering

$ journalctl --full --no-pager | grep -i "break" || echo no breakno break

[Launchpad Janitor (janitor)]

[Expired for gce-utils (Ubuntu) because there has been no activity for 60 days.]