Openstack upgrade on cinder charm uninstalls nova-compute and neutron agent packages when deployed on the same host

[Przemyslaw Lal]

While performing OpenStack upgrade from bionic-queens to bionic-rocky, cinder charm uninstalled nova-compute, neutron-{dhcp,l3,metadata}-agent and many more packages.

In this environment, cinder is deployed on each compute node (as cinder-volume charm) where nova-compute charm is also deployed.

Simply running:

juju config cinder-volume openstack-origin=cloud:bionic-rocky

Resulted in these actions in apt: [0].

The fatal command that uninstalled nova, neutron and other packages was:

Commandline: apt-get --assume-yes purge python-keystoneclient python-cinder python-memcache python-psycopg2 python-jinja2 python-mysqldb

Charm version: rev 530, latest/stable channel

Bionic, upgrade from "distro" queens to rocky.

I managed to recover by manually reinstalling the removed packages [1].

On one machine this also resulted in the restart of openvswitch-switch and neutron-openvswitch-agent services, resulting in a temporary data plane loss.

[0] https://pastebin.ubuntu.com/p/VXzpMg2V9K/
[1] https://pastebin.ubuntu.com/p/9ndyJQmVFf/

[Alex Kavanagh (ajkavanagh)]

I'm wondering if this is a python2 -> python3 issue; i.e. at queens it is python2, but at rocky the payload is python3. So the cinder charm purges the python2 packages (as indicated in the bug report), but this obviously clobbers nova/neutron due to the common packages.

It's quite a tricky problem as the common packages are needed, but that means that you can't have rocky cinder + queens nova-compute on the same host.

I wonder if nova-compute has been upgraded to rocky as well, that it would have re-installed the packages?

In terms of fixing this issue, we'd probably have to alter the cinder charm code to leave behind the shared packages if it's configured as a volume charm, rather than nuke everything on upgrade.