Neutron packages are not installed on new units

[Facundo Ciccioli]

We are trying to bring back compute nodes back into a currently deployed cloud. After

juju add-unit nova-compute --to ...

we are seeing ovn-chassis fail its certificates-relation-changed hook due to the neutron group not existing. When taking a closer look we notice no neutron packages are installed on the host:

$ dpkg -l | grep neutron
ii python3-neutronclient 1:7.1.1-0ubuntu1 all client API library for Neutron - Python 3.x

We'd expect the charm to install neutron-ovn-metadata-agent at least (which will bring with it neutron-common, etc.)

We don't see any unusual logging on the unit up until the certificates relation hook fails, though we still need to increase logging to DEBUG in the model and retry the unit addition.

This is in the unit's logs though:

2022-09-15 10:36:07 INFO unit.ovn-chassis/78.juju-log server.go:327 nova-compute:238: Invoking reactive handler: reactive/ovn_chassis_charm_handlers.py:81:enable_openstack

Given these flags are set:

 'charm.ovn-chassis.enable-openstack',
 'charm.ovn.chassis.enable-handlers',

we'd expect the enable_openstack handler to install the packages.

This is happening on two fairly different environments:

Env 1:
bionic/ussuri
ovn-chassis charm revision/channel: 14/stable
Juju version: 2.9.26

Env 2:
focal/ussuri
ovn-chassis charm revision/channel: 21/stable
Juju version: 2.9.25
Juju is version

[Facundo Ciccioli (fandanbango)]

Adding field-medium as this is affecting two live clouds already.

[Facundo Ciccioli (fandanbango)]

For completeness, this is a minimal bundle which shows the issue:

series: focal
applications:
  nova-compute:
    charm: cs:nova-compute
    channel: stable
    revision: 337
    num_units: 1
    to:
    - "0"
    constraints: arch=amd64
    storage:
      ephemeral-device: loop,10240M
  ovn-chassis:
    charm: cs:ovn-chassis
    channel: stable
    revision: 21
    options:
      enable-auto-restarts: false
machines:
  "0": {}
relations:
- - ovn-chassis:nova-compute
  - nova-compute:neutron-plugin

The culprit is enable-auto-restarts being false, which sort of makes sense since I figure installing neutron-ovn-metadata-agent would cause some things to restart.

We are trying to work around this by manually installing the package and will post if this is valid.