Attempting to deploy cs:nova-compute with virt-type: lxd fails due to missing python3-nova-lxd package

[Fabio Augusto Miranda Martins]

If you are deploying Openstack >= Rocky with virt-type set to LXD, the installation of nova-compute units will fail with the following error:

2020-04-09 16:44:12 DEBUG install E: Unable to locate package python3-nova-lxd
2020-04-09 16:44:12 DEBUG install Traceback (most recent call last):
2020-04-09 16:44:12 DEBUG install File "/var/lib/juju/agents/unit-nova-compute-lxd-0/charm/hooks/install.real", line 765, in <module>
2020-04-09 16:44:12 DEBUG install main()
2020-04-09 16:44:12 DEBUG install File "/var/lib/juju/agents/unit-nova-compute-lxd-0/charm/hooks/install.real", line 758, in main
2020-04-09 16:44:12 DEBUG install hooks.execute(sys.argv)
2020-04-09 16:44:12 DEBUG install File "/var/lib/juju/agents/unit-nova-compute-lxd-0/charm/hooks/charmhelpers/core/hookenv.py", line 934, in execute
2020-04-09 16:44:12 DEBUG install self._hooks[hook_name]()
2020-04-09 16:44:12 DEBUG install File "/var/lib/juju/agents/unit-nova-compute-lxd-0/charm/hooks/charmhelpers/contrib/hardening/harden.py", line 93, in _harden_inner2
2020-04-09 16:44:12 DEBUG install return f(*args, **kwargs)
2020-04-09 16:44:12 DEBUG install File "/var/lib/juju/agents/unit-nova-compute-lxd-0/charm/hooks/install.real", line 160, in install
2020-04-09 16:44:12 DEBUG install apt_install(determine_packages(), fatal=True)
2020-04-09 16:44:12 DEBUG install File "/var/lib/juju/agents/unit-nova-compute-lxd-0/charm/hooks/charmhelpers/fetch/ubuntu.py", line 276, in apt_install
2020-04-09 16:44:12 DEBUG install _run_apt_command(cmd, fatal)
2020-04-09 16:44:12 DEBUG install File "/var/lib/juju/agents/unit-nova-compute-lxd-0/charm/hooks/charmhelpers/fetch/ubuntu.py", line 770, in _run_apt_command
2020-04-09 16:44:12 DEBUG install retry_message="Couldn't acquire DPKG lock")
2020-04-09 16:44:12 DEBUG install File "/var/lib/juju/agents/unit-nova-compute-lxd-0/charm/hooks/charmhelpers/fetch/ubuntu.py", line 748, in _run_with_retries
2020-04-09 16:44:12 DEBUG install result = subprocess.check_call(cmd, env=env)
2020-04-09 16:44:12 DEBUG install File "/usr/lib/python3.6/subprocess.py", line 311, in check_call
2020-04-09 16:44:12 DEBUG install raise CalledProcessError(retcode, cmd)
2020-04-09 16:44:12 DEBUG install subprocess.CalledProcessError: Command '['apt-get', '--assume-yes', '--option=Dpkg::Options::=--force-confold', 'install', 'nova-compute', 'genisoimage', 'librbd1', 'xfsprogs', 'nfs-common', 'open-iscsi', 'nova-compute-lxd', 'python3-nova', 'python3-memcache', 'python3-rados', 'python3-rbd', 'python3-nova-lxd']' returned non-zero exit status 100.

This is because a commit [1] has added the following snippet:

    if cmp_release >= 'rocky':
        packages = [p for p in packages if not p.startswith('python-')]
        packages.extend(PY3_PACKAGES)
        if virt_type == 'lxd':
            packages.append('python3-nova-lxd')

However, python3-nova-lxd is only available in Disco:

$ rmadison python3-nova-lxd
 python3-nova-lxd | 19.0.0-0ubuntu1 | disco | all

So, deploying >= Rocky + Bionic with virt-type lxd fails due to that missing package.

[1] https://github.com/openstack/charm-nova-compute/commit/7f15c2f5ce230ec3d1724d924a164e6a49b8584a