cloud:bionic-train results in hook failed: "amqp-relation-changed"

[Frank Meeusen]

When deploying from the "cloud:bionic-train" repository I get the juju message `hook failed: "amqp-relation-changed"`.

To recreate this bug outside of our environment I used a vanilla LXD setup with juju.

```
juju bootstrap localhost lxd-controller
juju deploy neutron-dynamic-routing --config openstack-origin="cloud:bionic-train" --config debug=True --config verbose=True
juju deploy rabbitmq-server --config source="cloud:bionic-train"
juju add-relation neutron-dynamic-routing rabbitmq-server
```
Juju status: https://paste.ubuntu.com/p/QTPF52TSzW/

This message does not occur with the queens default repository.
Inside the machine-container I was able to retrieve following logs: https://paste.ubuntu.com/p/MQGzrKdG8m/

These logs learn us that `charm/reactive/dragent_handlers.py` calls upgrade_if_available(), which calls openstack_upgrade_available(), which calls version_compare(). The versions it tries to compare are however '2019.2' and None for package 'neutron-dynamic-routing-common'.

By editing `/var/lib/juju/agents/unit-neutron-dynamic-routing-0/.venv/lib/python3.6/site-packages/charms_openstack/charm/core.py` and hard coding the return of openstack_upgrade_available() to False the charm is able to deploy.

```
diff /var/lib/juju/agents/unit-neutron-dynamic-routing-0/.venv/lib/python3.6/site-packages/charms_openstack/charm/core.py /var/lib/juju/agents/unit-neutron-dynamic-routing-0/.venv/lib/python3.6/site-packages/charms_openstack/charm/core.py.orig
909c909
< return False
---
> return fetch.apt_pkg.version_compare(avail_vers, cur_vers) == 1
```

Status after patching it: https://paste.ubuntu.com/p/fsMfGdzCy8/

I'm not sure where the bug exactly resides, but these are my findings so far. As far as I can see the bgp speaker also becomes active since `openstack network agent list --agent-type bgp` returns State UP and alive.

[Adam Dyess (addyess)]

Reproduced as the submitter stated.

juju deploy neutron-dynamic-routing \
   --config openstack-origin="cloud:bionic-train" \
   --config debug=True \
   --config verbose=True
juju deploy rabbitmq-server --config source="cloud:bionic-train"
juju add-relation neutron-dynamic-routing rabbitmq-server

Updated with crashdump

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/702982

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/702982
Committed: https://git.openstack.org/cgit/openstack/charm-neutron-dynamic-routing/commit/?id=4c7cfc104b4dbbbac91cccf7c75274472d22dcec
Submitter: Zuul
Branch: master

commit 4c7cfc104b4dbbbac91cccf7c75274472d22dcec
Author: Adam Dyess <email address hidden>
Date: Thu Jan 16 14:37:01 2020 -0600

    Closes-Bug: 1859938

    Imports the dragnet module in the reactive handlers module to ensure
    that the BaseOpenStackCharm.singleton is updated with a release_pkt
    attribute

    Change-Id: I99d091c21987d9fafba43754e69c5c3e24fa50ca