l3-agent checks the HA state of routers when a router is updated.
To ensure that the HA state is only checked on HA routers the following
check is performed: `if router.get('ha') and not is_dvr_only_agent`.
This check should ensure that the check is only performed on
DvrEdgeHaRouter and HaRouter objects.
Unfortunately, there are cases where we have DvrEdgeRouter objects
running on 'dvr_snat' agents. E.g. when deploying a loadbalancer with
neutron-lbaas in a landscape with 6 network nodes and
max_l3_agents_per_router set to 3, it may happen that the loadbalancer
is placed on a network node that does not have a DvrEdgeHaRouter running
on it. In such a case, neutron will deploy a DvrEdgeRouter object on the
network node to serve the loadbalancer, just like it would deploy a
DvrEdgeRouter on a compute node when deploying a VM.
Under such circumstances each update to the router will lead to an
AttributeError, because the DvrEdgeRouter object does not have the
ha_state attribute.
This patch circumvents the issue by doing an additional check on the
router object to ensure that it actually has the ha_state attribute.
Change-Id: I755990324db445efd0ee0b8a9db1f4d7bfb58e26
Closes-Bug: #1755243
8c2dae659a