This patch implements the proposed solution from LP #2024205 where upon
a Neutron being killed, it could trigger the deletion of the entries
from the ovn_hash_ring table that matches the server hostname. When
this happens on all controllers this could lead to the ovn_hash_ring
being rendered empty which will result in ML2/OVN not processing any
OVSDB events.
Instead of removing the nodes from the ovn_hash_ring table at exit, this
patch changes the code to just mark them as offline instead. That way,
the nodes will remain registered in the table and the heartbeat thread
will set them as online again on the next beat. If the service is
stopped properly there won't be any heartbeat anymore and the nodes will
be seeing as offline by the Hash Ring Manager (same as if they were
deleted).
For more info see LP #2024205.
Closes-Bug: #2024205
Change-Id: I052841c87651773c4988fcf39f9f978094297704
Signed-off-by: Lucas Alvares Gomes <lucasagomes@gmail.com>
f2e3ab3805