Pin a "Logical_Router" to a chassis when the gateway network (external
network) is tunnelled. When the external network is tunnelled, the
"Logical_Router_Port" acting as gateway port is not bound to any
chassis (the network has no physical provider network defined).
In that case, the router is pinned to a chassis instead. A
"HA_Chassis_Group" is created per router. The highest "HA_Chassis" of
this group is assigned to the router. If the gateway port is deleted,
the pinned chassis is removed from the "options" field. If the
router is deleted, the "HA_Chassis_Group" is deleted too.
NOTE: in the a chassis belonging to the router "HA_Chassis_Group"
changes, the list of "HA_Chassis" will be updated in
``ChassisEvent.handle_ha_chassis_group_changes``. However, a
"HA_Chassis_Group" change is handled by OVN, when assiged.
But in this case we are using this artifact, as commented before,
to "manually assign" (from core OVN point of view) the highest
priority "HA_Chassis" to the router (this upcoming funcionality
will be implemented in core OVN). A new follow-up patch will be
pushed to provide HA functionality and update the "HA_Chassis"
assigned to the "Logical_Router" when the chassis list changes.
Partial-Bug: #2052821
Change-Id: I33555fc8a8441149b683ae68f1f10548ffb662a6
25a1809964