Currently it is a requirement to have a network node with an l3 agent
running in the dvr_snat mode even for DVR deployments that do not use
SNAT or have a very limited usage of SNAT.
It is not possible to disable snat completely:
https://bugs.launchpad.net/neutron/+bug/1761591
Neutron creates a network:router_centralized_snat port and if it is not
possible to find a dvr_snat agent to schedule it on there are various
side-effects which are not seen at first. For example, Designate stops
creating records for floating IPs and Neutron/Designate integration is,
therefore, not functional.
The Neutron DVR documentation says that dvr_snat should be used on
network nodes. However, there is nothing restricting a DVR deployment
from using dvr_snat l3 agents on every compute node and not having
dedicated network nodes.
This change modifies neutron-openvswitch to optionally enable dvr_snat
l3 agent mode (this includes supporting L3HA routers if enabled). As a
result, it is possible to have deployments without neutron-gateway thus
saving on the amount of required nodes. Care should be taken when a
large amount of L3HA routers is used and using DVR routers without L3HA
is a recommended.
Change-Id: Iad3a64967f91c81312911f6db856ce2271b0e068
Closes-Bug: #1808045
1486c83a1f