contrail-charms: contrail-openstack: support multiple IPs in neutron ContrailPlugin api_server_ip

[Bernhard Koessler]

support support of charm for this fix: https://bugs.launchpad.net/juniperopenstack/+bug/1746151

Currently, the charm configures VIP (if configured, otherwise first unit IP) in Contrail plugin config on neutron unit.

The change should allow to configure the ha endpoints of the contrail-api directly in line with the other config files.

Ideally, there should be a choice of using VIP or the endpoints but the preference should be the endpoints to support HA clusters without the use of a VIP/L2. I assume this can be done by not defining vip in the contrail-controller charm. (VIP could still be used in external hacluster if needed).

Additional note:
- VIP is also configured in /etc/contrail/vnc_api_lib.ini - need to review if VIP can be avoided there as well - TBD
- review other places where VIP is used
e.g. https://github.com/Juniper/contrail-charms/blob/13da977aff7efd67f0e1e7b2f16ecdfc6f445e9c/contrail-agent/hooks/contrail_agent_utils.py#L240

--> this should also use the list of api endpoints directly instead of vip as VIP might not be available on compute nodes due to iptables etc

[Andrey Pavlov (apavlov-e)]

vnc_api also supports list of servers separated by ','

[Andrey Pavlov (apavlov-e)]

code for 4.1 is here https://github.com/Juniper/contrail-controller/blob/R4.1/src/api-lib/vnc_api.py#L337-L338

and similar code present in 4.0 branch

[Andrey Pavlov (apavlov-e)]

another specified place ( https://github.com/Juniper/contrail-charms/blob/13da977aff7efd67f0e1e7b2f16ecdfc6f445e9c/contrail-agent/hooks/contrail_agent_utils.py#L240 )
is used in two operations:
- provide VIP to configs (vnc_api_lib.ini only). it can be switched to use several IP-s
- use the VIP for provision script. it can be re-written to run provision with all IP-s one-be-one until success.

[Andrey Pavlov (apavlov-e)]

several commits are in place ( https://github.com/Juniper/contrail-charms )