Neutron/LBaaS/LoadbalancerInstance

Load balancer instance.

Description

Load balancer instance represents a container object for the load balancer configuration graph. Proposed name for this entity is 'Loadbalancer'.

Rationale:

There are several reasons to introduce this object:

1. Currently the root of object graph is a pool. When we'll move to m:n vip-pool relationship, it will be much more complex to maintain and validate such configurations. Loadbalancer instance is used as an envelope to configuration graph simplifying several tasks such as binding, validation, fetching from server, REST calls dispatching
2. Loadbalancer can be used to bind configuration to a provider, device, agent (host), router

Data model change

Adding Loadbalancer instance is one step towards changing vip-pool relationship from 1:1 to m:n, but at first we'll just introduce Loadbalancer resource to API and make corresponding changes to other objects.

Loadbalancer object:
 * id - uuid, string(36)
 * tenant_id - String(255)
 * Name - String(255)

Proposed change to VIP, Pool, Member objects is to add loadbalancer_id to each of them. Even thought member is related to the certain pool which is related to a balancer, it might save a db query when working with member, so such data duplication might be justified.