Unifies haproxy reference implementation to make common agent based plugin driver
which is suitable for all vendors who wants to use async mechanism.
- Agent API as well as device driver API changed to handle
loadbalancer objects individually;
- Agent loads device drivers according to config;
- LogicalDeviceCache class was removed from agent as it was used only
as a list - to put and remove entries ant check whether entry is in or not.
It was replaced with instance_mapping dict in agent to store known instances and
corresponding device_drivers;
- Agent reports which device drivers are supported (needs for scheduling on plugin side);
- Agent-to-plugin API was extended to provide an ability for agent to update
statuses of pools/vips/members/health_monitors;
- Vendor should only implement device driver; plugin driver just needs
to inherit AgentBasedPluginDriver and override device_driver member;
- This patch doesn't move files to make review easier;
all rename/replace will be done in a subsequent patch;
DocImpact
NOTE: Since the change in the agent RPC API is backward-incompatible
(major RPC version change), LBaaS server-agent communications will be
completely broken until both sides are upgraded so users will be unable to
create new or update existing HAProxy loadbalancer instances during upgrade
Implements blueprint lbaas-common-agent-driver
Change-Id: I9fd90a1321611d202ef838681273081fa6c1686a
916d97b5d6