Support to deploy zun to multiple compute hosts
Currently, Zun supports a devstack deployment, which assume all-in-one host. However, in reality, it is necessary to deploy multiple zun-compute to multiple compute hosts. This needs an re-design of the sandbox creation and container creation:
1. Zun-api cast a request to zun-compute to create a sandbox
2. Zun-compute return the host where the sandbox was created in (either by calling Nova (nova-docker driver) or creating locally (docker driver))
3. Zun-api cast a request to the sandbox host to create container(s).
4. Zun-compute return after container creation.
Whiteboard
Gerrit topic: https:/
Addressed by: https:/
[WIP]
Addressed by: https:/
Rename compute/api.py to compute/rpcapi.py
Addressed by: https:/
Add 'host' field to container
Addressed by: https:/
Fix incorrect filtering at ZunService dbapi
Addressed by: https:/
Fix the incorrect initialization of context roles
Addressed by: https:/
Add etcd DB backend support for multiple compute env