1. What is the problem?
In the Tricircle, each tenant is bound to multiple pods,
where it creates various types of resources. However such a binding
relationship should be dynamic instead of static. For instance when
some resources in a pod are exhausted, tenant needs to be bound to a
new pod in same AZ.
2. What is the solution to the problem?
To deal with the above problem, the Tricircle dynamically bind tenants
to pod which has available resources. We call this feature dynamic pod
binding, which is explained in https://review.openstack.org/#/c/306224/
in detail. In this patch, we only try to binds a tenant to a pod
dynamically, when she tries to create a VM.
3. What the features need to be implemented to the Tricircle to realize
the solution?
When a tenant creates a VM, the Tricircle first selects all available
pods for her. Then by filtering and weighing the pods, the Tricircle
selects the most suitable pod for the tenant. Next, the Tricircle query
database for current binding relationship of the tenant. If the tenant
is not bound to any pod, we create a new binding relationship, which
binds the tenant to the selected pod. If the tenant is already bound to
a pod, and the pod is not the pod selected by the Tricircle, we update
current binding relationship, which binds the tenant to a new pod. If
the tenant is already bound to a pod, and the pod is exactly the pod
selected by the Tricircle, the Tricircle does noting.
Change-Id: I3972e6799f78da6ec35be556487f79b1234731b8
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