GenericHostStateSpec

Summary

This blueprint addresses an issue that there are multiple sources for a nova scheduler to make scheduling decision. This blueprint is needed because we do not want the Scheduler to be dependent on Ceilometer. Such a source, for example, Cinder, Ceilometer, and compute node, are referred to as metric source.

Design

The key design is a key-value dictionary that works as an abstraction layer between the scheduler and the metric sources. The key within the layer should be unique across the sources. It is configurable within this layer how to map between each key to a metric source, for example, a number of free VCPUs is mapped to a compute node.