Blazar allows reserving Ironic nodes in error/maintenance state

[Jason Anderson]

It is currently possible for Blazar to allow Ironic nodes in error states or in maintenance mode to be reserved by users. This is not good behavior, as Nova will ultimately disallow instances on those nodes when they are in this state.

There are existing mechanism in Blazar to detect failure states of resources and update containing leases properly. In the case of Nova Hypervisors, this can both prevent bad resources from being reserved, but also heal leases that happened to have a bad node reserved.

Blazar will likely need to query Ironic state directly, as Nova does not expose any helpful information about the state of Ironic nodes: they are either all marked UP/healthy or DOWN/unhealthy. This is due to the design of Nova's Ironic driver.