Configurable scheduler

[kragniz]

Fixes #235

This allows users to configure the scheduler for pods created via navigator's statefulsets. It's a fairly simple passthrough of the value to the statefulset spec.

There are two options exposed, one in the cluster spec, and the other in the nodepool spec. The nodepool value takes precedent, falling back to the cluster value if it is defined, then the default scheduler.

For example, these (simplified) are equivalent:

kind: "CassandraCluster"              
metadata:                             
  name: "example"                    
spec:                                 
  nodePools:                          
  - name: "ringnodes-1"        
    schedulerName: "fancy-scheduler"
  - name: "ringnodes-2"        
    schedulerName: "fancy-scheduler"

kind: "CassandraCluster"              
metadata:                             
  name: "example"                    
spec:                                 
  schedulerName: "fancy-scheduler"              
  nodePools:                          
  - name: "ringnodes-1"        
  - name: "ringnodes-2"        

Allow configuring scheduler

[jetstack-ci-bot]

@kragniz PR needs rebase

[munnerz]

I'm not convinced of the benefit of allowing default schedulername on the cluster. What if you change the default schedulername and then add another nodepool. I'd expect the current nodepools to also adopt the new default, but they'll be left with the original default.

This is a good point - we need to be careful with how we validate changes if we have this top level field. Perhaps we can remove it for now, and in future add it if required?

[kragniz]

Yep, makes sense to me. I'll remove in the next patchset

[jetstack-ci-bot]

@kragniz PR needs rebase

[kragniz]

I've made the update validation for nodePools a whitelist of changes in #283, so with those patches SchedulerName will not be mutable.

[jetstack-bot]

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[jetstack-ci-bot]

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[jetstack-ci-bot]

Automatic merge from submit-queue.