Add support for defining securityContext in cluster spec

[KashifSaadat]

Support adding a securityContext to the Cluster Spec, for example:

apiVersion: mysql.oracle.com/v1alpha1
kind: Cluster
metadata:
  name: test-mysql-db
spec:
  multiMaster: true
  members: 3
  securityContext:
    runAsNonRoot: true
    runAsUser: 27
    fsGroup: 27
  ...

[KashifSaadat]

I've signed and emailed over the OCA earlier today.

[owainlewis]

Thanks @KashifSaadat we will chase up the OCA today and review the PR this week. 👍

[KashifSaadat]

Great, thank you! :)

[owainlewis]

OCA approved. Ready for review.

[prydie]

Change LGTM 👍 .

We may, however, want to consider two things going forward:

• This won't (as it stands) be applied to existing clusters. For that to be the case we'd need to be reconciling the entire StatefulSet or to add specific code to reconcile the PSP in the cluster controller.
• Its becoming clear that people want to be able to modify many similar fields. Grouping them under a .spec.[Pod?]Template field (following the same pattern as StatefulSets / Deployments etc.) probably makes sense. This would be a breaking change we'd want to introduce when moving to v1beta1.

[KashifSaadat]

That's great, thanks for the review and info! Yes that makes sense to have some form of PodTemplateSpec where all those common attributes could be defined and grouped under.