Validating web hook for synchronous validation

[ash2k]

Expose a validating admission hook endpoint to enable synchronous Bundle validation.

[ash2k]

Perhaps it should be a different binary in the same docker image deployed as a separate Deployment to avoid coupling - if smith is crashing/etc it should not influence the webhook.

[ash2k]

A validation step: prohibit Bundles with resources with annotation DeletionTimestampAnnotation . See #396 (comment)