* Add smart handling of selectors in webhooks
This is an alternative fix for #1590. Instead of arbitrarily adding a label from a different project to avoid the reconcilers racing, this adds "smart" handling of the selectors in that labels not inside the knative.dev domain are plainly ignored and our own selectors are added additively.
* Fix formatting
* Fix missing variable usage
* include a filter on control plane namespaces for defaulting and validation webhooks from knative/pkg
* Update unit tests to include control-plane
* adding a comment to explain why we are adding 'control-plane' to the webhook config
* Use two lane queue instead of the regular workqueue
- we need to poll for len in the webhook tests because we have async propagation now, and check at the wrong time will be not correct.
- otherwise just a drop in replacement.
* update test
* cmt
* tests hardened
* Allows for webhooks to exclude certain namspaces
Added a namespaces selector to the mutating webhook configuration which
allows for excluding namespaces from the webhook
Fixes#1379
* Updated skipWebhooks key to skip-webhooks for defaulting and validating
webhooks
* Updated table tests with new label
* Updated key name to webhooks.knative.dev/exclude
By combining our validation logic into our mutating webhook we were previously allowing for mutating webhooks evaluated after our own to modify our resources into invalid shapes. There are no guarantees around ordering of mutating webhooks (that I could find), so the only way to remedy this properly is to split apart the two into separate webhook configurations:
- `defaulting`: which runs during the mutating admission webhook phase
- `validation`: which runs during the validating admission webhook phase.
The diagram in [this post](https://kubernetes.io/blog/2019/03/21/a-guide-to-kubernetes-admission-controllers/) is very helpful in illustrating the flow of webhooks.
Fixes: https://github.com/knative/pkg/issues/847
NovaHe
Markus Thömmes
Lionel Villard
Victor Agababov
Scott Nichols
Matt Moore
Dave Protasowski
Mike Petersen