Watch/Action on EndpointSlices

[dprotaso]

Long term we want Knative Route to move away from Services with ExternalName. The current idea is to move to EndpointSlices with CNAME address types. This isn't widely available until K8s 1.22 (with CoreDNS 1.8.4)

I believe if Serving did this change it would not work with Kourier. Thus creating a new issue now to get ahead of the curve.

[dprotaso]

cc @markusthoemmes @nak3

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen. Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[dprotaso]

/lifecycle frozen

We'll want this long term