A transient read error can restart the health deadline of a resource

Behavior#

When the observer cannot read a resource (a transient error, NotFound or a mapping error), it sets the state Unknown and writes no firstUnhealthy time for that resource.

Effect#

The time at which the resource became unhealthy can be lost. The deadline then counts again from a later time, so Degraded, and a rollout failure, can come later than spec.healthAssessment.deadline.

Workaround#

None known.

Fix direction#

Keep the stored firstUnhealthy time when the state is Unknown.