fix: remove condition where header routes can stay directed at empty …

…service in preemption

Signed-off-by: Dylan Schlager <dylan.schlager@lattice.com>

rollout/trafficrouting.go

@@ -198,6 +198,15 @@ func (c *rolloutContext) reconcileTrafficRouting() error {
 		} else if c.newRS == nil || c.newRS.Status.AvailableReplicas == 0 {
 			// when newRS is not available or replicas num is 0. never weight to canary
 			weightDestinations = append(weightDestinations, c.calculateWeightDestinationsFromExperiment()...)
+			// If a user changes their mind in the middle of an V1 -> V2 update, and then applies a V3
+			// there might have been a V2 ReplicaSet that was scaled up, but is now defunct.
+			// During the V2 rollout, managed routes could have been setup and would continue
+			// to direct traffic to the canary service which is now in front of 0 available replicas.
+			// We want to remove these managed routes alongside the safety here of never weighting to the canary.
+			err := reconciler.RemoveManagedRoutes()
+			if err != nil {
+				return err
+			}
 		} else if c.rollout.Status.PromoteFull {
 			// on a promote full, desired stable weight should be 0 (100% to canary),
 			// But we can only increase canary weight according to available replica counts of the canary.