Fix downtime on initial deployment using Istio DestinationRule Subsets

rollout/trafficrouting.go

@@ -194,7 +194,6 @@ func (c *rolloutContext) reconcileTrafficRouting() error {
 			if err != nil {
 				return err
 			}
-
 		} 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()...)
@@ -250,6 +249,16 @@ func (c *rolloutContext) reconcileTrafficRouting() error {
 			}
 		}
 
+		// We need to check if the replicasets are ready here as well if we didn't define any services in the rollout
+		// See: https://github.com/argoproj/argo-rollouts/issues/2507
+		if c.rollout.Spec.Strategy.Canary.CanaryService == "" && c.rollout.Spec.Strategy.Canary.StableService == "" {
+			for _, rs := range c.allRSs {
+				if *rs.Spec.Replicas > 0 && !replicasetutil.IsReplicaSetAvailable(rs) {
+					return fmt.Errorf("delaying destination rule switch: ReplicaSet %s not fully available", rs)
+				}
+			}
+		}
+
 		err = reconciler.UpdateHash(canaryHash, stableHash, weightDestinations...)
 		if err != nil {
 			return err