fix: return an error when we cannot swap the replicaset hashes fixes #…

…2050

rollout/canary.go

@@ -1,6 +1,7 @@
 package rollout
 
 import (
+	"errors"
 	"sort"
 
 	appsv1 "k8s.io/api/apps/v1"
@@ -50,6 +51,11 @@ func (c *rolloutContext) rolloutCanary() error {
 	}
 
 	if err := c.reconcileStableAndCanaryService(); err != nil {
+		// if we cannot reconcile the stable and canary services then
+		// we should not continue to adjust traffic routing
+		if errors.Is(err, DelayServiceSelectorSwapError) {
+			return nil
+		}
 		return err
 	}
 

rollout/canary_test.go

@@ -1262,7 +1262,13 @@ func TestCanarySVCSelectors(t *testing.T) {
 		informers.Start(stopchan)
 		informers.WaitForCacheSync(stopchan)
 		err := rc.reconcileStableAndCanaryService()
-		assert.NoError(t, err, "unable to reconcileStableAndCanaryService")
+		// There is an error returned here because we could not reconcile
+		// unhealthy services.
+		if tc.shouldTargetNewRS {
+			assert.NoError(t, err, "unable to reconcileStableAndCanaryService")
+		} else {
+			assert.Error(t, err, "able to reconcileStableAndCanaryService for unhealthy replicas")
+		}
 		updatedCanarySVC, err := servicesLister.Services(rc.rollout.Namespace).Get(canaryService.Name)
 		assert.NoError(t, err, "unable to get updated canary service")
 		if tc.shouldTargetNewRS {

rollout/service.go

@@ -45,6 +45,14 @@ const (
 }`
 )
 
+type delayServiceSelectorSwapError struct{}
+
+func (e delayServiceSelectorSwapError) Error() string {
+	return "Selectors cannot be swapped yet because not all pods are ready"
+}
+
+var DelayServiceSelectorSwapError = delayServiceSelectorSwapError{}
+
 func generatePatch(service *corev1.Service, newRolloutUniqueLabelValue string, r *v1alpha1.Rollout) string {
 	if _, ok := service.Annotations[v1alpha1.ManagedByRolloutsKey]; !ok {
 		return fmt.Sprintf(switchSelectorAndAddManagedByPatch, r.Name, newRolloutUniqueLabelValue)
@@ -282,7 +290,7 @@ func (c *rolloutContext) ensureSVCTargets(svcName string, rs *appsv1.ReplicaSet,
 		if checkRsAvailability && !replicasetutil.IsReplicaSetAvailable(rs) {
 			logCtx := c.log.WithField(logutil.ServiceKey, svc.Name)
 			logCtx.Infof("delaying service switch from %s to %s: ReplicaSet not fully available", currSelector, desiredSelector)
-			return nil
+			return DelayServiceSelectorSwapError
 		}
 		err = c.switchServiceSelector(svc, desiredSelector, c.rollout)
 		if err != nil {

rollout/service_test.go

@@ -771,7 +771,8 @@ func TestDelayCanaryStableServiceLabelInjection(t *testing.T) {
 		roCtx.stableRS = newReplicaSetWithStatus(ro2, 3, 0)
 
 		err = roCtx.reconcileStableAndCanaryService()
-		assert.NoError(t, err)
+		// an error is returned because we are delaying
+		assert.Equal(t, err, DelayServiceSelectorSwapError)
 		_, canaryInjected := canarySvc.Spec.Selector[v1alpha1.DefaultRolloutUniqueLabelKey]
 		assert.False(t, canaryInjected)
 		_, stableInjected := stableSvc.Spec.Selector[v1alpha1.DefaultRolloutUniqueLabelKey]