Make autoscalerRef optional

- use anyOf as a workaround for the openAPI object validation not accepting empty values
- fix #23

artifacts/flagger/crd.yaml

@@ -42,7 +42,9 @@ spec:
                 name:
                   type: string
             autoscalerRef:
-              type: object
+              anyOf:
+                - type: string
+                - type: object
               required: ['apiVersion', 'kind', 'name']
               properties:
                 apiVersion:

charts/flagger/templates/crd.yaml

@@ -43,7 +43,9 @@ spec:
                 name:
                   type: string
             autoscalerRef:
-              type: object
+              anyOf:
+                - type: string
+                - type: object
               required: ['apiVersion', 'kind', 'name']
               properties:
                 apiVersion:
@@ -98,5 +100,4 @@ spec:
                         timeout:
                           type: string
                           pattern: "^[0-9]+(m|s)"
-
 {{- end }}

pkg/apis/flagger/v1alpha3/types.go

@@ -46,7 +46,8 @@ type CanarySpec struct {
 	TargetRef hpav1.CrossVersionObjectReference `json:"targetRef"`
 
 	// reference to autoscaling resource
-	AutoscalerRef hpav1.CrossVersionObjectReference `json:"autoscalerRef"`
+	// +optional
+	AutoscalerRef *hpav1.CrossVersionObjectReference `json:"autoscalerRef,omitempty"`
 
 	// virtual service spec
 	Service CanaryService `json:"service"`

pkg/apis/flagger/v1alpha3/zz_generated.deepcopy.go

@@ -21,6 +21,7 @@ limitations under the License.
 package v1alpha3
 
 import (
+	v1 "k8s.io/api/autoscaling/v1"
 	runtime "k8s.io/apimachinery/pkg/runtime"
 )
 
@@ -159,7 +160,11 @@ func (in *CanaryService) DeepCopy() *CanaryService {
 func (in *CanarySpec) DeepCopyInto(out *CanarySpec) {
 	*out = *in
 	out.TargetRef = in.TargetRef
-	out.AutoscalerRef = in.AutoscalerRef
+	if in.AutoscalerRef != nil {
+		in, out := &in.AutoscalerRef, &out.AutoscalerRef
+		*out = new(v1.CrossVersionObjectReference)
+		**out = **in
+	}
 	in.Service.DeepCopyInto(&out.Service)
 	in.CanaryAnalysis.DeepCopyInto(&out.CanaryAnalysis)
 	if in.ProgressDeadlineSeconds != nil {

pkg/controller/deployer.go

@@ -231,7 +231,7 @@ func (c *CanaryDeployer) Sync(cd *flaggerv1.Canary) error {
 		}
 	}
 
-	if cd.Spec.AutoscalerRef.Kind == "HorizontalPodAutoscaler" {
+	if cd.Spec.AutoscalerRef != nil && cd.Spec.AutoscalerRef.Kind == "HorizontalPodAutoscaler" {
 		if err := c.createPrimaryHpa(cd); err != nil {
 			return fmt.Errorf("creating hpa %s.%s failed: %v", primaryName, cd.Namespace, err)
 		}