Merge pull request #544 from TiberiuGC/feature/allow-cyclic-references

Allow skipping state validations for resources that support cyclic references

Author: TiberiuGC

pkg/config/field.go

@@ -354,6 +354,20 @@ type ReferencesConfig struct {
 	// Resource mentions the K8s resource which is read to resolve the
 	// reference
 	Resource string `json:"resource"`
+	// SkipResourceStateValidations if true, skips state validations performed during
+	// ResolveReferences step, that ensure the referenced resource exists in AWS and is synced.
+	// This is needed when multiple resources reference each other in a cyclic manner,
+	// as otherwise they will never sync due to circular ResourceReferenceNotSynced errors.
+	//
+	// see: https://github.com/aws-controllers-k8s/community/issues/2119
+	//
+	// N.B. when setting this field to true, the developer is responsible to amend the sdkCreate
+	// and/or sdkUpdate functions of the referencing resource, in order to correctly wait on the
+	// desired state of the referenced resource, before SDK API calls that require the latter.
+	// In the future, we could consider generating this logic, but for now this is a niche use case.
+	//
+	// see: https://github.com/aws-controllers-k8s/ec2-controller/blob/main/pkg/resource/security_group/sdk.go
+	SkipResourceStateValidations bool `json:"skip_resource_state_validations"`
 	// Path refers to the the path of field which should be copied
 	// to resolve the reference
 	Path string `json:"path"`

templates/pkg/resource/references_read_referenced_resource.go.tpl

@@ -28,12 +28,8 @@ func getReferencedResourceState_{{ .FieldConfig.References.Resource }}(
 	if err != nil {
 		return err
 	}
-	var refResourceSynced, refResourceTerminal bool
+	var refResourceTerminal bool
 	for _, cond := range obj.Status.Conditions {
-		if cond.Type == ackv1alpha1.ConditionTypeResourceSynced &&
-			cond.Status == corev1.ConditionTrue {
-			refResourceSynced = true
-		}
 		if cond.Type == ackv1alpha1.ConditionTypeTerminal &&
 			cond.Status == corev1.ConditionTrue {
 			return ackerr.ResourceReferenceTerminalFor(
@@ -46,6 +42,14 @@ func getReferencedResourceState_{{ .FieldConfig.References.Resource }}(
 			"{{ .FieldConfig.References.Resource }}",
 			namespace, name)
 	}
+{{if not .FieldConfig.References.SkipResourceStateValidations -}}
+	var refResourceSynced bool
+	for _, cond := range obj.Status.Conditions {
+		if cond.Type == ackv1alpha1.ConditionTypeResourceSynced &&
+			cond.Status == corev1.ConditionTrue {
+			refResourceSynced = true
+		}
+	}
 	if !refResourceSynced {
 		return ackerr.ResourceReferenceNotSyncedFor(
 			"{{ .FieldConfig.References.Resource }}",
@@ -57,6 +61,7 @@ func getReferencedResourceState_{{ .FieldConfig.References.Resource }}(
 			namespace, name,
 			"{{ .FieldConfig.References.Path }}")
 	}
+{{- end}}
 	return nil
 }
 {{- end -}}