Controller should use HEAD if GET is not available (#3530)

v2/internal/reconcilers/arm/azure_generic_arm_reconciler_instance.go

@@ -559,18 +559,35 @@ func (r *azureDeploymentReconcilerInstance) getStatus(ctx context.Context, id st
 	}
 
 	// Get the resource
-	retryAfter, err := r.ARMConnection.Client().GetByID(ctx, id, apiVersion, armStatus)
-	if err != nil {
-		return nil, retryAfter, errors.Wrapf(err, "getting resource with ID: %q", id)
-	}
+	if genruntime.ResourceOperationGet.IsSupportedBy(r.Obj) {
+		var retryAfter time.Duration
+		retryAfter, err = r.ARMConnection.Client().GetByID(ctx, id, apiVersion, armStatus)
+		if err != nil {
+			return nil, retryAfter, errors.Wrapf(err, "getting resource with ID: %q", id)
+		}
+
+		if r.Log.V(Debug).Enabled() {
+			statusBytes, marshalErr := json.Marshal(armStatus)
+			if marshalErr != nil {
+				return nil, zeroDuration, errors.Wrapf(marshalErr, "serializing ARM status to JSON for debugging")
+			}
 
-	if r.Log.V(Debug).Enabled() {
-		statusBytes, marshalErr := json.Marshal(armStatus)
-		if marshalErr != nil {
-			return nil, zeroDuration, errors.Wrapf(marshalErr, "serializing ARM status to JSON for debugging")
+			r.Log.V(Debug).Info("Got ARM status", "status", string(statusBytes))
+		}
+	} else if genruntime.ResourceOperationHead.IsSupportedBy(r.Obj) {
+		var retryAfter time.Duration
+		var exists bool
+		exists, retryAfter, err = r.ARMConnection.Client().CheckExistenceByID(ctx, id, apiVersion)
+		if err != nil {
+			return nil, retryAfter, errors.Wrapf(err, "getting resource with ID: %q", id)
 		}
 
-		r.Log.V(Debug).Info("Got ARM status", "status", string(statusBytes))
+		// We expect the resource to exist
+		if !exists {
+			return nil, retryAfter, errors.Wrapf(err, "getting resource with ID: %q", id)
+		}
+	} else {
+		return nil, zeroDuration, errors.Errorf("resource must support one of GET or HEAD, but it supports neither")
 	}
 
 	// Convert the ARM shape to the Kube shape

v2/pkg/genruntime/base_types.go

@@ -34,6 +34,16 @@ const (
 	ResourceOperationDelete = ResourceOperation("DELETE")
 )
 
+func (o ResourceOperation) IsSupportedBy(obj SupportedResourceOperations) bool {
+	for _, op := range obj.GetSupportedOperations() {
+		if op == o {
+			return true
+		}
+	}
+
+	return false
+}
+
 // TODO: It's weird that this is isn't with the other annotations
 // TODO: Should we move them all here (so they're exported?) Or shold we move them
 // TODO: to serviceoperator-internal.azure.com to signify they are internal?

v2/pkg/genruntime/kubernetes_resource.go

@@ -18,10 +18,17 @@ type ARMOwned interface {
 	Owner() *ResourceReference
 }
 
+type SupportedResourceOperations interface {
+
+	// GetSupportedOperations gets the set of supported resource operations
+	GetSupportedOperations() []ResourceOperation
+}
+
 // KubernetesResource is an Azure resource. This interface contains the common set of
 // methods that apply to all ASO ARM resources.
 type KubernetesResource interface {
 	ARMOwned
+	SupportedResourceOperations
 
 	// TODO: I think we need this?
 	// KnownOwner() *KnownResourceReference
@@ -36,9 +43,6 @@ type KubernetesResource interface {
 	// GetResourceScope returns the ResourceScope of the resource.
 	GetResourceScope() ResourceScope
 
-	// GetSupportedOperations gets the set of supported resource operations
-	GetSupportedOperations() []ResourceOperation
-
 	// Some types, but not all, have a corresponding:
 	// 	SetAzureName(name string)
 	// They do not if the name must be a fixed value (like 'default').