Add preconditions

Signed-off-by: wxdao <waxiadao@gmail.com>

pkg/kube/client.go

@@ -41,6 +41,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/jsonmergepatch"
+	"k8s.io/apimachinery/pkg/util/mergepatch"
 	"k8s.io/apimachinery/pkg/util/strategicpatch"
 	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
@@ -454,7 +455,13 @@ func createPatch(target *resource.Info, current runtime.Object) ([]byte, types.P
 
 	if isUnstructured || isCRD {
 		// fall back to generic JSON merge patch
-		patch, err := jsonmergepatch.CreateThreeWayJSONMergePatch(oldData, newData, currentData)
+		// from https://github.com/kubernetes/kubectl/blob/b83b2ec7d15f286720bccf7872b5c72372cb8e80/pkg/cmd/apply/patcher.go#L129
+		preconditions := []mergepatch.PreconditionFunc{mergepatch.RequireKeyUnchanged("apiVersion"),
+			mergepatch.RequireKeyUnchanged("kind"), mergepatch.RequireMetadataKeyUnchanged("name")}
+		patch, err := jsonmergepatch.CreateThreeWayJSONMergePatch(oldData, newData, currentData, preconditions...)
+		if err != nil && mergepatch.IsPreconditionFailed(err) {
+			err = fmt.Errorf("%s", "At least one of apiVersion, kind and name was changed")
+		}
 		return patch, types.MergePatchType, err
 	}