Add a flag to switch between patch strategy for unstructured

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

cmd/helm/root.go

@@ -163,6 +163,8 @@ func newRootCmd(actionConfig *action.Configuration, out io.Writer, args []string
 	}
 	actionConfig.RegistryClient = registryClient
 
+	actionConfig.UseThreeWayMergePatchForUnstructured = settings.UseThreeWayMergePatchForUnstructured
+
 	// Add subcommands
 	cmd.AddCommand(
 		// chart commands

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/docker/distribution v2.7.1+incompatible
 	github.com/docker/docker v17.12.0-ce-rc1.0.20200618181300-9dc6525e6118+incompatible
 	github.com/docker/go-units v0.4.0
+	github.com/evanphx/json-patch v4.9.0+incompatible
 	github.com/gobwas/glob v0.2.3
 	github.com/gofrs/flock v0.8.0
 	github.com/gosuri/uitable v0.0.4

pkg/action/action.go

@@ -94,6 +94,10 @@ type Configuration struct {
 	// Capabilities describes the capabilities of the Kubernetes cluster.
 	Capabilities *chartutil.Capabilities
 
+	// UseThreeWayMergePatchForUnstructured controls whether to use three way merge patch
+	// for unstructured (CR, CRD etc.) objects.
+	UseThreeWayMergePatchForUnstructured bool
+
 	Log func(string, ...interface{})
 }
 
@@ -365,6 +369,7 @@ func (cfg *Configuration) recordRelease(r *release.Release) {
 func (cfg *Configuration) Init(getter genericclioptions.RESTClientGetter, namespace, helmDriver string, log DebugLog) error {
 	kc := kube.New(getter)
 	kc.Log = log
+	kc.UseThreeWayMergePatchForUnstructured = cfg.UseThreeWayMergePatchForUnstructured
 
 	lazyClient := &lazyClient{
 		namespace: namespace,

pkg/cli/environment.go

@@ -68,6 +68,9 @@ type EnvSettings struct {
 	PluginsDirectory string
 	// MaxHistory is the max release history maintained.
 	MaxHistory int
+	// UseThreeWayMergePatchForUnstructured controls whether to use three way merge patch
+	// for unstructured (CR, CRD etc.) objects.
+	UseThreeWayMergePatchForUnstructured bool
 }
 
 func New() *EnvSettings {
@@ -86,6 +89,7 @@ func New() *EnvSettings {
 		RepositoryCache:  envOr("HELM_REPOSITORY_CACHE", helmpath.CachePath("repository")),
 	}
 	env.Debug, _ = strconv.ParseBool(os.Getenv("HELM_DEBUG"))
+	env.UseThreeWayMergePatchForUnstructured, _ = strconv.ParseBool(os.Getenv("HELM_USE_THREE_WAY_MERGE_PATCH_FOR_UNSTRUCTURED"))
 
 	// bind to kubernetes config flags
 	env.config = &genericclioptions.ConfigFlags{
@@ -115,6 +119,7 @@ func (s *EnvSettings) AddFlags(fs *pflag.FlagSet) {
 	fs.StringVar(&s.RegistryConfig, "registry-config", s.RegistryConfig, "path to the registry config file")
 	fs.StringVar(&s.RepositoryConfig, "repository-config", s.RepositoryConfig, "path to the file containing repository names and URLs")
 	fs.StringVar(&s.RepositoryCache, "repository-cache", s.RepositoryCache, "path to the file containing cached repository indexes")
+	fs.BoolVar(&s.UseThreeWayMergePatchForUnstructured, "use-three-way-merge-patch-for-unstructured", s.UseThreeWayMergePatchForUnstructured, "use three way merge patch for unstructured (CR, CRD etc.) objects")
 }
 
 func envOr(name, def string) string {

pkg/kube/client.go

@@ -27,6 +27,7 @@ import (
 	"sync"
 	"time"
 
+	jsonpatch "github.com/evanphx/json-patch"
 	"github.com/pkg/errors"
 	batch "k8s.io/api/batch/v1"
 	v1 "k8s.io/api/core/v1"
@@ -69,6 +70,10 @@ type Client struct {
 	// Namespace allows to bypass the kubeconfig file for the choice of the namespace
 	Namespace string
 
+	// UseThreeWayMergePatchForUnstructured controls whether to use three way merge patch
+	// for unstructured (CR, CRD etc.) objects
+	UseThreeWayMergePatchForUnstructured bool
+
 	kubeClient *kubernetes.Clientset
 }
 
@@ -418,7 +423,7 @@ func deleteResource(info *resource.Info) error {
 	return err
 }
 
-func createPatch(target *resource.Info, current runtime.Object) ([]byte, types.PatchType, error) {
+func createPatch(target *resource.Info, current runtime.Object, useThreeWayMergePatchForUnstructured bool) ([]byte, types.PatchType, error) {
 	oldData, err := json.Marshal(current)
 	if err != nil {
 		return nil, types.StrategicMergePatchType, errors.Wrap(err, "serializing current configuration")
@@ -446,7 +451,7 @@ func createPatch(target *resource.Info, current runtime.Object) ([]byte, types.P
 
 	// Unstructured objects, such as CRDs, may not have an not registered error
 	// returned from ConvertToVersion. Anything that's unstructured should
-	// use the jsonmergepatch.CreateThreeWayJSONMergePatch. Strategic Merge Patch is not supported
+	// use generic JSON merge patch. Strategic Merge Patch is not supported
 	// on objects like CRDs.
 	_, isUnstructured := versionedObject.(runtime.Unstructured)
 
@@ -455,6 +460,7 @@ func createPatch(target *resource.Info, current runtime.Object) ([]byte, types.P
 
 	if isUnstructured || isCRD {
 		// fall back to generic JSON merge patch
+		if useThreeWayMergePatchForUnstructured {
 			// 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")}
@@ -464,6 +470,9 @@ func createPatch(target *resource.Info, current runtime.Object) ([]byte, types.P
 			}
 			return patch, types.MergePatchType, err
 		}
+		patch, err := jsonpatch.CreateMergePatch(oldData, newData)
+		return patch, types.MergePatchType, err
+	}
 
 	patchMeta, err := strategicpatch.NewPatchMetaFromStruct(versionedObject)
 	if err != nil {
@@ -490,7 +499,7 @@ func updateResource(c *Client, target *resource.Info, currentObj runtime.Object,
 		}
 		c.Log("Replaced %q with kind %s for kind %s", target.Name, currentObj.GetObjectKind().GroupVersionKind().Kind, kind)
 	} else {
-		patch, patchType, err := createPatch(target, currentObj)
+		patch, patchType, err := createPatch(target, currentObj, c.UseThreeWayMergePatchForUnstructured)
 		if err != nil {
 			return errors.Wrap(err, "failed to create patch")
 		}