fix(helm): respect resource policy on ungrade

Don't delete a resource on upgrade if it is annotated with
helm.io/resource-policy=keep. This can cause data loss for users
if the annotation is ignored(e.g. for a PVC)

Close #7677

Signed-off-by: Dong Gang <dong.gang@daocloud.io>

pkg/kube/client.go

@@ -21,6 +21,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"k8s.io/apimachinery/pkg/api/meta"
 	"strings"
 	"sync"
 	"time"
@@ -50,6 +51,8 @@ import (
 // ErrNoObjectsVisited indicates that during a visit operation, no matching objects were found.
 var ErrNoObjectsVisited = errors.New("no objects visited")
 
+var metadataAccessor = meta.NewAccessor()
+
 // Client represents a client capable of communicating with the Kubernetes API.
 type Client struct {
 	Factory Factory
@@ -210,6 +213,19 @@ func (c *Client) Update(original, target ResourceList, force bool) (*Result, err
 
 	for _, info := range original.Difference(target) {
 		c.Log("Deleting %q in %s...", info.Name, info.Namespace)
+
+		if err := info.Get(); err != nil {
+			c.Log("Unable to get obj %q, err: %s", info.Name, err)
+		}
+		annotations, err := metadataAccessor.Annotations(info.Object)
+		if err != nil {
+			c.Log("Unable to get annotations on %q, err: %s", info.Name, err)
+		}
+		if annotations != nil && annotations[ResourcePolicyAnno] == KeepPolicy {
+			c.Log("Skipping delete of %q due to annotation [%s=%s]", info.Name, ResourcePolicyAnno, KeepPolicy)
+			continue
+		}
+
 		res.Deleted = append(res.Deleted, info)
 		if err := deleteResource(info); err != nil {
 			if apierrors.IsNotFound(err) {

pkg/kube/resource_policy.go

@@ -0,0 +1,26 @@
+/*
+Copyright The Helm Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kube // import "helm.sh/helm/v3/pkg/kube"
+
+// ResourcePolicyAnno is the annotation name for a resource policy
+const ResourcePolicyAnno = "helm.sh/resource-policy"
+
+// KeepPolicy is the resource policy type for keep
+//
+// This resource policy type allows resources to skip being deleted
+//   during an uninstallRelease action.
+const KeepPolicy = "keep"