Preserve existing namespace when using kubectl set --local

pkg/kubectl/cmd/set/set_env_test.go

@@ -78,6 +78,43 @@ func TestSetEnvLocal(t *testing.T) {
 	}
 }
 
+func TestSetEnvLocalNamespace(t *testing.T) {
+	tf := cmdtesting.NewTestFactory().WithNamespace("test")
+	defer tf.Cleanup()
+
+	tf.Client = &fake.RESTClient{
+		GroupVersion:         schema.GroupVersion{Version: ""},
+		NegotiatedSerializer: scheme.Codecs.WithoutConversion(),
+		Client: fake.CreateHTTPClient(func(req *http.Request) (*http.Response, error) {
+			t.Fatalf("unexpected request: %s %#v\n%#v", req.Method, req.URL, req)
+			return nil, nil
+		}),
+	}
+	tf.ClientConfigVal = &restclient.Config{ContentConfig: restclient.ContentConfig{GroupVersion: &schema.GroupVersion{Version: ""}}}
+	outputFormat := "yaml"
+
+	streams, _, buf, bufErr := genericclioptions.NewTestIOStreams()
+	opts := NewEnvOptions(streams)
+	opts.PrintFlags = genericclioptions.NewPrintFlags("").WithDefaultOutput(outputFormat).WithTypeSetter(scheme.Scheme)
+	opts.FilenameOptions = resource.FilenameOptions{
+		Filenames: []string{"../../../../test/fixtures/pkg/kubectl/cmd/set/namespaced-resource.yaml"},
+	}
+	opts.Local = true
+
+	err := opts.Complete(tf, NewCmdEnv(tf, streams), []string{"env=prod"})
+	assert.NoError(t, err)
+	err = opts.Validate()
+	assert.NoError(t, err)
+	err = opts.RunEnv()
+	assert.NoError(t, err)
+	if bufErr.Len() > 0 {
+		t.Errorf("unexpected error: %s", string(bufErr.String()))
+	}
+	if !strings.Contains(buf.String(), "namespace: existing-ns") {
+		t.Errorf("did not set env: %s", buf.String())
+	}
+}
+
 func TestSetMultiResourcesEnvLocal(t *testing.T) {
 	tf := cmdtesting.NewTestFactory().WithNamespace("test")
 	defer tf.Cleanup()

staging/src/k8s.io/cli-runtime/pkg/resource/visitor.go

@@ -169,7 +169,12 @@ func (i *Info) String() string {
 
 // Namespaced returns true if the object belongs to a namespace
 func (i *Info) Namespaced() bool {
-	return i.Mapping != nil && i.Mapping.Scope.Name() == meta.RESTScopeNameNamespace
+	if i.Mapping != nil {
+		// if we have RESTMapper info, use it
+		return i.Mapping.Scope.Name() == meta.RESTScopeNameNamespace
+	}
+	// otherwise, use the presence of a namespace in the info as an indicator
+	return len(i.Namespace) > 0
 }
 
 // Watch returns server changes to this object after it was retrieved.

test/fixtures/pkg/kubectl/cmd/set/namespaced-resource.yaml

@@ -0,0 +1,17 @@
+apiVersion: v1
+kind: ReplicationController
+metadata:
+  name: namespaced-rc
+  namespace: existing-ns
+spec:
+  replicas: 1
+  selector:
+    app: mock
+  template:
+    metadata:
+      labels:
+        app: mock
+    spec:
+      containers:
+      - name: mock-container
+        image: k8s.gcr.io/pause:3.1