fix(kubectl): explain crds with the same resource name with builtin objects

Kubernetes-commit: 397f107a0886999e0d45955dfe460112edd9ac5e

pkg/cmd/explain/explain.go

@@ -123,19 +123,14 @@ func (o *ExplainOptions) Run(args []string) error {
 	// TODO: After we figured out the new syntax to separate group and resource, allow
 	// the users to use it in explain (kubectl explain <group><syntax><resource>).
 	// Refer to issue #16039 for why we do this. Refer to PR #15808 that used "/" syntax.
-	inModel, fieldsPath, err := explain.SplitAndParseResourceRequest(args[0], o.Mapper)
+	fullySpecifiedGVR, fieldsPath, err := explain.SplitAndParseResourceRequest(args[0], o.Mapper)
 	if err != nil {
 		return err
 	}
 
-	// TODO: We should deduce the group for a resource by discovering the supported resources at server.
-	fullySpecifiedGVR, groupResource := schema.ParseResourceArg(inModel)
-	gvk := schema.GroupVersionKind{}
-	if fullySpecifiedGVR != nil {
-		gvk, _ = o.Mapper.KindFor(*fullySpecifiedGVR)
-	}
+	gvk, _ := o.Mapper.KindFor(fullySpecifiedGVR)
 	if gvk.Empty() {
-		gvk, err = o.Mapper.KindFor(groupResource.WithVersion(""))
+		gvk, err = o.Mapper.KindFor(fullySpecifiedGVR.GroupResource().WithVersion(""))
 		if err != nil {
 			return err
 		}
@@ -151,7 +146,7 @@ func (o *ExplainOptions) Run(args []string) error {
 
 	schema := o.Schema.LookupResource(gvk)
 	if schema == nil {
-		return fmt.Errorf("Couldn't find resource for %q", gvk)
+		return fmt.Errorf("couldn't find resource for %q", gvk)
 	}
 
 	return explain.PrintModelDescription(fieldsPath, o.Out, schema, gvk, recursive)

pkg/explain/explain.go

@@ -20,9 +20,10 @@ import (
 	"io"
 	"strings"
 
+	"k8s.io/kube-openapi/pkg/util/proto"
+
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apimachinery/pkg/runtime/schema"
-	"k8s.io/kube-openapi/pkg/util/proto"
 )
 
 type fieldsPrinter interface {
@@ -43,10 +44,13 @@ func splitDotNotation(model string) (string, []string) {
 }
 
 // SplitAndParseResourceRequest separates the users input into a model and fields
-func SplitAndParseResourceRequest(inResource string, mapper meta.RESTMapper) (string, []string, error) {
+func SplitAndParseResourceRequest(inResource string, mapper meta.RESTMapper) (schema.GroupVersionResource, []string, error) {
 	inResource, fieldsPath := splitDotNotation(inResource)
-	inResource, _ = mapper.ResourceSingularizer(inResource)
-	return inResource, fieldsPath, nil
+	gvr, err := mapper.ResourceFor(schema.GroupVersionResource{Resource: inResource})
+	if err != nil {
+		return schema.GroupVersionResource{}, nil, err
+	}
+	return gvr, fieldsPath, nil
 }
 
 // PrintModelDescription prints the description of a specific model or dot path.

pkg/explain/explain_test.go

@@ -21,37 +21,38 @@ import (
 	"testing"
 
 	"k8s.io/apimachinery/pkg/api/meta/testrestmapper"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/kubectl/pkg/scheme"
 )
 
 func TestSplitAndParseResourceRequest(t *testing.T) {
 	tests := []struct {
 		name       string
-		inresource string
+		inResource string
 
-		expectedInResource string
+		expectedGVR        schema.GroupVersionResource
 		expectedFieldsPath []string
 		expectedErr        bool
 	}{
 		{
 			name:       "no trailing period",
-			inresource: "field1.field2.field3",
+			inResource: "pods.field2.field3",
 
-			expectedInResource: "field1",
+			expectedGVR:        schema.GroupVersionResource{Resource: "pods", Version: "v1"},
 			expectedFieldsPath: []string{"field2", "field3"},
 		},
 		{
 			name:       "trailing period with correct fieldsPath",
-			inresource: "field1.field2.field3.",
+			inResource: "service.field2.field3.",
 
-			expectedInResource: "field1",
+			expectedGVR:        schema.GroupVersionResource{Resource: "services", Version: "v1"},
 			expectedFieldsPath: []string{"field2", "field3"},
 		},
 		{
 			name:       "trailing period with incorrect fieldsPath",
-			inresource: "field1.field2.field3.",
+			inResource: "node.field2.field3.",
 
-			expectedInResource: "field1",
+			expectedGVR:        schema.GroupVersionResource{Resource: "nodes", Version: "v1"},
 			expectedFieldsPath: []string{"field2", "field3", ""},
 			expectedErr:        true,
 		},
@@ -60,13 +61,13 @@ func TestSplitAndParseResourceRequest(t *testing.T) {
 	mapper := testrestmapper.TestOnlyStaticRESTMapper(scheme.Scheme, scheme.Scheme.PrioritizedVersionsAllGroups()...)
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			gotInResource, gotFieldsPath, err := SplitAndParseResourceRequest(tt.inresource, mapper)
+			gotGVR, gotFieldsPath, err := SplitAndParseResourceRequest(tt.inResource, mapper)
 			if err != nil {
 				t.Errorf("unexpected error: %v", err)
 			}
 
-			if !reflect.DeepEqual(tt.expectedInResource, gotInResource) && !tt.expectedErr {
-				t.Errorf("%s: expected inresource: %s, got: %s", tt.name, tt.expectedInResource, gotInResource)
+			if !reflect.DeepEqual(tt.expectedGVR, gotGVR) && !tt.expectedErr {
+				t.Errorf("%s: expected inResource: %s, got: %s", tt.name, tt.expectedGVR, gotGVR)
 			}
 
 			if !reflect.DeepEqual(tt.expectedFieldsPath, gotFieldsPath) && !tt.expectedErr {