Fix linting `kind: List` metadata

Helm v2 didn't validate that resource names were valid. Helm v3
introduces this check, failing lint checks that were previously
passing.

This PR adds a check to validate metadata for a list of resources if
present, otherwise falling back to previous behavior of validating the
metadata.

Fixes https://github.com/helm/helm/issues/8615

Signed-off-by: Chris Bui <christopher.d.bui@gmail.com>

pkg/lint/rules/template.go

@@ -126,11 +126,17 @@ func Templates(linter *support.Linter, values map[string]interface{}, namespace
 			// Even though K8sYamlStruct only defines a few fields, an error in any other
 			// key will be raised as well
 			err := yaml.Unmarshal([]byte(renderedContent), &yamlStruct)
-
 			// If YAML linting fails, we sill progress. So we don't capture the returned state
 			// on this linter run.
 			linter.RunLinterRule(support.ErrorSev, fpath, validateYamlContent(err))
-			linter.RunLinterRule(support.ErrorSev, fpath, validateMetadataName(&yamlStruct))
+			if isListOfResources(&yamlStruct) {
+				for i, item := range yamlStruct.Items {
+					err := errors.Wrapf(validateMetadataName(&item), "at item index %d", i)
+					linter.RunLinterRule(support.ErrorSev, fpath, err)
+				}
+			} else {
+				linter.RunLinterRule(support.ErrorSev, fpath, validateMetadataName(&yamlStruct))
+			}
 			linter.RunLinterRule(support.ErrorSev, fpath, validateNoDeprecations(&yamlStruct))
 			linter.RunLinterRule(support.ErrorSev, fpath, validateMatchSelector(&yamlStruct, renderedContent))
 		}
@@ -164,13 +170,16 @@ func validateYamlContent(err error) error {
 	return errors.Wrap(err, "unable to parse YAML")
 }
 
-func validateMetadataName(obj *K8sYamlStruct) error {
-	// This will return an error if the characters do not abide by the standard OR if the
-	// name is left empty.
-	if validName.MatchString(obj.Metadata.Name) {
+func isListOfResources(yamlStruct *K8sYamlStruct) bool {
+	return len(yamlStruct.Items) > 0
+}
+
+func validateMetadataName(yamlStruct *K8sYamlStruct) error {
+	if validName.MatchString(yamlStruct.Metadata.Name) {
 		return nil
 	}
-	return fmt.Errorf("object name does not conform to Kubernetes naming requirements: %q", obj.Metadata.Name)
+
+	return fmt.Errorf("object name does not conform to Kubernetes naming requirements: %q", yamlStruct.Metadata.Name)
 }
 
 func validateNoCRDHooks(manifest []byte) error {
@@ -208,6 +217,7 @@ type K8sYamlStruct struct {
 	APIVersion string `json:"apiVersion"`
 	Kind       string
 	Metadata   k8sYamlMetadata
+	Items      []K8sYamlStruct
 }
 
 type k8sYamlMetadata struct {

pkg/lint/rules/template_test.go

@@ -134,6 +134,23 @@ func TestValidateMetadataName(t *testing.T) {
 	}
 }
 
+func TestListOfResources(t *testing.T) {
+	testData := map[string]int{
+		"./testdata/good_list_of_resources": 0,
+		"./testdata/bad_list_of_resources":  2,
+	}
+
+	for testDir, expectedErrs := range testData {
+		linter := support.Linter{ChartDir: testDir}
+		Templates(&linter, values, namespace, strict)
+		res := linter.Messages
+
+		if len(res) != expectedErrs {
+			t.Fatalf("Expected %d error(s) in %s, got %d, %v", expectedErrs, testDir, len(res), res)
+		}
+	}
+}
+
 func TestDeprecatedAPIFails(t *testing.T) {
 	mychart := chart.Chart{
 		Metadata: &chart.Metadata{

pkg/lint/rules/testdata/bad_list_of_resources/Chart.yaml

@@ -0,0 +1,5 @@
+apiVersion: v1
+name: bad list of resources
+description: list of resources testing chart
+version: 199.44.12345-Alpha.1+cafe009
+icon: http://riverrun.io

pkg/lint/rules/testdata/bad_list_of_resources/templates/list_resource.yaml

@@ -0,0 +1,8 @@
+apiVersion: v1
+kind: List
+items:
+  - apiVersion: v1
+    kind: ConfigMap
+    metadata:
+  - apiVersion: v1
+    kind: ConfigMap

pkg/lint/rules/testdata/bad_list_of_resources/values.yaml

@@ -0,0 +1 @@
+name: "bad list of resources"

pkg/lint/rules/testdata/good_list_of_resources/Chart.yaml

@@ -0,0 +1,5 @@
+apiVersion: v1
+name: good list of resources
+description: list of resources testing chart
+version: 199.44.12345-Alpha.1+cafe009
+icon: http://riverrun.io

pkg/lint/rules/testdata/good_list_of_resources/templates/list_resource.yaml

@@ -0,0 +1,11 @@
+apiVersion: v1
+kind: List
+items:
+  - apiVersion: v1
+    kind: ConfigMap
+    metadata:
+      name: config1
+  - apiVersion: v1
+    kind: ConfigMap
+    metadata:
+      name: config2

pkg/lint/rules/testdata/good_list_of_resources/values.yaml

@@ -0,0 +1 @@
+name: "good list of resources"