add template loading to generator

Kubernetes-commit: 88792d9e72ee48bac2f6c7158531579cc0bc6aca

pkg/explain/v2/explain.go

@@ -37,8 +37,13 @@ func PrintModelDescription(
 	recursive bool,
 	outputFormat string,
 ) error {
+	generator := NewGenerator()
+	if err := registerBuiltinTemplates(generator); err != nil {
+		return fmt.Errorf("error parsing builtin templates. Please file a bug on GitHub: %w", err)
+	}
+
 	return printModelDescriptionWithGenerator(
-		NewGenerator(), fieldsPath, w, client, gvr, recursive, outputFormat)
+		generator, fieldsPath, w, client, gvr, recursive, outputFormat)
 }
 
 // Factored out for testability

pkg/explain/v2/template.go

@@ -0,0 +1,50 @@
+/*
+Copyright 2022 The Kubernetes 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 v2
+
+import (
+	"embed"
+	"path/filepath"
+	"strings"
+)
+
+//go:embed templates/*.tmpl
+var rawBuiltinTemplates embed.FS
+
+func registerBuiltinTemplates(gen Generator) error {
+	files, err := rawBuiltinTemplates.ReadDir("templates")
+	if err != nil {
+		return err
+	}
+
+	for _, entry := range files {
+		contents, err := rawBuiltinTemplates.ReadFile("templates/" + entry.Name())
+		if err != nil {
+			return err
+		}
+
+		err = gen.AddTemplate(
+			strings.TrimSuffix(entry.Name(), filepath.Ext(entry.Name())),
+			string(contents))
+
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

pkg/explain/v2/template_test.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2022 The Kubernetes 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 v2
+
+import (
+	"os"
+	"path"
+	"strings"
+	"testing"
+)
+
+// Ensure that the templates are embededd correctly.
+func TestRegisterBuitinTemplates(t *testing.T) {
+	myGenerator := NewGenerator().(*generator)
+	err := registerBuiltinTemplates(myGenerator)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Show that generator now as a named template for each file in the `templates`
+	// directory.
+	files, err := os.ReadDir("templates")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, templateFile := range files {
+		name := templateFile.Name()
+		ext := path.Ext(name)
+		if ext != "tmpl" {
+			continue
+		}
+
+		name = strings.TrimSuffix(name, ext)
+		if _, ok := myGenerator.templates[name]; !ok {
+			t.Fatalf("missing template: %v", name)
+		}
+	}
+}