refactor resource printer's version handling (to make adding --watch feature easier)

pkg/kubectl/cmd/get.go

@@ -61,22 +61,16 @@ Examples:
 			defaultPrinter, err := f.Printer(cmd, mapping, GetFlagBool(cmd, "no-headers"))
 			checkErr(err)
 
-			printer, versioned, err := kubectl.GetPrinter(outputFormat, templateFile, defaultPrinter)
+			outputVersion := GetFlagString(cmd, "output-version")
+			if len(outputVersion) == 0 {
+				outputVersion = mapping.APIVersion
+			}
+			printer, err := kubectl.GetPrinter(outputVersion, outputFormat, templateFile, defaultPrinter)
 			checkErr(err)
 
 			obj, err := kubectl.NewRESTHelper(client, mapping).Get(namespace, name, labels)
 			checkErr(err)
 
-			if versioned {
-				outputVersion := GetFlagString(cmd, "output-version")
-				if len(outputVersion) == 0 {
-					outputVersion = mapping.APIVersion
-				}
-
-				obj, err = mapping.ObjectConvertor.ConvertToVersion(obj, outputVersion)
-				checkErr(err)
-			}
-
 			if err := printer.PrintObj(obj, out); err != nil {
 				checkErr(fmt.Errorf("Unable to output the provided object: %v", err))
 			}

pkg/kubectl/resource_printer.go

@@ -37,57 +37,64 @@ import (
 
 // GetPrinter returns a resource printer and a bool indicating whether the object must be
 // versioned for the given format.
-// TODO: remove the 'versioned' return value, replace with method on ResourcePrinter.
+func GetPrinter(version, format, templateFile string, defaultPrinter ResourcePrinter) (ResourcePrinter, error) {
-func GetPrinter(format, templateFile string, defaultPrinter ResourcePrinter) (ResourcePrinter, bool, error) {
-	versioned := true
 	var printer ResourcePrinter
 	switch format {
 	case "json":
-		printer = &JSONPrinter{}
+		printer = &JSONPrinter{version}
 	case "yaml":
-		printer = &YAMLPrinter{}
+		printer = &YAMLPrinter{version}
 	case "template":
 		if len(templateFile) == 0 {
-			return nil, false, fmt.Errorf("template format specified but no template given")
+			return nil, fmt.Errorf("template format specified but no template given")
 		}
 		var err error
-		printer, err = NewTemplatePrinter([]byte(templateFile))
+		printer, err = NewTemplatePrinter(version, []byte(templateFile))
 		if err != nil {
-			return nil, false, fmt.Errorf("error parsing template %s, %v\n", templateFile, err)
+			return nil, fmt.Errorf("error parsing template %s, %v\n", templateFile, err)
 		}
 	case "templatefile":
 		if len(templateFile) == 0 {
-			return nil, false, fmt.Errorf("templatefile format specified but no template file given")
+			return nil, fmt.Errorf("templatefile format specified but no template file given")
 		}
 		data, err := ioutil.ReadFile(templateFile)
 		if err != nil {
-			return nil, false, fmt.Errorf("error reading template %s, %v\n", templateFile, err)
+			return nil, fmt.Errorf("error reading template %s, %v\n", templateFile, err)
 		}
-		printer, err = NewTemplatePrinter(data)
+		printer, err = NewTemplatePrinter(version, data)
 		if err != nil {
-			return nil, false, fmt.Errorf("error parsing template %s, %v\n", string(data), err)
+			return nil, fmt.Errorf("error parsing template %s, %v\n", string(data), err)
 		}
 	case "":
 		printer = defaultPrinter
-		versioned = false
 	default:
-		return nil, false, fmt.Errorf("output format %q not recognized", format)
+		return nil, fmt.Errorf("output format %q not recognized", format)
 	}
-	return printer, versioned, nil
+	return printer, nil
 }
 
 // ResourcePrinter is an interface that knows how to print API resources.
 type ResourcePrinter interface {
 	// Print receives an arbitrary object, formats it and prints it to a writer.
 	PrintObj(runtime.Object, io.Writer) error
+
+	// Returns true if this printer emits properly versioned output.
+	IsVersioned() bool
 }
 
-// IdentityPrinter is an implementation of ResourcePrinter which simply copies the body out to the output stream.
+// JSONPrinter is an implementation of ResourcePrinter which prints as JSON.
-type JSONPrinter struct{}
+type JSONPrinter struct {
+	version string
+}
 
 // PrintObj is an implementation of ResourcePrinter.PrintObj which simply writes the object to the Writer.
-func (i *JSONPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
+func (j *JSONPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
-	data, err := latest.Codec.Encode(obj)
+	vi, err := latest.InterfacesFor(j.version)
+	if err != nil {
+		return err
+	}
+
+	data, err := vi.Codec.Encode(obj)
 	if err != nil {
 		return err
 	}
@@ -98,8 +105,16 @@ func (i *JSONPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	return err
 }
 
-func toVersionedMap(obj runtime.Object) (map[string]interface{}, error) {
+// IsVersioned returns true.
-	data, err := latest.Codec.Encode(obj)
+func (*JSONPrinter) IsVersioned() bool { return true }
+
+func toVersionedMap(version string, obj runtime.Object) (map[string]interface{}, error) {
+	vi, err := latest.InterfacesFor(version)
+	if err != nil {
+		return nil, err
+	}
+
+	data, err := vi.Codec.Encode(obj)
 	if err != nil {
 		return nil, err
 	}
@@ -111,12 +126,14 @@ func toVersionedMap(obj runtime.Object) (map[string]interface{}, error) {
 	return outObj, nil
 }
 
-// YAMLPrinter is an implementation of ResourcePrinter which parsess JSON, and re-formats as YAML.
+// YAMLPrinter is an implementation of ResourcePrinter which prints as YAML.
-type YAMLPrinter struct{}
+type YAMLPrinter struct {
+	version string
+}
 
 // PrintObj prints the data as YAML.
 func (y *YAMLPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
-	outObj, err := toVersionedMap(obj)
+	outObj, err := toVersionedMap(y.version, obj)
 	if err != nil {
 		return err
 	}
@@ -129,6 +146,9 @@ func (y *YAMLPrinter) PrintObj(obj runtime.Object, w io.Writer) error {
 	return err
 }
 
+// IsVersioned returns true.
+func (*YAMLPrinter) IsVersioned() bool { return true }
+
 type handlerEntry struct {
 	columns   []string
 	printFunc reflect.Value
@@ -140,6 +160,9 @@ type HumanReadablePrinter struct {
 	noHeaders  bool
 }
 
+// IsVersioned returns false-- human readable printers do not make versioned output.
+func (*HumanReadablePrinter) IsVersioned() bool { return false }
+
 // NewHumanReadablePrinter creates a HumanReadablePrinter.
 func NewHumanReadablePrinter(noHeaders bool) *HumanReadablePrinter {
 	printer := &HumanReadablePrinter{
@@ -337,20 +360,24 @@ func (h *HumanReadablePrinter) PrintObj(obj runtime.Object, output io.Writer) er
 
 // TemplatePrinter is an implementation of ResourcePrinter which formats data with a Go Template.
 type TemplatePrinter struct {
+	version  string
 	template *template.Template
 }
 
-func NewTemplatePrinter(tmpl []byte) (*TemplatePrinter, error) {
+func NewTemplatePrinter(version string, tmpl []byte) (*TemplatePrinter, error) {
 	t, err := template.New("output").Parse(string(tmpl))
 	if err != nil {
 		return nil, err
 	}
-	return &TemplatePrinter{t}, nil
+	return &TemplatePrinter{version, t}, nil
 }
 
+// IsVersioned returns true.
+func (*TemplatePrinter) IsVersioned() bool { return true }
+
 // PrintObj formats the obj with the Go Template.
 func (t *TemplatePrinter) PrintObj(obj runtime.Object, w io.Writer) error {
-	outObj, err := toVersionedMap(obj)
+	outObj, err := toVersionedMap(t.version, obj)
 	if err != nil {
 		return err
 	}

pkg/kubectl/resource_printer_test.go

@@ -42,9 +42,11 @@ type testStruct struct {
 
 func (ts *testStruct) IsAnAPIObject() {}
 
+const TestVersion = latest.Version
+
 func init() {
 	api.Scheme.AddKnownTypes("", &testStruct{})
-	api.Scheme.AddKnownTypes(latest.Version, &testStruct{})
+	api.Scheme.AddKnownTypes(TestVersion, &testStruct{})
 }
 
 var testData = testStruct{
@@ -55,20 +57,20 @@ var testData = testStruct{
 }
 
 func TestYAMLPrinter(t *testing.T) {
-	testPrinter(t, &YAMLPrinter{}, yaml.Unmarshal)
+	testPrinter(t, &YAMLPrinter{TestVersion}, yaml.Unmarshal)
 }
 
 func TestJSONPrinter(t *testing.T) {
-	testPrinter(t, &JSONPrinter{}, json.Unmarshal)
+	testPrinter(t, &JSONPrinter{TestVersion}, json.Unmarshal)
 }
 
 func TestPrintJSON(t *testing.T) {
 	buf := bytes.NewBuffer([]byte{})
-	printer, versioned, err := GetPrinter("json", "", nil)
+	printer, err := GetPrinter(TestVersion, "json", "", nil)
 	if err != nil {
 		t.Errorf("unexpected error: %#v", err)
 	}
-	if !versioned {
+	if !printer.IsVersioned() {
 		t.Errorf("printer should be versioned")
 	}
 	printer.PrintObj(&api.Pod{ObjectMeta: api.ObjectMeta{Name: "foo"}}, buf)
@@ -80,11 +82,11 @@ func TestPrintJSON(t *testing.T) {
 
 func TestPrintYAML(t *testing.T) {
 	buf := bytes.NewBuffer([]byte{})
-	printer, versioned, err := GetPrinter("yaml", "", nil)
+	printer, err := GetPrinter(TestVersion, "yaml", "", nil)
 	if err != nil {
 		t.Errorf("unexpected error: %#v", err)
 	}
-	if !versioned {
+	if !printer.IsVersioned() {
 		t.Errorf("printer should be versioned")
 	}
 	printer.PrintObj(&api.Pod{ObjectMeta: api.ObjectMeta{Name: "foo"}}, buf)
@@ -96,11 +98,11 @@ func TestPrintYAML(t *testing.T) {
 
 func TestPrintTemplate(t *testing.T) {
 	buf := bytes.NewBuffer([]byte{})
-	printer, versioned, err := GetPrinter("template", "{{.id}}", nil)
+	printer, err := GetPrinter(TestVersion, "template", "{{.id}}", nil)
 	if err != nil {
 		t.Fatalf("unexpected error: %#v", err)
 	}
-	if !versioned {
+	if !printer.IsVersioned() {
 		t.Errorf("printer should be versioned")
 	}
 	err = printer.PrintObj(&api.Pod{ObjectMeta: api.ObjectMeta{Name: "foo"}}, buf)
@@ -113,19 +115,19 @@ func TestPrintTemplate(t *testing.T) {
 }
 
 func TestPrintEmptyTemplate(t *testing.T) {
-	if _, _, err := GetPrinter("template", "", nil); err == nil {
+	if _, err := GetPrinter(TestVersion, "template", "", nil); err == nil {
 		t.Errorf("unexpected non-error")
 	}
 }
 
 func TestPrintBadTemplate(t *testing.T) {
-	if _, _, err := GetPrinter("template", "{{ .Name", nil); err == nil {
+	if _, err := GetPrinter(TestVersion, "template", "{{ .Name", nil); err == nil {
 		t.Errorf("unexpected non-error")
 	}
 }
 
 func TestPrintBadTemplateFile(t *testing.T) {
-	if _, _, err := GetPrinter("templatefile", "", nil); err == nil {
+	if _, err := GetPrinter(TestVersion, "templatefile", "", nil); err == nil {
 		t.Errorf("unexpected non-error")
 	}
 }
@@ -234,7 +236,7 @@ func TestUnknownTypePrinting(t *testing.T) {
 
 func TestTemplateEmitsVersionedObjects(t *testing.T) {
 	// kind is always blank in memory and set on the wire
-	printer, err := NewTemplatePrinter([]byte(`{{.kind}}`))
+	printer, err := NewTemplatePrinter(TestVersion, []byte(`{{.kind}}`))
 	if err != nil {
 		t.Fatalf("tmpl fail: %v", err)
 	}