fix kubectl -o

Fix kubectl -o error message:
Before this change:
```shell
kubectl get pods -o foo
error: unable to match a printer suitable for the output format "" and the options specified: &get.PrintFlags{JSONYamlPrintFlags:(*genericclioptions.JSONYamlPrintFlags)(0x23aa610), NamePrintFlags:(*genericclioptions.NamePrintFlags)(0xc42058b4e0), TemplateFlags:(*printers.KubeTemplatePrintFlags)(0xc4206765e0), CustomColumnsFlags:(*printers.CustomColumnsPrintFlags)(0xc420676620), HumanReadableFlags:(*get.HumanPrintFlags)(0xc4204eb180), NoHeaders:(*bool)(0xc4206fefbc), OutputFormat:(*string)(0xc42058b4d0)}
```

After this change:
```shell
Kubectl get pods -o foo
error: unable to match a printer suitable for the output format "aaa", allowed formats are: custom-columns,custom-columns-file,go-template,go-template-file,json,jsonpath,jsonpath-file,name,template,templatefile,wide,yaml
```

pkg/kubectl/cmd/config/flags.go

@@ -42,6 +42,13 @@ func (f *kubectlConfigPrintFlags) Complete(successTemplate string) error {
 	return f.NamePrintFlags.Complete(successTemplate)
 }
 
+func (f *kubectlConfigPrintFlags) AllowedFormats() []string {
+	formats := f.JSONYamlPrintFlags.AllowedFormats()
+	formats = append(formats, f.NamePrintFlags.AllowedFormats()...)
+	formats = append(formats, f.TemplateFlags.AllowedFormats()...)
+	return formats
+}
+
 func (f *kubectlConfigPrintFlags) ToPrinter() (printers.ResourcePrinter, error) {
 	outputFormat := ""
 	if f.OutputFormat != nil {
@@ -60,7 +67,7 @@ func (f *kubectlConfigPrintFlags) ToPrinter() (printers.ResourcePrinter, error)
 		return f.TypeSetter.WrapToPrinter(p, err)
 	}
 
-	return nil, genericclioptions.NoCompatiblePrinterError{Options: f}
+	return nil, genericclioptions.NoCompatiblePrinterError{OutputFormat: &outputFormat, AllowedFormats: f.AllowedFormats()}
 }
 
 func (f *kubectlConfigPrintFlags) AddFlags(cmd *cobra.Command) {

pkg/kubectl/cmd/create/flags.go

@@ -38,6 +38,11 @@ type PrintFlags struct {
 	OutputFormat *string
 }
 
+func (f *PrintFlags) AllowedFormats() []string {
+	return append(append(f.JSONYamlPrintFlags.AllowedFormats(), f.NamePrintFlags.AllowedFormats()...),
+		f.TemplateFlags.AllowedFormats()...)
+}
+
 func (f *PrintFlags) Complete(successTemplate string) error {
 	return f.NamePrintFlags.Complete(successTemplate)
 }
@@ -60,7 +65,7 @@ func (f *PrintFlags) ToPrinter() (printers.ResourcePrinter, error) {
 		return f.TypeSetter.WrapToPrinter(p, err)
 	}
 
-	return nil, genericclioptions.NoCompatiblePrinterError{Options: f}
+	return nil, genericclioptions.NoCompatiblePrinterError{OutputFormat: &outputFormat, AllowedFormats: f.AllowedFormats()}
 }
 
 func (f *PrintFlags) AddFlags(cmd *cobra.Command) {

pkg/kubectl/cmd/get/get_flags.go

@@ -64,6 +64,15 @@ func (f *PrintFlags) Copy() PrintFlags {
 	return printFlags
 }
 
+func (f *PrintFlags) AllowedFormats() []string {
+	formats := f.JSONYamlPrintFlags.AllowedFormats()
+	formats = append(formats, f.NamePrintFlags.AllowedFormats()...)
+	formats = append(formats, f.TemplateFlags.AllowedFormats()...)
+	formats = append(formats, f.CustomColumnsFlags.AllowedFormats()...)
+	formats = append(formats, f.HumanReadableFlags.AllowedFormats()...)
+	return formats
+}
+
 // UseOpenAPIColumns modifies the output format, as well as the
 // "allowMissingKeys" option for template printers, to values
 // defined in the OpenAPI schema of a resource.
@@ -132,7 +141,7 @@ func (f *PrintFlags) ToPrinter() (printers.ResourcePrinter, error) {
 		return p, err
 	}
 
-	return nil, genericclioptions.NoCompatiblePrinterError{Options: f}
+	return nil, genericclioptions.NoCompatiblePrinterError{OutputFormat: &outputFormat, AllowedFormats: f.AllowedFormats()}
 }
 
 // AddFlags receives a *cobra.Command reference and binds

pkg/kubectl/cmd/get/humanreadable_flags.go

@@ -61,11 +61,15 @@ func (f *HumanPrintFlags) EnsureWithNamespace() error {
 	return nil
 }
 
+func (f *HumanPrintFlags) AllowedFormats() []string {
+	return []string{"wide"}
+}
+
 // ToPrinter receives an outputFormat and returns a printer capable of
 // handling human-readable output.
 func (f *HumanPrintFlags) ToPrinter(outputFormat string) (printers.ResourcePrinter, error) {
 	if len(outputFormat) > 0 && outputFormat != "wide" {
-		return nil, genericclioptions.NoCompatiblePrinterError{Options: f}
+		return nil, genericclioptions.NoCompatiblePrinterError{Options: f, AllowedFormats: f.AllowedFormats()}
 	}
 
 	decoder := scheme.Codecs.UniversalDecoder()

pkg/kubectl/genericclioptions/json_yaml_flags.go

@@ -24,6 +24,10 @@ import (
 	"k8s.io/kubernetes/pkg/kubectl/genericclioptions/printers"
 )
 
+func (f *JSONYamlPrintFlags) AllowedFormats() []string {
+	return []string{"json", "yaml"}
+}
+
 // JSONYamlPrintFlags provides default flags necessary for json/yaml printing.
 // Given the following flag values, a printer can be requested that knows
 // how to handle printing based on these values.
@@ -44,7 +48,7 @@ func (f *JSONYamlPrintFlags) ToPrinter(outputFormat string) (printers.ResourcePr
 	case "yaml":
 		printer = &printers.YAMLPrinter{}
 	default:
-		return nil, NoCompatiblePrinterError{Options: f, OutputFormat: &outputFormat}
+		return nil, NoCompatiblePrinterError{OutputFormat: &outputFormat, AllowedFormats: f.AllowedFormats()}
 	}
 
 	return printer, nil

pkg/kubectl/genericclioptions/name_flags.go

@@ -40,6 +40,10 @@ func (f *NamePrintFlags) Complete(successTemplate string) error {
 	return nil
 }
 
+func (f *NamePrintFlags) AllowedFormats() []string {
+	return []string{"name"}
+}
+
 // ToPrinter receives an outputFormat and returns a printer capable of
 // handling --output=name printing.
 // Returns false if the specified outputFormat does not match a supported format.
@@ -57,7 +61,7 @@ func (f *NamePrintFlags) ToPrinter(outputFormat string) (printers.ResourcePrinte
 	case "":
 		return namePrinter, nil
 	default:
-		return nil, NoCompatiblePrinterError{Options: f, OutputFormat: &outputFormat}
+		return nil, NoCompatiblePrinterError{OutputFormat: &outputFormat, AllowedFormats: f.AllowedFormats()}
 	}
 }
 

pkg/kubectl/genericclioptions/print_flags.go

@@ -18,6 +18,8 @@ package genericclioptions
 
 import (
 	"fmt"
+	"sort"
+	"strings"
 
 	"github.com/spf13/cobra"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -25,8 +27,9 @@ import (
 )
 
 type NoCompatiblePrinterError struct {
-	OutputFormat *string
-	Options      interface{}
+	OutputFormat   *string
+	AllowedFormats []string
+	Options        interface{}
 }
 
 func (e NoCompatiblePrinterError) Error() string {
@@ -35,7 +38,8 @@ func (e NoCompatiblePrinterError) Error() string {
 		output = *e.OutputFormat
 	}
 
-	return fmt.Sprintf("unable to match a printer suitable for the output format %q and the options specified: %#v", output, e.Options)
+	sort.Strings(e.AllowedFormats)
+	return fmt.Sprintf("unable to match a printer suitable for the output format %q, allowed formats are: %s", output, strings.Join(e.AllowedFormats, ","))
 }
 
 func IsNoCompatiblePrinterError(err error) bool {
@@ -63,6 +67,10 @@ func (f *PrintFlags) Complete(successTemplate string) error {
 	return f.NamePrintFlags.Complete(successTemplate)
 }
 
+func (f *PrintFlags) AllowedFormats() []string {
+	return append(f.JSONYamlPrintFlags.AllowedFormats(), f.NamePrintFlags.AllowedFormats()...)
+}
+
 func (f *PrintFlags) ToPrinter() (printers.ResourcePrinter, error) {
 	outputFormat := ""
 	if f.OutputFormat != nil {
@@ -81,7 +89,7 @@ func (f *PrintFlags) ToPrinter() (printers.ResourcePrinter, error) {
 		}
 	}
 
-	return nil, NoCompatiblePrinterError{Options: f, OutputFormat: f.OutputFormat}
+	return nil, NoCompatiblePrinterError{OutputFormat: f.OutputFormat, AllowedFormats: f.AllowedFormats()}
 }
 
 func (f *PrintFlags) AddFlags(cmd *cobra.Command) {

pkg/printers/customcolumn_flags.go

@@ -27,6 +27,11 @@ import (
 	"k8s.io/kubernetes/pkg/kubectl/scheme"
 )
 
+var columnsFormats = map[string]bool{
+	"custom-columns-file": true,
+	"custom-columns":      true,
+}
+
 // CustomColumnsPrintFlags provides default flags necessary for printing
 // custom resource columns from an inline-template or file.
 type CustomColumnsPrintFlags struct {
@@ -34,6 +39,14 @@ type CustomColumnsPrintFlags struct {
 	TemplateArgument string
 }
 
+func (f *CustomColumnsPrintFlags) AllowedFormats() []string {
+	formats := make([]string, 0, len(columnsFormats))
+	for format := range columnsFormats {
+		formats = append(formats, format)
+	}
+	return formats
+}
+
 // ToPrinter receives an templateFormat and returns a printer capable of
 // handling custom-column printing.
 // Returns false if the specified templateFormat does not match a supported format.
@@ -45,13 +58,8 @@ func (f *CustomColumnsPrintFlags) ToPrinter(templateFormat string) (ResourcePrin
 
 	templateValue := ""
 
-	supportedFormats := map[string]bool{
-		"custom-columns-file": true,
-		"custom-columns":      true,
-	}
-
 	if len(f.TemplateArgument) == 0 {
-		for format := range supportedFormats {
+		for format := range columnsFormats {
 			format = format + "="
 			if strings.HasPrefix(templateFormat, format) {
 				templateValue = templateFormat[len(format):]
@@ -63,8 +71,8 @@ func (f *CustomColumnsPrintFlags) ToPrinter(templateFormat string) (ResourcePrin
 		templateValue = f.TemplateArgument
 	}
 
-	if _, supportedFormat := supportedFormats[templateFormat]; !supportedFormat {
-		return nil, genericclioptions.NoCompatiblePrinterError{}
+	if _, supportedFormat := columnsFormats[templateFormat]; !supportedFormat {
+		return nil, genericclioptions.NoCompatiblePrinterError{OutputFormat: &templateFormat, AllowedFormats: f.AllowedFormats()}
 	}
 
 	if len(templateValue) == 0 {

pkg/printers/jsonpath_flags.go

@@ -26,6 +26,14 @@ import (
 	"k8s.io/kubernetes/pkg/kubectl/genericclioptions"
 )
 
+// templates are logically optional for specifying a format.
+// this allows a user to specify a template format value
+// as --output=jsonpath=
+var jsonFormats = map[string]bool{
+	"jsonpath":      true,
+	"jsonpath-file": true,
+}
+
 // JSONPathPrintFlags provides default flags necessary for template printing.
 // Given the following flag values, a printer can be requested that knows
 // how to handle printing based on these values.
@@ -36,6 +44,14 @@ type JSONPathPrintFlags struct {
 	TemplateArgument *string
 }
 
+func (f *JSONPathPrintFlags) AllowedFormats() []string {
+	formats := make([]string, 0, len(jsonFormats))
+	for format := range jsonFormats {
+		formats = append(formats, format)
+	}
+	return formats
+}
+
 // ToPrinter receives an templateFormat and returns a printer capable of
 // handling --template format printing.
 // Returns false if the specified templateFormat does not match a template format.
@@ -46,16 +62,8 @@ func (f *JSONPathPrintFlags) ToPrinter(templateFormat string) (ResourcePrinter,
 
 	templateValue := ""
 
-	// templates are logically optional for specifying a format.
-	// this allows a user to specify a template format value
-	// as --output=jsonpath=
-	templateFormats := map[string]bool{
-		"jsonpath":      true,
-		"jsonpath-file": true,
-	}
-
 	if f.TemplateArgument == nil || len(*f.TemplateArgument) == 0 {
-		for format := range templateFormats {
+		for format := range jsonFormats {
 			format = format + "="
 			if strings.HasPrefix(templateFormat, format) {
 				templateValue = templateFormat[len(format):]
@@ -67,8 +75,8 @@ func (f *JSONPathPrintFlags) ToPrinter(templateFormat string) (ResourcePrinter,
 		templateValue = *f.TemplateArgument
 	}
 
-	if _, supportedFormat := templateFormats[templateFormat]; !supportedFormat {
-		return nil, genericclioptions.NoCompatiblePrinterError{Options: f, OutputFormat: &templateFormat}
+	if _, supportedFormat := jsonFormats[templateFormat]; !supportedFormat {
+		return nil, genericclioptions.NoCompatiblePrinterError{OutputFormat: &templateFormat, AllowedFormats: f.AllowedFormats()}
 	}
 
 	if len(templateValue) == 0 {

pkg/printers/kube_template_flags.go

@@ -33,6 +33,10 @@ type KubeTemplatePrintFlags struct {
 	TemplateArgument *string
 }
 
+func (f *KubeTemplatePrintFlags) AllowedFormats() []string {
+	return append(f.GoTemplatePrintFlags.AllowedFormats(), f.JSONPathPrintFlags.AllowedFormats()...)
+}
+
 func (f *KubeTemplatePrintFlags) ToPrinter(outputFormat string) (ResourcePrinter, error) {
 	if p, err := f.JSONPathPrintFlags.ToPrinter(outputFormat); !genericclioptions.IsNoCompatiblePrinterError(err) {
 		return p, err

pkg/printers/template_flags.go

@@ -26,6 +26,16 @@ import (
 	"k8s.io/kubernetes/pkg/kubectl/genericclioptions"
 )
 
+// templates are logically optional for specifying a format.
+// this allows a user to specify a template format value
+// as --output=go-template=
+var templateFormats = map[string]bool{
+	"template":         true,
+	"go-template":      true,
+	"go-template-file": true,
+	"templatefile":     true,
+}
+
 // GoTemplatePrintFlags provides default flags necessary for template printing.
 // Given the following flag values, a printer can be requested that knows
 // how to handle printing based on these values.
@@ -36,6 +46,14 @@ type GoTemplatePrintFlags struct {
 	TemplateArgument *string
 }
 
+func (f *GoTemplatePrintFlags) AllowedFormats() []string {
+	formats := make([]string, 0, len(templateFormats))
+	for format := range templateFormats {
+		formats = append(formats, format)
+	}
+	return formats
+}
+
 // ToPrinter receives an templateFormat and returns a printer capable of
 // handling --template format printing.
 // Returns false if the specified templateFormat does not match a template format.
@@ -46,18 +64,8 @@ func (f *GoTemplatePrintFlags) ToPrinter(templateFormat string) (ResourcePrinter
 
 	templateValue := ""
 
-	// templates are logically optional for specifying a format.
-	// this allows a user to specify a template format value
-	// as --output=go-template=
-	supportedFormats := map[string]bool{
-		"template":         true,
-		"go-template":      true,
-		"go-template-file": true,
-		"templatefile":     true,
-	}
-
 	if f.TemplateArgument == nil || len(*f.TemplateArgument) == 0 {
-		for format := range supportedFormats {
+		for format := range templateFormats {
 			format = format + "="
 			if strings.HasPrefix(templateFormat, format) {
 				templateValue = templateFormat[len(format):]
@@ -69,8 +77,8 @@ func (f *GoTemplatePrintFlags) ToPrinter(templateFormat string) (ResourcePrinter
 		templateValue = *f.TemplateArgument
 	}
 
-	if _, supportedFormat := supportedFormats[templateFormat]; !supportedFormat {
-		return nil, genericclioptions.NoCompatiblePrinterError{Options: f, OutputFormat: &templateFormat}
+	if _, supportedFormat := templateFormats[templateFormat]; !supportedFormat {
+		return nil, genericclioptions.NoCompatiblePrinterError{OutputFormat: &templateFormat, AllowedFormats: f.AllowedFormats()}
 	}
 
 	if len(templateValue) == 0 {