Get command uses print-column extn from Openapi schema

pkg/kubectl/cmd/BUILD

@@ -92,6 +92,7 @@ go_library(
         "//pkg/kubectl/cmd/templates:go_default_library",
         "//pkg/kubectl/cmd/util:go_default_library",
         "//pkg/kubectl/cmd/util/editor:go_default_library",
+        "//pkg/kubectl/cmd/util/openapi:go_default_library",
         "//pkg/kubectl/metricsutil:go_default_library",
         "//pkg/kubectl/plugins:go_default_library",
         "//pkg/kubectl/resource:go_default_library",
@@ -208,13 +209,15 @@ go_test(
         "//pkg/kubectl:go_default_library",
         "//pkg/kubectl/cmd/testing:go_default_library",
         "//pkg/kubectl/cmd/util:go_default_library",
+        "//pkg/kubectl/cmd/util/openapi:go_default_library",
         "//pkg/kubectl/plugins:go_default_library",
         "//pkg/kubectl/resource:go_default_library",
         "//pkg/printers:go_default_library",
         "//pkg/printers/internalversion:go_default_library",
         "//pkg/util/i18n:go_default_library",
         "//pkg/util/strings:go_default_library",
         "//pkg/util/term:go_default_library",
+        "//vendor/github.com/go-openapi/spec:go_default_library",
         "//vendor/github.com/spf13/cobra:go_default_library",
         "//vendor/github.com/stretchr/testify/assert:go_default_library",
         "//vendor/gopkg.in/yaml.v2:go_default_library",

pkg/kubectl/cmd/config/view.go

@@ -81,7 +81,7 @@ func NewCmdConfigView(out, errOut io.Writer, ConfigAccess clientcmd.ConfigAccess
 				cmd.Flags().Set("output", defaultOutputFormat)
 			}
 
-			printer, err := cmdutil.PrinterForCommand(cmd, meta.NewDefaultRESTMapper(nil, nil), latest.Scheme, nil, []runtime.Decoder{latest.Codec}, printers.PrintOptions{})
+			printer, err := cmdutil.PrinterForCommand(cmd, nil, meta.NewDefaultRESTMapper(nil, nil), latest.Scheme, nil, []runtime.Decoder{latest.Codec}, printers.PrintOptions{})
 			cmdutil.CheckErr(err)
 			printer = printers.NewVersionedPrinter(printer, latest.Scheme, latest.ExternalVersion)
 

pkg/kubectl/cmd/convert.go

@@ -164,7 +164,7 @@ func (o *ConvertOptions) Complete(f cmdutil.Factory, out io.Writer, cmd *cobra.C
 		cmd.Flags().Set("output", outputFormat)
 	}
 	o.encoder = f.JSONEncoder()
-	o.printer, err = f.PrinterForCommand(cmd, printers.PrintOptions{})
+	o.printer, err = f.PrinterForCommand(cmd, nil, printers.PrintOptions{})
 	if err != nil {
 		return err
 	}

pkg/kubectl/cmd/get.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"fmt"
 	"io"
+	"strings"
 
 	"github.com/golang/glog"
 	"github.com/spf13/cobra"
@@ -33,6 +34,7 @@ import (
 	"k8s.io/kubernetes/pkg/kubectl"
 	"k8s.io/kubernetes/pkg/kubectl/cmd/templates"
 	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
+	"k8s.io/kubernetes/pkg/kubectl/cmd/util/openapi"
 	"k8s.io/kubernetes/pkg/kubectl/resource"
 	"k8s.io/kubernetes/pkg/printers"
 	"k8s.io/kubernetes/pkg/util/i18n"
@@ -90,6 +92,10 @@ var (
 		kubectl get all`))
 )
 
+const (
+	useOpenAPIPrintColumnFlagLabel = "experimental-use-openapi-print-columns"
+)
+
 // NewCmdGet creates a command object for the generic "get" action, which
 // retrieves one or more resources from a server.
 func NewCmdGet(f cmdutil.Factory, out io.Writer, errOut io.Writer) *cobra.Command {
@@ -128,6 +134,7 @@ func NewCmdGet(f cmdutil.Factory, out io.Writer, errOut io.Writer) *cobra.Comman
 	cmd.Flags().BoolVar(&options.IgnoreNotFound, "ignore-not-found", false, "Treat \"resource not found\" as a successful retrieval.")
 	cmd.Flags().StringSliceP("label-columns", "L", []string{}, "Accepts a comma separated list of labels that are going to be presented as columns. Names are case-sensitive. You can also use multiple flag options like -L label1 -L label2...")
 	cmd.Flags().Bool("export", false, "If true, use 'export' for the resources.  Exported resources are stripped of cluster-specific information.")
+	addOpenAPIPrintColumnFlags(cmd)
 	usage := "identifying the resource to get from a server."
 	cmdutil.AddFilenameOptionFlags(cmd, &options.FilenameOptions, usage)
 	cmdutil.AddInclude3rdPartyFlags(cmd)
@@ -219,7 +226,7 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 		}
 		info := infos[0]
 		mapping := info.ResourceMapping()
-		printer, err := f.PrinterForMapping(cmd, mapping, allNamespaces)
+		printer, err := f.PrinterForMapping(cmd, nil, mapping, allNamespaces)
 		if err != nil {
 			return err
 		}
@@ -299,7 +306,7 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 		return err
 	}
 
-	printer, err := f.PrinterForCommand(cmd, printers.PrintOptions{})
+	printer, err := f.PrinterForCommand(cmd, nil, printers.PrintOptions{})
 	if err != nil {
 		return err
 	}
@@ -418,6 +425,8 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 	var lastMapping *meta.RESTMapping
 	w := printers.GetNewTabWriter(out)
 
+	useOpenAPIPrintColumns := cmdutil.GetFlagBool(cmd, useOpenAPIPrintColumnFlagLabel)
+
 	if resource.MultipleTypesRequested(args) || cmdutil.MustPrintWithKinds(objs, infos, sorter) {
 		showKind = true
 	}
@@ -426,6 +435,7 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 	for ix := range objs {
 		var mapping *meta.RESTMapping
 		var original runtime.Object
+
 		if sorter != nil {
 			mapping = infos[sorter.OriginalPosition(ix)].Mapping
 			original = infos[sorter.OriginalPosition(ix)].Object
@@ -437,7 +447,15 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 			if printer != nil {
 				w.Flush()
 			}
-			printer, err = f.PrinterForMapping(cmd, mapping, allNamespaces)
+
+			var outputOpts *printers.OutputOptions
+			// if cmd does not specify output format and useOpenAPIPrintColumnFlagLabel flag is true,
+			// then get the default output options for this mapping from OpenAPI schema.
+			if !cmdSpecifiesOutputFmt(cmd) && useOpenAPIPrintColumns {
+				outputOpts, _ = outputOptsForMappingFromOpenAPI(f, cmdutil.GetOpenAPICacheDir(cmd), mapping)
+			}
+
+			printer, err = f.PrinterForMapping(cmd, outputOpts, mapping, allNamespaces)
 			if err != nil {
 				if !errs.Has(err.Error()) {
 					errs.Insert(err.Error())
@@ -498,7 +516,13 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 			}
 			continue
 		}
-		if err := printer.PrintObj(decodedObj, w); err != nil {
+		objToPrint := decodedObj
+		if printer.IsGeneric() {
+			// use raw object as recieved from the builder when using generic
+			// printer instead of decodedObj
+			objToPrint = original
+		}
+		if err := printer.PrintObj(objToPrint, w); err != nil {
 			if !errs.Has(err.Error()) {
 				errs.Insert(err.Error())
 				allErrs = append(allErrs, err)
@@ -511,6 +535,59 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 	return utilerrors.NewAggregate(allErrs)
 }
 
+func addOpenAPIPrintColumnFlags(cmd *cobra.Command) {
+	cmd.Flags().Bool(useOpenAPIPrintColumnFlagLabel, false, "If true, use x-kubernetes-print-column metadata (if present) from openapi schema for displaying a resource.")
+	// marking it deprecated so that it is hidden from usage/help text.
+	cmd.Flags().MarkDeprecated(useOpenAPIPrintColumnFlagLabel, "its an experimental feature.")
+}
+
 func shouldGetNewPrinterForMapping(printer printers.ResourcePrinter, lastMapping, mapping *meta.RESTMapping) bool {
 	return printer == nil || lastMapping == nil || mapping == nil || mapping.Resource != lastMapping.Resource
 }
+
+func cmdSpecifiesOutputFmt(cmd *cobra.Command) bool {
+	return cmdutil.GetFlagString(cmd, "output") != ""
+}
+
+// outputOptsForMappingFromOpenAPI looks for the output format metatadata in the
+// openapi schema and returns the output options for the mapping if found.
+func outputOptsForMappingFromOpenAPI(f cmdutil.Factory, openAPIcacheDir string, mapping *meta.RESTMapping) (*printers.OutputOptions, bool) {
+
+	// user has not specified any output format, check if OpenAPI has
+	// default specification to print this resource type
+	api, err := f.OpenAPISchema(openAPIcacheDir)
+	if err != nil {
+		// Error getting schema
+		return nil, false
+	}
+	// Found openapi metadata for this resource
+	kind, found := api.LookupResource(mapping.GroupVersionKind)
+	if !found {
+		// Kind not found, return empty columns
+		return nil, false
+	}
+
+	columns, found := openapi.GetPrintColumns(kind.Extensions)
+	if !found {
+		// Extension not found, return empty columns
+		return nil, false
+	}
+
+	return outputOptsFromStr(columns)
+}
+
+// outputOptsFromStr parses the print-column metadata and generates printer.OutputOptions object.
+func outputOptsFromStr(columnStr string) (*printers.OutputOptions, bool) {
+	if columnStr == "" {
+		return nil, false
+	}
+	parts := strings.SplitN(columnStr, "=", 2)
+	if len(parts) < 2 {
+		return nil, false
+	}
+	return &printers.OutputOptions{
+		FmtType:          parts[0],
+		FmtArg:           parts[1],
+		AllowMissingKeys: true,
+	}, true
+}

pkg/kubectl/cmd/get_test.go

@@ -26,6 +26,8 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/go-openapi/spec"
+
 	apiequality "k8s.io/apimachinery/pkg/api/equality"
 	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -42,6 +44,7 @@ import (
 	"k8s.io/kubernetes/pkg/api/testapi"
 	apitesting "k8s.io/kubernetes/pkg/api/testing"
 	cmdtesting "k8s.io/kubernetes/pkg/kubectl/cmd/testing"
+	"k8s.io/kubernetes/pkg/kubectl/cmd/util/openapi"
 )
 
 func testData() (*api.PodList, *api.ServiceList, *api.ReplicationControllerList) {
@@ -185,6 +188,56 @@ func TestGetSchemaObject(t *testing.T) {
 	}
 }
 
+func TestGetObjectsWithOpenAPIOutputFormatPresent(t *testing.T) {
+	pods, _, _ := testData()
+
+	f, tf, codec, _ := cmdtesting.NewAPIFactory()
+	tf.Printer = &testPrinter{}
+	// overide the openAPISchema function to return custom output
+	// for Pod type.
+	tf.OpenAPISchemaFunc = testOpenAPISchemaData
+	tf.UnstructuredClient = &fake.RESTClient{
+		APIRegistry:          api.Registry,
+		NegotiatedSerializer: unstructuredSerializer,
+		Resp:                 &http.Response{StatusCode: 200, Header: defaultHeader(), Body: objBody(codec, &pods.Items[0])},
+	}
+	tf.Namespace = "test"
+	buf := bytes.NewBuffer([]byte{})
+	errBuf := bytes.NewBuffer([]byte{})
+
+	cmd := NewCmdGet(f, buf, errBuf)
+	cmd.SetOutput(buf)
+	cmd.Flags().Set(useOpenAPIPrintColumnFlagLabel, "true")
+	cmd.Run(cmd, []string{"pods", "foo"})
+
+	expected := []runtime.Object{&pods.Items[0]}
+	verifyObjects(t, expected, tf.Printer.(*testPrinter).Objects)
+
+	if len(buf.String()) == 0 {
+		t.Errorf("unexpected empty output")
+	}
+}
+
+func testOpenAPISchemaData() (*openapi.Resources, error) {
+	return &openapi.Resources{
+		GroupVersionKindToName: map[schema.GroupVersionKind]string{
+			{
+				Version: "v1",
+				Kind:    "Pod",
+			}: "io.k8s.kubernetes.pkg.api.v1.Pod",
+		},
+		NameToDefinition: map[string]openapi.Kind{
+			"io.k8s.kubernetes.pkg.api.v1.Pod": {
+				Name:       "io.k8s.kubernetes.pkg.api.v1.Pod",
+				IsResource: false,
+				Extensions: spec.Extensions{
+					"x-kubernetes-print-columns": "custom-columns=NAME:.metadata.name,RSRC:.metadata.resourceVersion",
+				},
+			},
+		},
+	}, nil
+}
+
 func TestGetObjects(t *testing.T) {
 	pods, _, _ := testData()
 

pkg/kubectl/cmd/testing/fake.go

@@ -23,7 +23,7 @@ import (
 	"path/filepath"
 	"time"
 
-	"github.com/emicklei/go-restful-swagger12"
+	swagger "github.com/emicklei/go-restful-swagger12"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 
@@ -230,6 +230,7 @@ type TestFactory struct {
 
 	ClientForMappingFunc             func(mapping *meta.RESTMapping) (resource.RESTClient, error)
 	UnstructuredClientForMappingFunc func(mapping *meta.RESTMapping) (resource.RESTClient, error)
+	OpenAPISchemaFunc                func() (*openapi.Resources, error)
 }
 
 type FakeFactory struct {
@@ -336,7 +337,7 @@ func (f *FakeFactory) Describer(*meta.RESTMapping) (printers.Describer, error) {
 	return f.tf.Describer, f.tf.Err
 }
 
-func (f *FakeFactory) PrinterForCommand(cmd *cobra.Command, options printers.PrintOptions) (printers.ResourcePrinter, error) {
+func (f *FakeFactory) PrinterForCommand(cmd *cobra.Command, outputOpts *printers.OutputOptions, options printers.PrintOptions) (printers.ResourcePrinter, error) {
 	return f.tf.Printer, f.tf.Err
 }
 
@@ -460,7 +461,7 @@ func (f *FakeFactory) PrintObject(cmd *cobra.Command, mapper meta.RESTMapper, ob
 	return nil
 }
 
-func (f *FakeFactory) PrinterForMapping(cmd *cobra.Command, mapping *meta.RESTMapping, withNamespace bool) (printers.ResourcePrinter, error) {
+func (f *FakeFactory) PrinterForMapping(cmd *cobra.Command, outputOpts *printers.OutputOptions, mapping *meta.RESTMapping, withNamespace bool) (printers.ResourcePrinter, error) {
 	return f.tf.Printer, f.tf.Err
 }
 
@@ -617,7 +618,7 @@ func (f *fakeAPIFactory) UnstructuredClientForMapping(m *meta.RESTMapping) (reso
 	return f.tf.UnstructuredClient, f.tf.Err
 }
 
-func (f *fakeAPIFactory) PrinterForCommand(cmd *cobra.Command, options printers.PrintOptions) (printers.ResourcePrinter, error) {
+func (f *fakeAPIFactory) PrinterForCommand(cmd *cobra.Command, outputOpts *printers.OutputOptions, options printers.PrintOptions) (printers.ResourcePrinter, error) {
 	return f.tf.Printer, f.tf.Err
 }
 
@@ -691,14 +692,14 @@ func (f *fakeAPIFactory) PrintObject(cmd *cobra.Command, mapper meta.RESTMapper,
 		return err
 	}
 
-	printer, err := f.PrinterForMapping(cmd, mapping, false)
+	printer, err := f.PrinterForMapping(cmd, nil, mapping, false)
 	if err != nil {
 		return err
 	}
 	return printer.PrintObj(obj, out)
 }
 
-func (f *fakeAPIFactory) PrinterForMapping(cmd *cobra.Command, mapping *meta.RESTMapping, withNamespace bool) (printers.ResourcePrinter, error) {
+func (f *fakeAPIFactory) PrinterForMapping(cmd *cobra.Command, outputOpts *printers.OutputOptions, mapping *meta.RESTMapping, withNamespace bool) (printers.ResourcePrinter, error) {
 	return f.tf.Printer, f.tf.Err
 }
 
@@ -712,6 +713,17 @@ func (f *fakeAPIFactory) SuggestedPodTemplateResources() []schema.GroupResource
 	return []schema.GroupResource{}
 }
 
+func (f *fakeAPIFactory) SwaggerSchema(schema.GroupVersionKind) (*swagger.ApiDeclaration, error) {
+	return nil, nil
+}
+
+func (f *fakeAPIFactory) OpenAPISchema(cacheDir string) (*openapi.Resources, error) {
+	if f.tf.OpenAPISchemaFunc != nil {
+		return f.tf.OpenAPISchemaFunc()
+	}
+	return &openapi.Resources{}, nil
+}
+
 func NewAPIFactory() (cmdutil.Factory, *TestFactory, runtime.Codec, runtime.NegotiatedSerializer) {
 	t := &TestFactory{
 		Validator: validation.NullSchema{},

pkg/kubectl/cmd/util/factory.go

@@ -233,10 +233,12 @@ type BuilderFactory interface {
 	// are declared on the command (see AddPrinterFlags). Returns a printer, or an error if a printer
 	// could not be found.
 	// TODO: Break the dependency on cmd here.
-	PrinterForCommand(cmd *cobra.Command, options printers.PrintOptions) (printers.ResourcePrinter, error)
+	PrinterForCommand(cmd *cobra.Command, outputOpts *printers.OutputOptions, options printers.PrintOptions) (printers.ResourcePrinter, error)
 	// PrinterForMapping returns a printer suitable for displaying the provided resource type.
 	// Requires that printer flags have been added to cmd (see AddPrinterFlags).
-	PrinterForMapping(cmd *cobra.Command, mapping *meta.RESTMapping, withNamespace bool) (printers.ResourcePrinter, error)
+	// Returns a printer, true if the printer is generic (is not internal), or
+	// an error if a printer could not be found.
+	PrinterForMapping(cmd *cobra.Command, outputOpts *printers.OutputOptions, mapping *meta.RESTMapping, withNamespace bool) (printers.ResourcePrinter, error)
 	// PrintObject prints an api object given command line flags to modify the output format
 	PrintObject(cmd *cobra.Command, mapper meta.RESTMapper, obj runtime.Object, out io.Writer) error
 	// One stop shopping for a Builder