Merge pull request #62877 from deads2k/cli-34-describer

Automatic merge from submit-queue (batch tested with PRs 62982, 63075, 63067, 62877, 63141). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

make describers more generic from the CLI

I've made this change very small so the intent and explanation make sense to people.

Clients are not generic.  Client**Configs** are generic.  We faced this distinction in the apiserver and it took us a little to hurdle it.  When you try to provide a generic example or function, you need to provide Client**Config**, not a kube clientset.  The reason is that the code you're calling may have generated their own clientset, may want to use a dynamic one, or may want to a simple restclient.  As we seek to make `kubectl` primitives more generally applicable, this is an example we'll want to follow.  I suspect we'll be making more changes along these veins as we tease out the generic pieces of `kubectl ` to make a friendly CLI library.


@kubernetes/sig-cli-maintainers 

/hold

Holding for a few days to make sure that people have time to read and digest.

```release-note
NONE
```

pkg/kubectl/cmd/BUILD

@@ -89,7 +89,6 @@ go_library(
         "//pkg/kubectl/util/term:go_default_library",
         "//pkg/kubectl/validation:go_default_library",
         "//pkg/printers:go_default_library",
-        "//pkg/printers/internalversion:go_default_library",
         "//pkg/util/interrupt:go_default_library",
         "//pkg/util/taints:go_default_library",
         "//pkg/version:go_default_library",

pkg/kubectl/cmd/describe.go

@@ -26,13 +26,11 @@ import (
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 	"k8s.io/apimachinery/pkg/util/sets"
-	"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/resource"
 	"k8s.io/kubernetes/pkg/kubectl/util/i18n"
 	"k8s.io/kubernetes/pkg/printers"
-	printersinternal "k8s.io/kubernetes/pkg/printers/internalversion"
 )
 
 var (
@@ -75,11 +73,6 @@ func NewCmdDescribe(f cmdutil.Factory, out, cmdErr io.Writer) *cobra.Command {
 		ShowEvents: true,
 	}
 
-	// TODO: this should come from the factory, and may need to be loaded from the server, and so is probably
-	//   going to have to be removed
-	validArgs := printersinternal.DescribableResources()
-	argAliases := kubectl.ResourceAliases(validArgs)
-
 	cmd := &cobra.Command{
 		Use: "describe (-f FILENAME | TYPE [NAME_PREFIX | -l label] | TYPE/NAME)",
 		DisableFlagsInUseLine: true,
@@ -90,8 +83,6 @@ func NewCmdDescribe(f cmdutil.Factory, out, cmdErr io.Writer) *cobra.Command {
 			err := RunDescribe(f, out, cmdErr, cmd, args, options, describerSettings)
 			cmdutil.CheckErr(err)
 		},
-		ValidArgs:  validArgs,
-		ArgAliases: argAliases,
 	}
 	usage := "containing the resource to describe"
 	cmdutil.AddFilenameOptionFlags(cmd, options, usage)

pkg/kubectl/cmd/util/factory_object_mapping.go

@@ -164,16 +164,12 @@ func (f *ring1Factory) UnstructuredClientForMapping(mapping *meta.RESTMapping) (
 }
 
 func (f *ring1Factory) Describer(mapping *meta.RESTMapping) (printers.Describer, error) {
-	clientset, err := f.clientAccessFactory.ClientSet()
+	clientConfig, err := f.clientAccessFactory.ClientConfig()
-	if err != nil {
-		return nil, err
-	}
-	externalclientset, err := f.clientAccessFactory.KubernetesClientSet()
 	if err != nil {
 		return nil, err
 	}
 	// try to get a describer
-	if describer, ok := printersinternal.DescriberFor(mapping.GroupVersionKind.GroupKind(), clientset, externalclientset); ok {
+	if describer, ok := printersinternal.DescriberFor(mapping.GroupVersionKind.GroupKind(), clientConfig); ok {
 		return describer, nil
 	}
 	// if this is a kind we don't have a describer for yet, go generic if possible

pkg/printers/internalversion/BUILD

@@ -107,6 +107,7 @@ go_library(
         "//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
         "//vendor/k8s.io/client-go/dynamic:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes:go_default_library",
+        "//vendor/k8s.io/client-go/rest:go_default_library",
     ],
 )
 

pkg/printers/internalversion/describe.go

@@ -47,6 +47,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/client-go/dynamic"
 	externalclient "k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
 	"k8s.io/kubernetes/pkg/api/events"
 	"k8s.io/kubernetes/pkg/api/legacyscheme"
 	"k8s.io/kubernetes/pkg/api/ref"
@@ -123,7 +124,16 @@ func (pw *prefixWriter) Flush() {
 	}
 }
 
-func describerMap(c clientset.Interface, externalclient externalclient.Interface) map[schema.GroupKind]printers.Describer {
+func describerMap(clientConfig *rest.Config) (map[schema.GroupKind]printers.Describer, error) {
+	c, err := clientset.NewForConfig(clientConfig)
+	if err != nil {
+		return nil, err
+	}
+	externalclient, err := externalclient.NewForConfig(clientConfig)
+	if err != nil {
+		return nil, err
+	}
+
 	m := map[schema.GroupKind]printers.Describer{
 		api.Kind("Pod"):                   &PodDescriber{c},
 		api.Kind("ReplicationController"): &ReplicationControllerDescriber{c},
@@ -164,24 +174,19 @@ func describerMap(c clientset.Interface, externalclient externalclient.Interface
 		scheduling.Kind("PriorityClass"):               &PriorityClassDescriber{c},
 	}
 
-	return m
+	return m, nil
-}
-
-// DescribableResources lists all resource types we can describe.
-func DescribableResources() []string {
-	keys := make([]string, 0)
-
-	for k := range describerMap(nil, nil) {
-		resource := strings.ToLower(k.Kind)
-		keys = append(keys, resource)
-	}
-	return keys
 }
 
 // DescriberFor returns the default describe functions for each of the standard
 // Kubernetes types.
-func DescriberFor(kind schema.GroupKind, c clientset.Interface, externalclient externalclient.Interface) (printers.Describer, bool) {
+func DescriberFor(kind schema.GroupKind, clientConfig *rest.Config) (printers.Describer, bool) {
-	f, ok := describerMap(c, externalclient)[kind]
+	describers, err := describerMap(clientConfig)
+	if err != nil {
+		glog.V(1).Info(err)
+		return nil, false
+	}
+
+	f, ok := describers[kind]
 	return f, ok
 }