move Describer from factory

pkg/kubectl/cmd/util/helpers.go

@@ -37,9 +37,14 @@ import (
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/yaml"
+	"k8s.io/client-go/dynamic"
 	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
 	"k8s.io/kubernetes/pkg/kubectl"
+	"k8s.io/kubernetes/pkg/kubectl/genericclioptions"
 	"k8s.io/kubernetes/pkg/kubectl/genericclioptions/resource"
+	"k8s.io/kubernetes/pkg/printers"
+	printersinternal "k8s.io/kubernetes/pkg/printers/internalversion"
 	utilexec "k8s.io/utils/exec"
 )
 
@@ -621,3 +626,50 @@ func ShouldIncludeUninitialized(cmd *cobra.Command, includeUninitialized bool) b
 	}
 	return shouldIncludeUninitialized
 }
+
+// DescriberFunc gives a way to display the specified RESTMapping type
+type DescriberFunc func(restClientGetter genericclioptions.RESTClientGetter, mapping *meta.RESTMapping) (printers.Describer, error)
+
+// DescriberFn gives a way to easily override the function for unit testing if needed
+var DescriberFn DescriberFunc = describer
+
+// Returns a Describer for displaying the specified RESTMapping type or an error.
+func describer(restClientGetter genericclioptions.RESTClientGetter, mapping *meta.RESTMapping) (printers.Describer, error) {
+	clientConfig, err := restClientGetter.ToRESTConfig()
+	if err != nil {
+		return nil, err
+	}
+	// try to get a describer
+	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
+	if genericDescriber, genericErr := genericDescriber(restClientGetter, mapping); genericErr == nil {
+		return genericDescriber, nil
+	}
+	// otherwise return an unregistered error
+	return nil, fmt.Errorf("no description has been implemented for %s", mapping.GroupVersionKind.String())
+}
+
+// helper function to make a generic describer, or return an error
+func genericDescriber(restClientGetter genericclioptions.RESTClientGetter, mapping *meta.RESTMapping) (printers.Describer, error) {
+	clientConfig, err := restClientGetter.ToRESTConfig()
+	if err != nil {
+		return nil, err
+	}
+
+	// used to fetch the resource
+	dynamicClient, err := dynamic.NewForConfig(clientConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	// used to get events for the resource
+	clientSet, err := internalclientset.NewForConfig(clientConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	eventsClient := clientSet.Core()
+	return printersinternal.GenericDescriberFor(mapping, dynamicClient, eventsClient), nil
+}