Add a better help message for kubectl describe

When resource type isn't given in the command, print the possible
resource types. Also added the resource type description in help
strings.

pkg/kubectl/cmd/cmd.go

@@ -90,6 +90,18 @@ __custom_func() {
             ;;
     esac
 }
+`
+	valid_resources = `Valid resource types include:
+   * pods (aka 'po')
+   * replicationcontrollers (aka 'rc')
+   * services (aka 'svc')
+   * nodes (aka 'no')
+   * events (aka 'ev')
+   * secrets
+   * limits
+   * persistentVolumes (aka 'pv')
+   * persistentVolumeClaims (aka 'pvc')
+   * quota
 `
 )
 

pkg/kubectl/cmd/describe.go

@@ -23,7 +23,7 @@ import (
 
 	"github.com/spf13/cobra"
 
-	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/errors"
+	apierrors "github.com/GoogleCloudPlatform/kubernetes/pkg/api/errors"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/meta"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl"
 	cmdutil "github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl/cmd/util"
@@ -40,7 +40,12 @@ given resource or group of resources.
 $ kubectl describe RESOURCE NAME_PREFIX
 
 will first check for an exact match on RESOURCE and NAME_PREFIX. If no such resource
-exists, it will output details for every resource that has a name prefixed with NAME_PREFIX`
+exists, it will output details for every resource that has a name prefixed with NAME_PREFIX
+
+Possible resources include pods (po), replicationcontrollers (rc), services
+(svc), nodes (no), events (ev), componentstatuses (cs), limitRanges (limits),
+persistentVolumes (pv), persistentVolumeClaims (pvc), resourceQuotas (quota)
+or secrets.`
 	describe_example = `// Describe a node
 $ kubectl describe nodes kubernetes-minion-emt8.c.myproject.internal
 
@@ -78,6 +83,11 @@ func RunDescribe(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []s
 		return err
 	}
 
+	if len(args) == 0 {
+		fmt.Fprint(out, "You must specify the type of resource to describe. ", valid_resources)
+		return cmdutil.UsageError(cmd, "Required resource not specified.")
+	}
+
 	mapper, typer := f.Object()
 	r := resource.NewBuilder(mapper, typer, f.ClientMapperForCommand()).
 		ContinueOnError().
@@ -101,7 +111,7 @@ func RunDescribe(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []s
 	}
 	infos, err := r.Infos()
 	if err != nil {
-		if errors.IsNotFound(err) && len(args) == 2 {
+		if apierrors.IsNotFound(err) && len(args) == 2 {
 			return DescribeMatchingResources(mapper, typer, describer, f, cmdNamespace, args[0], args[1], out)
 		}
 		return err

pkg/kubectl/cmd/get.go

@@ -17,7 +17,6 @@ limitations under the License.
 package cmd
 
 import (
-	"errors"
 	"fmt"
 	"io"
 
@@ -101,25 +100,8 @@ func RunGet(f *cmdutil.Factory, out io.Writer, cmd *cobra.Command, args []string
 	}
 
 	if len(args) == 0 {
-		fmt.Fprint(out, `
-You must specify the type of resource to get. Valid resource types include:
-   * componentStatuses (aka 'cs')
-   * endpoints (aka 'ep')
-   * events (aka 'ev')
-   * limits
-   * namespaces
-   * nodes (aka 'no')
-   * persistentVolumeClaims (aka 'pvc')
-   * persistentVolumes (aka 'pv')
-   * pods (aka 'po')
-   * podTemplates
-   * quota
-   * replicationcontrollers (aka 'rc')
-   * secrets
-   * serviceAccounts
-   * services
-`)
-		return errors.New("Required resource not specified.")
+		fmt.Fprint(out, "You must specify the type of resource to get. ", valid_resources)
+		return cmdutil.UsageError(cmd, "Required resource not specified.")
 	}
 
 	// handle watch separately since we cannot watch multiple resource types