add --ignore-not-found option

pkg/kubectl/cmd/get.go

@@ -23,6 +23,7 @@ import (
 	"github.com/spf13/cobra"
 
 	"github.com/golang/glog"
+	kapierrors "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -42,7 +43,8 @@ import (
 type GetOptions struct {
 	resource.FilenameOptions
 
-	Raw string
+	IgnoreNotFound bool
+	Raw            string
 }
 
 var (
@@ -121,6 +123,7 @@ func NewCmdGet(f cmdutil.Factory, out io.Writer, errOut io.Writer) *cobra.Comman
 	cmd.Flags().Bool("watch-only", false, "Watch for changes to the requested object(s), without listing/getting first.")
 	cmd.Flags().Bool("show-kind", false, "If present, list the resource type for the requested object(s).")
 	cmd.Flags().Bool("all-namespaces", false, "If present, list the requested object(s) across all namespaces. Namespace in current context is ignored even if specified with --namespace.")
+	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.")
 	usage := "identifying the resource to get from a server."
@@ -305,6 +308,10 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 		return err
 	}
 
+	if options.IgnoreNotFound {
+		r.IgnoreErrors(kapierrors.IsNotFound)
+	}
+
 	if generic {
 		// we flattened the data from the builder, so we have individual items, but now we'd like to either:
 		// 1. if there is more than one item, combine them all into a single list
@@ -320,6 +327,10 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 			errs = append(errs, err)
 		}
 
+		if len(infos) == 0 && options.IgnoreNotFound {
+			return utilerrors.Reduce(utilerrors.Flatten(utilerrors.NewAggregate(errs)))
+		}
+
 		res := ""
 		if len(infos) > 0 {
 			res = infos[0].ResourceMapping().Resource
@@ -395,7 +406,7 @@ func RunGet(f cmdutil.Factory, out, errOut io.Writer, cmd *cobra.Command, args [
 	if err != nil {
 		allErrs = append(allErrs, err)
 	}
-	if len(infos) == 0 && len(allErrs) == 0 {
+	if len(infos) == 0 && len(allErrs) == 0 && !options.IgnoreNotFound {
 		outputEmptyListWarning(errOut)
 	}
 

pkg/kubectl/cmd/get_test.go

@@ -210,6 +210,53 @@ func TestGetObjects(t *testing.T) {
 	}
 }
 
+func TestGetObjectIgnoreNotFound(t *testing.T) {
+	initTestErrorHandler(t)
+
+	ns := &api.NamespaceList{
+		ListMeta: metav1.ListMeta{
+			ResourceVersion: "1",
+		},
+		Items: []api.Namespace{
+			{
+				ObjectMeta: metav1.ObjectMeta{Name: "testns", Namespace: "test", ResourceVersion: "11"},
+				Spec:       api.NamespaceSpec{},
+			},
+		},
+	}
+
+	f, tf, codec, _ := cmdtesting.NewAPIFactory()
+	tf.Printer = &testPrinter{}
+	tf.UnstructuredClient = &fake.RESTClient{
+		APIRegistry:          api.Registry,
+		NegotiatedSerializer: unstructuredSerializer,
+		Client: fake.CreateHTTPClient(func(req *http.Request) (*http.Response, error) {
+			switch p, m := req.URL.Path, req.Method; {
+			case p == "/namespaces/test/pods/nonexistentpod" && m == "GET":
+				return &http.Response{StatusCode: 404, Header: defaultHeader(), Body: stringBody("")}, nil
+			case p == "/api/v1/namespaces/test" && m == "GET":
+				return &http.Response{StatusCode: 200, Header: defaultHeader(), Body: objBody(codec, &ns.Items[0])}, nil
+			default:
+				t.Fatalf("unexpected request: %#v\n%#v", req.URL, req)
+				return nil, nil
+			}
+		}),
+	}
+	tf.Namespace = "test"
+	buf := bytes.NewBuffer([]byte{})
+	errBuf := bytes.NewBuffer([]byte{})
+
+	cmd := NewCmdGet(f, buf, errBuf)
+	cmd.SetOutput(buf)
+	cmd.Flags().Set("ignore-not-found", "true")
+	cmd.Flags().Set("output", "yaml")
+	cmd.Run(cmd, []string{"pods", "nonexistentpod"})
+
+	if buf.String() != "" {
+		t.Errorf("unexpected output: %s", buf.String())
+	}
+}
+
 func TestGetSortedObjects(t *testing.T) {
 	pods := &api.PodList{
 		ListMeta: metav1.ListMeta{