add a warning printer in cli-runtime to coordinate warning style

modified:   staging/src/k8s.io/kubectl/pkg/cmd/auth/auth.go

staging/src/k8s.io/cli-runtime/pkg/printers/warningprinter.go

@@ -0,0 +1,55 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package printers
+
+import (
+	"fmt"
+	"io"
+)
+
+const (
+	yellowColor = "\u001b[33;1m"
+	resetColor  = "\u001b[0m"
+)
+
+type WarningPrinter struct {
+	// out is the writer to output warnings to
+	out io.Writer
+	// opts contains options controlling warning output
+	opts WarningPrinterOptions
+}
+
+// WarningPrinterOptions controls the behavior of a WarningPrinter constructed using NewWarningPrinter()
+type WarningPrinterOptions struct {
+	// Color indicates that warning output can include ANSI color codes
+	Color bool
+}
+
+// NewWarningPrinter returns an implementation of warningPrinter that outputs warnings to the specified writer.
+func NewWarningPrinter(out io.Writer, opts WarningPrinterOptions) *WarningPrinter {
+	h := &WarningPrinter{out: out, opts: opts}
+	return h
+}
+
+// Print prints warnings to the configured writer.
+func (w *WarningPrinter) Print(message string) {
+	if w.opts.Color {
+		fmt.Fprintf(w.out, "%sWarning:%s %s\n", yellowColor, resetColor, message)
+	} else {
+		fmt.Fprintf(w.out, "Warning: %s\n", message)
+	}
+}

staging/src/k8s.io/kubectl/pkg/cmd/auth/cani.go

@@ -43,6 +43,7 @@ import (
 	"k8s.io/kubectl/pkg/describe"
 	rbacutil "k8s.io/kubectl/pkg/util/rbac"
 	"k8s.io/kubectl/pkg/util/templates"
+	"k8s.io/kubectl/pkg/util/term"
 )
 
 // CanIOptions is the start of the data required to perform the operation.  As new fields are added, add them here instead of
@@ -63,6 +64,7 @@ type CanIOptions struct {
 	List           bool
 
 	genericclioptions.IOStreams
+	warningPrinter *printers.WarningPrinter
 }
 
 var (
@@ -144,6 +146,8 @@ func NewCmdCanI(f cmdutil.Factory, streams genericclioptions.IOStreams) *cobra.C
 
 // Complete completes all the required options
 func (o *CanIOptions) Complete(f cmdutil.Factory, args []string) error {
+	o.warningPrinter = printers.NewWarningPrinter(o.ErrOut, printers.WarningPrinterOptions{Color: term.AllowsColorOutput(o.ErrOut)})
+
 	if o.List {
 		if len(args) != 0 {
 			return errors.New("list option must be specified with no arguments")
@@ -201,6 +205,10 @@ func (o *CanIOptions) Validate() error {
 		return nil
 	}
 
+	if o.warningPrinter == nil {
+		return fmt.Errorf("warningPrinter can not be used without initialization")
+	}
+
 	if o.NonResourceURL != "" {
 		if o.Subresource != "" {
 			return fmt.Errorf("--subresource can not be used with NonResourceURL")
@@ -209,20 +217,19 @@ func (o *CanIOptions) Validate() error {
 			return fmt.Errorf("NonResourceURL and ResourceName can not specified together")
 		}
 		if !isKnownNonResourceVerb(o.Verb) {
-			fmt.Fprintf(o.ErrOut, "Warning: verb '%s' is not a known verb\n", o.Verb)
+			o.warningPrinter.Print(fmt.Sprintf("verb '%s' is not a known verb\n", o.Verb))
 		}
 	} else if !o.Resource.Empty() && !o.AllNamespaces && o.DiscoveryClient != nil {
 		if namespaced, err := isNamespaced(o.Resource, o.DiscoveryClient); err == nil && !namespaced {
 			if len(o.Resource.Group) == 0 {
-				fmt.Fprintf(o.ErrOut, "Warning: resource '%s' is not namespace scoped\n", o.Resource.Resource)
+				o.warningPrinter.Print(fmt.Sprintf("resource '%s' is not namespace scoped\n", o.Resource.Resource))
 			} else {
-				fmt.Fprintf(o.ErrOut, "Warning: resource '%s' is not namespace scoped in group '%s'\n", o.Resource.Resource, o.Resource.Group)
+				o.warningPrinter.Print(fmt.Sprintf("resource '%s' is not namespace scoped in group '%s'\n", o.Resource.Resource, o.Resource.Group))
 			}
 		}
 		if !isKnownResourceVerb(o.Verb) {
-			fmt.Fprintf(o.ErrOut, "Warning: verb '%s' is not a known verb\n", o.Verb)
+			o.warningPrinter.Print(fmt.Sprintf("verb '%s' is not a known verb\n", o.Verb))
 		}
-
 	}
 
 	if o.NoHeaders {
@@ -309,9 +316,9 @@ func (o *CanIOptions) resourceFor(mapper meta.RESTMapper, resourceArg string) sc
 		if err != nil {
 			if !nonStandardResourceNames.Has(groupResource.String()) {
 				if len(groupResource.Group) == 0 {
-					fmt.Fprintf(o.ErrOut, "Warning: the server doesn't have a resource type '%s'\n", groupResource.Resource)
+					o.warningPrinter.Print(fmt.Sprintf("the server doesn't have a resource type '%s'\n", groupResource.Resource))
 				} else {
-					fmt.Fprintf(o.ErrOut, "Warning: the server doesn't have a resource type '%s' in group '%s'\n", groupResource.Resource, groupResource.Group)
+					o.warningPrinter.Print(fmt.Sprintf("the server doesn't have a resource type '%s' in group '%s'\n", groupResource.Resource, groupResource.Group))
 				}
 			}
 			return schema.GroupVersionResource{Resource: resourceArg}
@@ -323,7 +330,7 @@ func (o *CanIOptions) resourceFor(mapper meta.RESTMapper, resourceArg string) sc
 
 func (o *CanIOptions) printStatus(status authorizationv1.SubjectRulesReviewStatus) error {
 	if status.Incomplete {
-		fmt.Fprintf(o.ErrOut, "warning: the list may be incomplete: %v\n", status.EvaluationError)
+		o.warningPrinter.Print(fmt.Sprintf("the list may be incomplete: %v", status.EvaluationError))
 	}
 
 	breakdownRules := []rbacv1.PolicyRule{}

staging/src/k8s.io/kubectl/pkg/cmd/auth/cani_test.go

@@ -28,6 +28,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
+	"k8s.io/cli-runtime/pkg/printers"
 	restclient "k8s.io/client-go/rest"
 	"k8s.io/client-go/rest/fake"
 	cmdtesting "k8s.io/kubectl/pkg/cmd/testing"
@@ -281,7 +282,7 @@ func TestRunResourceFor(t *testing.T) {
 			expectGVR: schema.GroupVersionResource{
 				Resource: "invalid",
 			},
-			expectedErrOut: "Warning: the server doesn't have a resource type 'invalid'\n",
+			expectedErrOut: "Warning: the server doesn't have a resource type 'invalid'\n\n",
 		},
 	}
 
@@ -292,6 +293,7 @@ func TestRunResourceFor(t *testing.T) {
 
 			ioStreams, _, _, buf := genericclioptions.NewTestIOStreams()
 			test.o.IOStreams = ioStreams
+			test.o.warningPrinter = printers.NewWarningPrinter(test.o.IOStreams.ErrOut, printers.WarningPrinterOptions{Color: false})
 
 			restMapper, err := tf.ToRESTMapper()
 			if err != nil {

staging/src/k8s.io/kubectl/pkg/cmd/debug/debug.go

@@ -37,6 +37,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/strategicpatch"
 	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
+	"k8s.io/cli-runtime/pkg/printers"
 	"k8s.io/cli-runtime/pkg/resource"
 	corev1client "k8s.io/client-go/kubernetes/typed/core/v1"
 	"k8s.io/client-go/tools/cache"
@@ -50,6 +51,7 @@ import (
 	"k8s.io/kubectl/pkg/util/i18n"
 	"k8s.io/kubectl/pkg/util/interrupt"
 	"k8s.io/kubectl/pkg/util/templates"
+	"k8s.io/kubectl/pkg/util/term"
 	"k8s.io/utils/pointer"
 )
 
@@ -127,6 +129,7 @@ type DebugOptions struct {
 	podClient corev1client.CoreV1Interface
 
 	genericclioptions.IOStreams
+	warningPrinter *printers.WarningPrinter
 }
 
 // NewDebugOptions returns a DebugOptions initialized with default values.
@@ -217,6 +220,9 @@ func (o *DebugOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args []st
 	o.attachChanged = cmd.Flags().Changed("attach")
 	o.shareProcessedChanged = cmd.Flags().Changed("share-processes")
 
+	// Warning printer
+	o.warningPrinter = printers.NewWarningPrinter(o.ErrOut, printers.WarningPrinterOptions{Color: term.AllowsColorOutput(o.ErrOut)})
+
 	return nil
 }
 
@@ -293,6 +299,11 @@ func (o *DebugOptions) Validate(cmd *cobra.Command) error {
 		return fmt.Errorf("-i/--stdin is required for containers with -t/--tty=true")
 	}
 
+	// warningPrinter
+	if o.warningPrinter == nil {
+		return fmt.Errorf("warningPrinter can not be used without initialization")
+	}
+
 	return nil
 }
 
@@ -742,7 +753,7 @@ func (o *DebugOptions) waitForContainer(ctx context.Context, ns, podName, contai
 				return true, nil
 			}
 			if !o.Quiet && s.State.Waiting != nil && s.State.Waiting.Message != "" {
-				fmt.Fprintf(o.ErrOut, "Warning: container %s: %s\n", containerName, s.State.Waiting.Message)
+				o.warningPrinter.Print(fmt.Sprintf("container %s: %s", containerName, s.State.Waiting.Message))
 			}
 			return false, nil
 		})

staging/src/k8s.io/kubectl/pkg/cmd/delete/delete.go

@@ -39,6 +39,7 @@ import (
 	"k8s.io/kubectl/pkg/util/completion"
 	"k8s.io/kubectl/pkg/util/i18n"
 	"k8s.io/kubectl/pkg/util/templates"
+	"k8s.io/kubectl/pkg/util/term"
 )
 
 var (
@@ -133,6 +134,7 @@ type DeleteOptions struct {
 	Result        *resource.Result
 
 	genericclioptions.IOStreams
+	warningPrinter *printers.WarningPrinter
 }
 
 func NewCmdDelete(f cmdutil.Factory, streams genericclioptions.IOStreams) *cobra.Command {
@@ -230,6 +232,8 @@ func (o *DeleteOptions) Complete(f cmdutil.Factory, args []string, cmd *cobra.Co
 		}
 	}
 
+	o.warningPrinter = printers.NewWarningPrinter(o.ErrOut, printers.WarningPrinterOptions{Color: term.AllowsColorOutput(o.ErrOut)})
+
 	return nil
 }
 
@@ -244,10 +248,13 @@ func (o *DeleteOptions) Validate() error {
 	if o.DeleteAll && len(o.FieldSelector) > 0 {
 		return fmt.Errorf("cannot set --all and --field-selector at the same time")
 	}
+	if o.warningPrinter == nil {
+		return fmt.Errorf("warningPrinter can not be used without initialization")
+	}
 
 	switch {
 	case o.GracePeriod == 0 && o.ForceDeletion:
-		fmt.Fprintf(o.ErrOut, "warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.\n")
+		o.warningPrinter.Print("Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.")
 	case o.GracePeriod > 0 && o.ForceDeletion:
 		return fmt.Errorf("--force and --grace-period greater than 0 cannot be specified together")
 	}
@@ -311,7 +318,7 @@ func (o *DeleteOptions) DeleteResult(r *resource.Result) error {
 		options.PropagationPolicy = &o.CascadingStrategy
 
 		if warnClusterScope && info.Mapping.Scope.Name() == meta.RESTScopeNameRoot {
-			fmt.Fprintf(o.ErrOut, "warning: deleting cluster-scoped resources, not scoped to the provided namespace\n")
+			o.warningPrinter.Print("deleting cluster-scoped resources, not scoped to the provided namespace")
 			warnClusterScope = false
 		}
 

staging/src/k8s.io/kubectl/pkg/cmd/delete/delete_test.go

@@ -290,7 +290,7 @@ func TestGracePeriodScenarios(t *testing.T) {
 			forceFlag:                 true,
 			expectedGracePeriod:       "0",
 			expectedOut:               "pod/foo\n",
-			expectedErrOut:            "warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.\n",
+			expectedErrOut:            "Warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.\n",
 			expectedDeleteRequestPath: "/namespaces/test/pods/foo",
 		},
 		{
@@ -300,7 +300,7 @@ func TestGracePeriodScenarios(t *testing.T) {
 			gracePeriodFlag:           "0",
 			expectedGracePeriod:       "0",
 			expectedOut:               "pod/foo\n",
-			expectedErrOut:            "warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.\n",
+			expectedErrOut:            "Warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.\n",
 			expectedDeleteRequestPath: "/namespaces/test/pods/foo",
 		},
 		{

staging/src/k8s.io/kubectl/pkg/cmd/drain/drain.go

@@ -27,7 +27,6 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 	"k8s.io/apimachinery/pkg/util/sets"
-
 	"k8s.io/cli-runtime/pkg/genericclioptions"
 	"k8s.io/cli-runtime/pkg/printers"
 	"k8s.io/cli-runtime/pkg/resource"
@@ -37,6 +36,7 @@ import (
 	"k8s.io/kubectl/pkg/util/completion"
 	"k8s.io/kubectl/pkg/util/i18n"
 	"k8s.io/kubectl/pkg/util/templates"
+	"k8s.io/kubectl/pkg/util/term"
 )
 
 type DrainCmdOptions struct {
@@ -49,6 +49,7 @@ type DrainCmdOptions struct {
 	nodeInfos []*resource.Info
 
 	genericclioptions.IOStreams
+	warningPrinter *printers.WarningPrinter
 }
 
 var (
@@ -258,6 +259,8 @@ func (o *DrainCmdOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args [
 		return printer.PrintObj, nil
 	}
 
+	o.warningPrinter = printers.NewWarningPrinter(o.ErrOut, printers.WarningPrinterOptions{Color: term.AllowsColorOutput(o.ErrOut)})
+
 	builder := f.NewBuilder().
 		WithScheme(scheme.Scheme, scheme.Scheme.PrioritizedVersionsAllGroups()...).
 		NamespaceParam(o.Namespace).DefaultNamespace().
@@ -338,7 +341,7 @@ func (o *DrainCmdOptions) deleteOrEvictPodsSimple(nodeInfo *resource.Info) error
 		return utilerrors.NewAggregate(errs)
 	}
 	if warnings := list.Warnings(); warnings != "" {
-		fmt.Fprintf(o.ErrOut, "WARNING: %s\n", warnings)
+		o.warningPrinter.Print(warnings)
 	}
 	if o.drainer.DryRunStrategy == cmdutil.DryRunClient {
 		for _, pod := range list.Pods() {

staging/src/k8s.io/kubectl/pkg/cmd/drain/drain_test.go

@@ -599,7 +599,7 @@ func TestDrain(t *testing.T) {
 			args:                  []string{"node", "--force"},
 			expectFatal:           false,
 			expectDelete:          true,
-			expectWarning:         "WARNING: deleting Pods that declare no controller: default/bar",
+			expectWarning:         "Warning: deleting Pods that declare no controller: default/bar",
 			expectOutputToContain: "node/node drained",
 		},
 		{
@@ -620,7 +620,7 @@ func TestDrain(t *testing.T) {
 			pods:                  []corev1.Pod{dsPodWithEmptyDir},
 			rcs:                   []corev1.ReplicationController{rc},
 			args:                  []string{"node", "--ignore-daemonsets"},
-			expectWarning:         "WARNING: ignoring DaemonSet-managed Pods: default/bar",
+			expectWarning:         "Warning: ignoring DaemonSet-managed Pods: default/bar",
 			expectFatal:           false,
 			expectDelete:          false,
 			expectOutputToContain: "node/node drained",

staging/src/k8s.io/kubectl/pkg/cmd/set/set_env.go

@@ -40,6 +40,7 @@ import (
 	"k8s.io/kubectl/pkg/scheme"
 	"k8s.io/kubectl/pkg/util/i18n"
 	"k8s.io/kubectl/pkg/util/templates"
+	"k8s.io/kubectl/pkg/util/term"
 )
 
 var (
@@ -130,6 +131,7 @@ type EnvOptions struct {
 	clientset              *kubernetes.Clientset
 
 	genericclioptions.IOStreams
+	warningPrinter *printers.WarningPrinter
 }
 
 // NewEnvOptions returns an EnvOptions indicating all containers in the selected
@@ -140,14 +142,14 @@ func NewEnvOptions(streams genericclioptions.IOStreams) *EnvOptions {
 
 		ContainerSelector: "*",
 		Overwrite:         true,
-
+		IOStreams:         streams,
-		IOStreams: streams,
 	}
 }
 
 // NewCmdEnv implements the OpenShift cli env command
 func NewCmdEnv(f cmdutil.Factory, streams genericclioptions.IOStreams) *cobra.Command {
 	o := NewEnvOptions(streams)
+
 	cmd := &cobra.Command{
 		Use:                   "env RESOURCE/NAME KEY_1=VAL_1 ... KEY_N=VAL_N",
 		DisableFlagsInUseLine: true,
@@ -206,7 +208,7 @@ func contains(key string, keyList []string) bool {
 func (o *EnvOptions) keyToEnvName(key string) string {
 	envName := strings.ToUpper(validEnvNameRegexp.ReplaceAllString(key, "_"))
 	if envName != key {
-		fmt.Fprintf(o.ErrOut, "warning: key %s transferred to %s\n", key, envName)
+		o.warningPrinter.Print(fmt.Sprintf("key %s transferred to %s", key, envName))
 	}
 	return envName
 }
@@ -251,6 +253,7 @@ func (o *EnvOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args []stri
 		return err
 	}
 	o.builder = f.NewBuilder
+	o.warningPrinter = printers.NewWarningPrinter(o.ErrOut, printers.WarningPrinterOptions{Color: term.AllowsColorOutput(o.ErrOut)})
 
 	return nil
 }
@@ -269,6 +272,9 @@ func (o *EnvOptions) Validate() error {
 	if len(o.Keys) > 0 && len(o.From) == 0 {
 		return fmt.Errorf("when specifying --keys, a configmap or secret must be provided with --from")
 	}
+	if o.warningPrinter == nil {
+		return fmt.Errorf("warningPrinter can not be used without initialization")
+	}
 	return nil
 }
 
@@ -421,7 +427,7 @@ func (o *EnvOptions) RunEnv() error {
 						}
 					}
 
-					fmt.Fprintf(o.ErrOut, "warning: %s/%s does not have any containers matching %q\n", objKind, objName, o.ContainerSelector)
+					o.warningPrinter.Print(fmt.Sprintf("%s/%s does not have any containers matching %q", objKind, objName, o.ContainerSelector))
 				}
 				return nil
 			}

staging/src/k8s.io/kubectl/pkg/cmd/set/set_env_test.go

@@ -720,9 +720,9 @@ func TestSetEnvFromResource(t *testing.T) {
 			assert.NoError(t, err)
 			err = opts.RunEnv()
 			if input.warning {
-				assert.Contains(t, errOut.String(), "warning")
+				assert.Contains(t, errOut.String(), "Warning")
 			} else {
-				assert.NotContains(t, errOut.String(), "warning")
+				assert.NotContains(t, errOut.String(), "Warning")
 			}
 			assert.NoError(t, err)
 		})

test/cmd/core.sh

@@ -1481,7 +1481,7 @@ run_namespace_tests() {
   kubectl create namespace my-namespace
   kube::test::get_object_assert 'namespaces/my-namespace' "{{$id_field}}" 'my-namespace'
   output_message=$(! kubectl delete namespace -n my-namespace --all 2>&1 "${kube_flags[@]}")
-  kube::test::if_has_string "${output_message}" 'warning: deleting cluster-scoped resources'
+  kube::test::if_has_string "${output_message}" 'Warning: deleting cluster-scoped resources'
   kube::test::if_has_string "${output_message}" 'namespace "my-namespace" deleted'
 
   ### Quota

test/cmd/rbac.sh

@@ -41,7 +41,7 @@ run_clusterroles_tests() {
   kubectl create "${kube_flags[@]:?}" clusterrole pod-admin --verb=* --resource=pods
   kube::test::get_object_assert clusterrole/pod-admin "{{range.rules}}{{range.verbs}}{{.}}:{{end}}{{end}}" '\*:'
   output_message=$(kubectl delete clusterrole pod-admin -n test 2>&1 "${kube_flags[@]}")
-  kube::test::if_has_string "${output_message}" 'warning: deleting cluster-scoped resources'
+  kube::test::if_has_string "${output_message}" 'Warning: deleting cluster-scoped resources'
   kube::test::if_has_string "${output_message}" 'clusterrole.rbac.authorization.k8s.io "pod-admin" deleted'
 
   kubectl create "${kube_flags[@]}" clusterrole pod-admin --verb=* --resource=pods

test/cmd/storage.sh

@@ -46,7 +46,7 @@ run_persistent_volumes_tests() {
   kubectl create -f test/fixtures/doc-yaml/user-guide/persistent-volumes/volumes/local-01.yaml "${kube_flags[@]}"
   kube::test::get_object_assert pv "{{range.items}}{{$id_field}}:{{end}}" 'pv0001:'
   output_message=$(kubectl delete pv -n test --all 2>&1 "${kube_flags[@]}")
-  kube::test::if_has_string "${output_message}" 'warning: deleting cluster-scoped resources'
+  kube::test::if_has_string "${output_message}" 'Warning: deleting cluster-scoped resources'
   kube::test::if_has_string "${output_message}" 'persistentvolume "pv0001" deleted'
   kube::test::get_object_assert pv "{{range.items}}{{$id_field}}:{{end}}" ''