Add custom debug profiles on top of static profiles

This PR adds `custom` flag to let user customizes debug resources.
`custom` flag accepts partial container spec in json format.

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

@@ -20,6 +20,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"os"
 	"time"
 
 	"github.com/distribution/reference"
@@ -106,29 +107,33 @@ var (
 
 var nameSuffixFunc = utilrand.String
 
+type DebugAttachFunc func(ctx context.Context, restClientGetter genericclioptions.RESTClientGetter, cmdPath string, ns, podName, containerName string) error
+
 // DebugOptions holds the options for an invocation of kubectl debug.
 type DebugOptions struct {
-	Args            []string
-	ArgsOnly        bool
-	Attach          bool
-	AttachFunc      func(ctx context.Context, restClientGetter genericclioptions.RESTClientGetter, cmdPath string, ns, podName, containerName string) error
-	Container       string
-	CopyTo          string
-	Replace         bool
-	Env             []corev1.EnvVar
-	Image           string
-	Interactive     bool
-	Namespace       string
-	TargetNames     []string
-	PullPolicy      corev1.PullPolicy
-	Quiet           bool
-	SameNode        bool
-	SetImages       map[string]string
-	ShareProcesses  bool
-	TargetContainer string
-	TTY             bool
-	Profile         string
-	Applier         ProfileApplier
+	Args              []string
+	ArgsOnly          bool
+	Attach            bool
+	AttachFunc        DebugAttachFunc
+	Container         string
+	CopyTo            string
+	Replace           bool
+	Env               []corev1.EnvVar
+	Image             string
+	Interactive       bool
+	Namespace         string
+	TargetNames       []string
+	PullPolicy        corev1.PullPolicy
+	Quiet             bool
+	SameNode          bool
+	SetImages         map[string]string
+	ShareProcesses    bool
+	TargetContainer   string
+	TTY               bool
+	Profile           string
+	CustomProfileFile string
+	CustomProfile     *corev1.Container
+	Applier           ProfileApplier
 
 	explicitNamespace     bool
 	attachChanged         bool
@@ -193,6 +198,9 @@ func (o *DebugOptions) AddFlags(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&o.TargetContainer, "target", "", i18n.T("When using an ephemeral container, target processes in this container name."))
 	cmd.Flags().BoolVarP(&o.TTY, "tty", "t", o.TTY, i18n.T("Allocate a TTY for the debugging container."))
 	cmd.Flags().StringVar(&o.Profile, "profile", ProfileLegacy, i18n.T(`Options are "legacy", "general", "baseline", "netadmin", "restricted" or "sysadmin".`))
+	if cmdutil.DebugCustomProfile.IsEnabled() {
+		cmd.Flags().StringVar(&o.CustomProfileFile, "custom", o.CustomProfileFile, i18n.T("Path to a JSON file containing a partial container spec to customize built-in debug profiles."))
+	}
 }
 
 // Complete finishes run-time initialization of debug.DebugOptions.
@@ -256,6 +264,18 @@ func (o *DebugOptions) Complete(restClientGetter genericclioptions.RESTClientGet
 		o.Applier = applier
 	}
 
+	if o.CustomProfileFile != "" {
+		customProfileBytes, err := os.ReadFile(o.CustomProfileFile)
+		if err != nil {
+			return fmt.Errorf("must pass a container spec json file for custom profile: %w", err)
+		}
+
+		err = json.Unmarshal(customProfileBytes, &o.CustomProfile)
+		if err != nil {
+			return fmt.Errorf("%s does not contain a valid container spec: %w", o.CustomProfileFile, err)
+		}
+	}
+
 	clientConfig, err := restClientGetter.ToRESTConfig()
 	if err != nil {
 		return err
@@ -348,6 +368,12 @@ func (o *DebugOptions) Validate() error {
 		return fmt.Errorf("WarningPrinter can not be used without initialization")
 	}
 
+	if o.CustomProfile != nil {
+		if o.CustomProfile.Name != "" || len(o.CustomProfile.Command) > 0 || o.CustomProfile.Image != "" || o.CustomProfile.Lifecycle != nil || len(o.CustomProfile.VolumeDevices) > 0 {
+			return fmt.Errorf("name, command, image, lifecycle and volume devices are not modifiable via custom profile")
+		}
+	}
+
 	return nil
 }
 
@@ -467,6 +493,90 @@ func (o *DebugOptions) debugByEphemeralContainer(ctx context.Context, pod *corev
 	return result, debugContainer.Name, nil
 }
 
+// applyCustomProfile applies given partial container json file on to the profile
+// incorporated debug pod.
+func (o *DebugOptions) applyCustomProfile(debugPod *corev1.Pod, containerName string) error {
+	o.CustomProfile.Name = containerName
+	customJS, err := json.Marshal(o.CustomProfile)
+	if err != nil {
+		return fmt.Errorf("unable to marshall custom profile: %w", err)
+	}
+
+	var index int
+	found := false
+	for i, val := range debugPod.Spec.Containers {
+		if val.Name == containerName {
+			index = i
+			found = true
+			break
+		}
+	}
+
+	if !found {
+		return fmt.Errorf("unable to find the %s container in the pod %s", containerName, debugPod.Name)
+	}
+
+	var debugContainerJS []byte
+	debugContainerJS, err = json.Marshal(debugPod.Spec.Containers[index])
+	if err != nil {
+		return fmt.Errorf("unable to marshall container: %w", err)
+	}
+
+	patchedContainer, err := strategicpatch.StrategicMergePatch(debugContainerJS, customJS, corev1.Container{})
+	if err != nil {
+		return fmt.Errorf("error creating three way patch to add debug container: %w", err)
+	}
+
+	err = json.Unmarshal(patchedContainer, &debugPod.Spec.Containers[index])
+	if err != nil {
+		return fmt.Errorf("unable to unmarshall patched container to container: %w", err)
+	}
+
+	return nil
+}
+
+// applyCustomProfileEphemeral applies given partial container json file on to the profile
+// incorporated ephemeral container of the pod.
+func (o *DebugOptions) applyCustomProfileEphemeral(debugPod *corev1.Pod, containerName string) error {
+	o.CustomProfile.Name = containerName
+	customJS, err := json.Marshal(o.CustomProfile)
+	if err != nil {
+		return fmt.Errorf("unable to marshall custom profile: %w", err)
+	}
+
+	var index int
+	found := false
+	for i, val := range debugPod.Spec.EphemeralContainers {
+		if val.Name == containerName {
+			index = i
+			found = true
+			break
+		}
+	}
+
+	if !found {
+		return fmt.Errorf("unable to find the %s ephemeral container in the pod %s", containerName, debugPod.Name)
+	}
+
+	var debugContainerJS []byte
+	debugContainerJS, err = json.Marshal(debugPod.Spec.EphemeralContainers[index])
+	if err != nil {
+		return fmt.Errorf("unable to marshall ephemeral container:%w", err)
+	}
+
+	patchedContainer, err := strategicpatch.StrategicMergePatch(debugContainerJS, customJS, corev1.Container{})
+	if err != nil {
+		return fmt.Errorf("error creating three way patch to add debug container: %w", err)
+	}
+
+	err = json.Unmarshal(patchedContainer, &debugPod.Spec.EphemeralContainers[index])
+	if err != nil {
+		return fmt.Errorf("unable to unmarshall patched container to ephemeral container: %w", err)
+	}
+
+	return nil
+}
+
 // debugByCopy runs a copy of the target Pod with a debug container added or an original container modified
 func (o *DebugOptions) debugByCopy(ctx context.Context, pod *corev1.Pod) (*corev1.Pod, string, error) {
 	copied, dc, err := o.generatePodCopyWithDebugContainer(pod)
@@ -515,6 +625,13 @@ func (o *DebugOptions) generateDebugContainer(pod *corev1.Pod) (*corev1.Pod, *co
 		return nil, nil, err
 	}
 
+	if o.CustomProfile != nil {
+		err := o.applyCustomProfileEphemeral(copied, ec.Name)
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+
 	ec = &copied.Spec.EphemeralContainers[len(copied.Spec.EphemeralContainers)-1]
 
 	return copied, ec, nil
@@ -574,6 +691,13 @@ func (o *DebugOptions) generateNodeDebugPod(node *corev1.Node) (*corev1.Pod, err
 		return nil, err
 	}
 
+	if o.CustomProfile != nil {
+		err := o.applyCustomProfile(p, cn)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	return p, nil
 }
 
@@ -656,6 +780,13 @@ func (o *DebugOptions) generatePodCopyWithDebugContainer(pod *corev1.Pod) (*core
 		return nil, "", err
 	}
 
+	if o.CustomProfile != nil {
+		err = o.applyCustomProfile(copied, name)
+		if err != nil {
+			return nil, "", err
+		}
+	}
+
 	return copied, name, nil
 }
 

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

@@ -22,6 +22,8 @@ import (
 	"testing"
 	"time"
 
+	cmdutil "k8s.io/kubectl/pkg/cmd/util"
+
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
 	"github.com/spf13/cobra"
@@ -1755,6 +1757,689 @@ func TestGenerateNodeDebugPod(t *testing.T) {
 	}
 }
 
+func TestGenerateNodeDebugPodCustomProfile(t *testing.T) {
+	for _, tc := range []struct {
+		name     string
+		node     *corev1.Node
+		opts     *DebugOptions
+		expected *corev1.Pod
+	}{
+		{
+			name: "baseline profile",
+			node: &corev1.Node{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "node-XXX",
+				},
+			},
+			opts: &DebugOptions{
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileBaseline,
+				CustomProfile: &corev1.Container{
+					ImagePullPolicy: corev1.PullNever,
+					Stdin:           true,
+					TTY:             false,
+					SecurityContext: &corev1.SecurityContext{
+						Capabilities: &corev1.Capabilities{
+							Drop: []corev1.Capability{"ALL"},
+						},
+						RunAsNonRoot: pointer.Bool(false),
+					},
+				},
+			},
+			expected: &corev1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "node-debugger-node-XXX-1",
+				},
+				Spec: corev1.PodSpec{
+					Containers: []corev1.Container{
+						{
+							Name:                     "debugger",
+							Image:                    "busybox",
+							ImagePullPolicy:          corev1.PullNever,
+							TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+							VolumeMounts:             nil,
+							Stdin:                    true,
+							TTY:                      false,
+							SecurityContext: &corev1.SecurityContext{
+								RunAsNonRoot: pointer.Bool(false),
+								Capabilities: &corev1.Capabilities{
+									Drop: []corev1.Capability{"ALL"},
+								},
+							},
+						},
+					},
+					HostIPC:       false,
+					HostNetwork:   false,
+					HostPID:       false,
+					NodeName:      "node-XXX",
+					RestartPolicy: corev1.RestartPolicyNever,
+					Volumes:       nil,
+					Tolerations: []corev1.Toleration{
+						{
+							Operator: corev1.TolerationOpExists,
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "restricted profile",
+			node: &corev1.Node{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "node-XXX",
+				},
+			},
+			opts: &DebugOptions{
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileRestricted,
+				CustomProfile: &corev1.Container{
+					ImagePullPolicy: corev1.PullNever,
+					Stdin:           true,
+					TTY:             false,
+				},
+			},
+			expected: &corev1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "node-debugger-node-XXX-1",
+				},
+				Spec: corev1.PodSpec{
+					Containers: []corev1.Container{
+						{
+							Name:                     "debugger",
+							Image:                    "busybox",
+							ImagePullPolicy:          corev1.PullNever,
+							TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+							VolumeMounts:             nil,
+							Stdin:                    true,
+							TTY:                      false,
+							SecurityContext: &corev1.SecurityContext{
+								RunAsNonRoot: pointer.Bool(true),
+								Capabilities: &corev1.Capabilities{
+									Drop: []corev1.Capability{"ALL"},
+								},
+								AllowPrivilegeEscalation: pointer.Bool(false),
+								SeccompProfile:           &corev1.SeccompProfile{Type: "RuntimeDefault"},
+							},
+						},
+					},
+					HostIPC:       false,
+					HostNetwork:   false,
+					HostPID:       false,
+					NodeName:      "node-XXX",
+					RestartPolicy: corev1.RestartPolicyNever,
+					Volumes:       nil,
+					Tolerations: []corev1.Toleration{
+						{
+							Operator: corev1.TolerationOpExists,
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "netadmin profile",
+			node: &corev1.Node{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "node-XXX",
+				},
+			},
+			opts: &DebugOptions{
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileNetadmin,
+				CustomProfile: &corev1.Container{
+					Env: []corev1.EnvVar{
+						{
+							Name:  "TEST_KEY",
+							Value: "TEST_VALUE",
+						},
+					},
+				},
+			},
+			expected: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					Containers: []corev1.Container{
+						{
+							Name:                     "debugger",
+							Image:                    "busybox",
+							ImagePullPolicy:          corev1.PullIfNotPresent,
+							TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+							Env: []corev1.EnvVar{
+								{
+									Name:  "TEST_KEY",
+									Value: "TEST_VALUE",
+								},
+							},
+							VolumeMounts: nil,
+							SecurityContext: &corev1.SecurityContext{
+								Capabilities: &corev1.Capabilities{
+									Add: []corev1.Capability{"NET_ADMIN", "NET_RAW"},
+								},
+							},
+						},
+					},
+					HostIPC:       true,
+					HostNetwork:   true,
+					HostPID:       true,
+					NodeName:      "node-XXX",
+					RestartPolicy: corev1.RestartPolicyNever,
+					Volumes:       nil,
+					Tolerations: []corev1.Toleration{
+						{
+							Operator: corev1.TolerationOpExists,
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "sysadmin profile",
+			node: &corev1.Node{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "node-XXX",
+				},
+			},
+			opts: &DebugOptions{
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileSysadmin,
+				CustomProfile: &corev1.Container{
+					Env: []corev1.EnvVar{
+						{
+							Name:  "TEST_KEY",
+							Value: "TEST_VALUE",
+						},
+					},
+					VolumeMounts: []corev1.VolumeMount{
+						{
+							Name:      "host-root",
+							ReadOnly:  true,
+							MountPath: "/host",
+						},
+					},
+				},
+			},
+			expected: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					Containers: []corev1.Container{
+						{
+							Name:                     "debugger",
+							Image:                    "busybox",
+							ImagePullPolicy:          corev1.PullIfNotPresent,
+							TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+							Env: []corev1.EnvVar{
+								{
+									Name:  "TEST_KEY",
+									Value: "TEST_VALUE",
+								},
+							},
+							VolumeMounts: []corev1.VolumeMount{
+								{
+									Name:      "host-root",
+									ReadOnly:  true,
+									MountPath: "/host",
+								},
+							},
+							SecurityContext: &corev1.SecurityContext{
+								Privileged: pointer.Bool(true),
+							},
+						},
+					},
+					HostIPC:       true,
+					HostNetwork:   true,
+					HostPID:       true,
+					NodeName:      "node-XXX",
+					RestartPolicy: corev1.RestartPolicyNever,
+					Volumes: []corev1.Volume{
+						{
+							Name: "host-root",
+							VolumeSource: corev1.VolumeSource{
+								HostPath: &corev1.HostPathVolumeSource{
+									Path: "/",
+								},
+							},
+						},
+					},
+					Tolerations: []corev1.Toleration{
+						{
+							Operator: corev1.TolerationOpExists,
+						},
+					},
+				},
+			},
+		},
+	} {
+
+		t.Run(tc.name, func(t *testing.T) {
+			cmdtesting.WithAlphaEnvs([]cmdutil.FeatureGate{cmdutil.DebugCustomProfile}, t, func(t *testing.T) {
+				var err error
+				tc.opts.Applier, err = NewProfileApplier(tc.opts.Profile)
+				if err != nil {
+					t.Fatalf("Fail to create profile applier: %s: %v", tc.opts.Profile, err)
+				}
+				tc.opts.IOStreams = genericiooptions.NewTestIOStreamsDiscard()
+
+				pod, err := tc.opts.generateNodeDebugPod(tc.node)
+				if err != nil {
+					t.Fatalf("Fail to generate node debug pod: %v", err)
+				}
+				tc.expected.Name = pod.Name
+				if diff := cmp.Diff(tc.expected, pod); diff != "" {
+					t.Error("unexpected diff in generated object: (-want +got):\n", diff)
+				}
+			})
+		})
+	}
+}
+
+func TestGenerateCopyDebugPodCustomProfile(t *testing.T) {
+	for _, tc := range []struct {
+		name     string
+		copyPod  *corev1.Pod
+		opts     *DebugOptions
+		expected *corev1.Pod
+	}{
+		{
+			name: "baseline profile",
+			copyPod: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+				},
+			},
+			opts: &DebugOptions{
+				SameNode:   true,
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileBaseline,
+				CustomProfile: &corev1.Container{
+					ImagePullPolicy: corev1.PullNever,
+					Stdin:           true,
+					TTY:             false,
+					SecurityContext: &corev1.SecurityContext{
+						Capabilities: &corev1.Capabilities{
+							Drop: []corev1.Capability{"ALL"},
+						},
+						RunAsNonRoot: pointer.Bool(false),
+					},
+				},
+			},
+			expected: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+					Containers: []corev1.Container{
+						{
+							Image:                    "busybox",
+							ImagePullPolicy:          corev1.PullNever,
+							TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+							VolumeMounts:             nil,
+							Stdin:                    true,
+							TTY:                      false,
+							SecurityContext: &corev1.SecurityContext{
+								RunAsNonRoot: pointer.Bool(false),
+								Capabilities: &corev1.Capabilities{
+									Drop: []corev1.Capability{"ALL"},
+								},
+							},
+						},
+					},
+					HostIPC:               false,
+					HostNetwork:           false,
+					HostPID:               false,
+					Volumes:               nil,
+					ShareProcessNamespace: pointer.Bool(true),
+				},
+			},
+		},
+		{
+			name: "restricted profile",
+			copyPod: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+				},
+			},
+			opts: &DebugOptions{
+				SameNode:   true,
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileRestricted,
+				CustomProfile: &corev1.Container{
+					ImagePullPolicy: corev1.PullNever,
+					Stdin:           true,
+					TTY:             false,
+					SecurityContext: &corev1.SecurityContext{
+						Capabilities: &corev1.Capabilities{
+							Drop: []corev1.Capability{"ALL"},
+						},
+						RunAsNonRoot: pointer.Bool(false),
+					},
+				},
+			},
+			expected: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+					Containers: []corev1.Container{
+						{
+							Image:                    "busybox",
+							ImagePullPolicy:          corev1.PullNever,
+							TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+							VolumeMounts:             nil,
+							Stdin:                    true,
+							TTY:                      false,
+							SecurityContext: &corev1.SecurityContext{
+								AllowPrivilegeEscalation: pointer.Bool(false),
+								RunAsNonRoot:             pointer.Bool(false),
+								Capabilities: &corev1.Capabilities{
+									Drop: []corev1.Capability{"ALL"},
+								},
+								SeccompProfile: &corev1.SeccompProfile{
+									Type:             corev1.SeccompProfileTypeRuntimeDefault,
+									LocalhostProfile: nil,
+								},
+							},
+						},
+					},
+					HostIPC:               false,
+					HostNetwork:           false,
+					HostPID:               false,
+					Volumes:               nil,
+					ShareProcessNamespace: pointer.Bool(true),
+				},
+			},
+		},
+		{
+			name: "sysadmin profile",
+			copyPod: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+				},
+			},
+			opts: &DebugOptions{
+				SameNode:   true,
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileRestricted,
+				CustomProfile: &corev1.Container{
+					ImagePullPolicy: corev1.PullNever,
+					Stdin:           true,
+					TTY:             false,
+					SecurityContext: &corev1.SecurityContext{
+						Capabilities: &corev1.Capabilities{
+							Drop: []corev1.Capability{"ALL"},
+						},
+						RunAsNonRoot: pointer.Bool(false),
+					},
+				},
+			},
+			expected: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+					Containers: []corev1.Container{
+						{
+							Image:                    "busybox",
+							ImagePullPolicy:          corev1.PullNever,
+							TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+							VolumeMounts:             nil,
+							Stdin:                    true,
+							TTY:                      false,
+							SecurityContext: &corev1.SecurityContext{
+								AllowPrivilegeEscalation: pointer.Bool(false),
+								RunAsNonRoot:             pointer.Bool(false),
+								Capabilities: &corev1.Capabilities{
+									Drop: []corev1.Capability{"ALL"},
+								},
+								SeccompProfile: &corev1.SeccompProfile{
+									Type:             corev1.SeccompProfileTypeRuntimeDefault,
+									LocalhostProfile: nil,
+								},
+							},
+						},
+					},
+					HostIPC:               false,
+					HostNetwork:           false,
+					HostPID:               false,
+					Volumes:               nil,
+					ShareProcessNamespace: pointer.Bool(true),
+				},
+			},
+		},
+	} {
+
+		t.Run(tc.name, func(t *testing.T) {
+			cmdtesting.WithAlphaEnvs([]cmdutil.FeatureGate{cmdutil.DebugCustomProfile}, t, func(t *testing.T) {
+				var err error
+				tc.opts.Applier, err = NewProfileApplier(tc.opts.Profile)
+				if err != nil {
+					t.Fatalf("Fail to create profile applier: %s: %v", tc.opts.Profile, err)
+				}
+				tc.opts.IOStreams = genericiooptions.NewTestIOStreamsDiscard()
+
+				pod, dc, err := tc.opts.generatePodCopyWithDebugContainer(tc.copyPod)
+				if err != nil {
+					t.Fatalf("Fail to generate node debug pod: %v", err)
+				}
+				tc.expected.Spec.Containers[0].Name = dc
+				if diff := cmp.Diff(tc.expected, pod); diff != "" {
+					t.Error("unexpected diff in generated object: (-want +got):\n", diff)
+				}
+			})
+		})
+	}
+}
+
+func TestGenerateEphemeralDebugPodCustomProfile(t *testing.T) {
+	for _, tc := range []struct {
+		name     string
+		copyPod  *corev1.Pod
+		opts     *DebugOptions
+		expected *corev1.Pod
+	}{
+		{
+			name: "baseline profile",
+			copyPod: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+				},
+			},
+			opts: &DebugOptions{
+				SameNode:   true,
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileBaseline,
+				CustomProfile: &corev1.Container{
+					ImagePullPolicy: corev1.PullNever,
+					Stdin:           true,
+					TTY:             false,
+					SecurityContext: &corev1.SecurityContext{
+						Capabilities: &corev1.Capabilities{
+							Drop: []corev1.Capability{"ALL"},
+						},
+						RunAsNonRoot: pointer.Bool(false),
+					},
+				},
+			},
+			expected: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+					EphemeralContainers: []corev1.EphemeralContainer{
+						{
+							EphemeralContainerCommon: corev1.EphemeralContainerCommon{
+								Name:                     "debugger-1",
+								Image:                    "busybox",
+								ImagePullPolicy:          corev1.PullNever,
+								TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+								VolumeMounts:             nil,
+								Stdin:                    true,
+								TTY:                      false,
+								SecurityContext: &corev1.SecurityContext{
+									RunAsNonRoot: pointer.Bool(false),
+									Capabilities: &corev1.Capabilities{
+										Drop: []corev1.Capability{"ALL"},
+									},
+								},
+							},
+						},
+					},
+					HostIPC:     false,
+					HostNetwork: false,
+					HostPID:     false,
+					Volumes:     nil,
+				},
+			},
+		},
+		{
+			name: "restricted profile",
+			copyPod: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+				},
+			},
+			opts: &DebugOptions{
+				SameNode:   true,
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileRestricted,
+				CustomProfile: &corev1.Container{
+					ImagePullPolicy: corev1.PullNever,
+					Stdin:           true,
+					TTY:             false,
+					SecurityContext: &corev1.SecurityContext{
+						Capabilities: &corev1.Capabilities{
+							Drop: []corev1.Capability{"ALL"},
+						},
+						RunAsNonRoot: pointer.Bool(false),
+					},
+				},
+			},
+			expected: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+					EphemeralContainers: []corev1.EphemeralContainer{
+						{
+							EphemeralContainerCommon: corev1.EphemeralContainerCommon{
+								Name:                     "debugger-1",
+								Image:                    "busybox",
+								ImagePullPolicy:          corev1.PullNever,
+								TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+								VolumeMounts:             nil,
+								Stdin:                    true,
+								TTY:                      false,
+								SecurityContext: &corev1.SecurityContext{
+									AllowPrivilegeEscalation: pointer.Bool(false),
+									RunAsNonRoot:             pointer.Bool(false),
+									Capabilities: &corev1.Capabilities{
+										Drop: []corev1.Capability{"ALL"},
+									},
+									SeccompProfile: &corev1.SeccompProfile{
+										Type:             corev1.SeccompProfileTypeRuntimeDefault,
+										LocalhostProfile: nil,
+									},
+								},
+							},
+						},
+					},
+					HostIPC:     false,
+					HostNetwork: false,
+					HostPID:     false,
+					Volumes:     nil,
+				},
+			},
+		},
+		{
+			name: "sysadmin profile",
+			copyPod: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+				},
+			},
+			opts: &DebugOptions{
+				SameNode:   true,
+				Image:      "busybox",
+				PullPolicy: corev1.PullIfNotPresent,
+				Profile:    ProfileRestricted,
+				CustomProfile: &corev1.Container{
+					ImagePullPolicy: corev1.PullNever,
+					Stdin:           true,
+					TTY:             false,
+					SecurityContext: &corev1.SecurityContext{
+						Capabilities: &corev1.Capabilities{
+							Drop: []corev1.Capability{"ALL"},
+						},
+						RunAsNonRoot: pointer.Bool(false),
+					},
+				},
+			},
+			expected: &corev1.Pod{
+				Spec: corev1.PodSpec{
+					ServiceAccountName: "test",
+					NodeName:           "test-node",
+					EphemeralContainers: []corev1.EphemeralContainer{
+						{
+							EphemeralContainerCommon: corev1.EphemeralContainerCommon{
+								Name:                     "debugger-1",
+								Image:                    "busybox",
+								ImagePullPolicy:          corev1.PullNever,
+								TerminationMessagePolicy: corev1.TerminationMessageReadFile,
+								VolumeMounts:             nil,
+								Stdin:                    true,
+								TTY:                      false,
+								SecurityContext: &corev1.SecurityContext{
+									AllowPrivilegeEscalation: pointer.Bool(false),
+									RunAsNonRoot:             pointer.Bool(false),
+									Capabilities: &corev1.Capabilities{
+										Drop: []corev1.Capability{"ALL"},
+									},
+									SeccompProfile: &corev1.SeccompProfile{
+										Type:             corev1.SeccompProfileTypeRuntimeDefault,
+										LocalhostProfile: nil,
+									},
+								},
+							},
+						},
+					},
+					HostIPC:     false,
+					HostNetwork: false,
+					HostPID:     false,
+					Volumes:     nil,
+				},
+			},
+		},
+	} {
+
+		t.Run(tc.name, func(t *testing.T) {
+			cmdtesting.WithAlphaEnvs([]cmdutil.FeatureGate{cmdutil.DebugCustomProfile}, t, func(t *testing.T) {
+				var err error
+				tc.opts.Applier, err = NewProfileApplier(tc.opts.Profile)
+				if err != nil {
+					t.Fatalf("Fail to create profile applier: %s: %v", tc.opts.Profile, err)
+				}
+				tc.opts.IOStreams = genericiooptions.NewTestIOStreamsDiscard()
+
+				pod, ec, err := tc.opts.generateDebugContainer(tc.copyPod)
+				if err != nil {
+					t.Fatalf("Fail to generate node debug pod: %v", err)
+				}
+				tc.expected.Spec.EphemeralContainers[0].Name = ec.Name
+				if diff := cmp.Diff(tc.expected, pod); diff != "" {
+					t.Error("unexpected diff in generated object: (-want +got):\n", diff)
+				}
+			})
+		})
+	}
+}
+
 func TestCompleteAndValidate(t *testing.T) {
 	tf := cmdtesting.NewTestFactory().WithNamespace("test")
 	ioStreams, _, _, _ := genericiooptions.NewTestIOStreams()

staging/src/k8s.io/kubectl/pkg/cmd/util/helpers.go

@@ -431,6 +431,7 @@ const (
 	OpenAPIV3Patch          FeatureGate = "KUBECTL_OPENAPIV3_PATCH"
 	RemoteCommandWebsockets FeatureGate = "KUBECTL_REMOTE_COMMAND_WEBSOCKETS"
 	PortForwardWebsockets   FeatureGate = "KUBECTL_PORT_FORWARD_WEBSOCKETS"
+	DebugCustomProfile      FeatureGate = "KUBECTL_DEBUG_CUSTOM_PROFILE"
 )
 
 // IsEnabled returns true iff environment variable is set to true.