Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Add node debugger for k8s #46

Open
wants to merge 1 commit into
base: main
Choose a base branch
from
Open

Add node debugger for k8s #46

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 6 additions & 3 deletions cmd/exec/exec.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,10 @@ const (
cdebug exec --namespace=myns -it pod/mypod

# Start a shell in a Kubernetes pod's container:
cdebug exec -it pod/mypod/mycontainer`
cdebug exec -it pod/mypod/mycontainer

# Start a shell on a Kubernetes node:
cdebug exec -it node/mynode`
)

var (
Expand Down Expand Up @@ -123,7 +126,7 @@ func NewCommand(cli cliutil.CLI) *cobra.Command {
if sep := strings.Index(opts.target, "://"); sep != -1 {
opts.schema = opts.target[:sep+3]
opts.target = opts.target[sep+3:]
} else if strings.HasPrefix(opts.target, "pod/") || strings.HasPrefix(opts.target, "pods/") {
} else if strings.HasPrefix(opts.target, "pod/") || strings.HasPrefix(opts.target, "pods/") || strings.HasPrefix(opts.target, "node/") || strings.HasPrefix(opts.target, "nodes/") {
opts.schema = schemaKubeLong
} else {
opts.schema = schemaDocker
Expand Down Expand Up @@ -353,7 +356,7 @@ func debuggerEntrypoint(
cli,
simpleEntrypoint,
map[string]any{
"PID": targetPID,
"TARGET_PID": targetPID,
"Cmd": func() string {
if len(cmd) == 0 {
return "sh"
Expand Down
156 changes: 127 additions & 29 deletions cmd/exec/exec_kubernetes.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,51 @@ func runDebuggerKubernetes(ctx context.Context, cli cliutil.CLI, opts *options)
namespace = "default"
}

var (
podName string
debuggerName string
ephemeral bool
)
if strings.HasPrefix(opts.target, "node/") || strings.HasPrefix(opts.target, "nodes/") {
podName, debuggerName, err = runNodeDebugger(ctx, cli, opts, namespace, client)
} else {
podName, debuggerName, err = runPodDebugger(ctx, cli, opts, namespace, client)
ephemeral = true
}

if err != nil {
return fmt.Errorf("error creating debugger: %v", err)
}

if opts.detach {
attachCmd := []string{"kubectl", "attach", "-n", namespace, "-c", debuggerName}
if opts.stdin {
attachCmd = append(attachCmd, "-i")
}
if opts.tty {
attachCmd = append(attachCmd, "-t")
}
attachCmd = append(attachCmd, podName)

cli.PrintAux("Debugger container %q started in the background.\n", debuggerName)
cli.PrintAux("Use %#q if you need to attach to it.\n", strings.Join(attachCmd, " "))
return nil
}

return attachPodDebugger(
ctx,
cli,
opts,
config,
client,
namespace,
podName,
debuggerName,
ephemeral,
)
}

func runPodDebugger(ctx context.Context, cli cliutil.CLI, opts *options, namespace string, client kubernetes.Interface) (string, string, error) {
var (
podName string
targetName string
Expand All @@ -84,7 +129,7 @@ func runDebuggerKubernetes(ctx context.Context, cli cliutil.CLI, opts *options)
Pods(namespace).
Get(ctx, podName, metav1.GetOptions{})
if err != nil {
return fmt.Errorf("error getting target pod: %v", err)
return "", "", fmt.Errorf("error getting target pod: %v", err)
}

runID := uuid.ShortID()
Expand All @@ -94,7 +139,7 @@ func runDebuggerKubernetes(ctx context.Context, cli cliutil.CLI, opts *options)
cli.PrintAux("Starting debugger container...\n")

useChroot := isRootUser(opts.user) && !isReadOnlyRootFS(pod, targetName) && !runsAsNonRoot(pod, targetName)
if err := runPodDebugger(
if err := addEphemeralDebugger(
ctx,
cli,
opts,
Expand All @@ -104,37 +149,82 @@ func runDebuggerKubernetes(ctx context.Context, cli cliutil.CLI, opts *options)
debuggerName,
debuggerEntrypoint(cli, runID, 1, opts.image, opts.cmd, useChroot),
); err != nil {
return fmt.Errorf("error adding debugger container: %v", err)
return "", "", fmt.Errorf("error adding debugger container: %v", err)
}

if opts.detach {
attachCmd := []string{"kubectl", "attach", "-n", namespace, "-c", debuggerName}
if opts.stdin {
attachCmd = append(attachCmd, "-i")
}
if opts.tty {
attachCmd = append(attachCmd, "-t")
}
attachCmd = append(attachCmd, podName)
return podName, debuggerName, nil
}

cli.PrintAux("Debugger container %q started in the background.\n", debuggerName)
cli.PrintAux("Use %#q if you need to attach to it.\n", strings.Join(attachCmd, " "))
return nil
func runNodeDebugger(ctx context.Context, cli cliutil.CLI, opts *options, namespace string, client kubernetes.Interface) (string, string, error) {
opts.target = strings.TrimPrefix(opts.target, "node/")
opts.target = strings.TrimPrefix(opts.target, "nodes/")

runID := uuid.ShortID()
podName := fmt.Sprintf("cdebug-%s-%s", opts.target, runID)
debuggerName := "cdebug"
volumeName := "host-root"

p := &corev1.Pod{
ObjectMeta: metav1.ObjectMeta{
Name: podName,
Namespace: namespace,
},
Spec: corev1.PodSpec{
Containers: []corev1.Container{
{
Name: debuggerName,
Image: opts.image,
ImagePullPolicy: corev1.PullIfNotPresent,
Command: []string{"sh", "-c", debuggerEntrypoint(cli, runID, 1, opts.image, opts.cmd, false)},
Stdin: opts.stdin,
TTY: opts.tty,
// Env: TODO...
// VolumeDevices: TODO...
SecurityContext: &corev1.SecurityContext{
Privileged: &opts.privileged,
RunAsUser: uidPtr(opts.user),
RunAsGroup: gidPtr(opts.user),
},
TerminationMessagePolicy: corev1.TerminationMessageReadFile,
VolumeMounts: []corev1.VolumeMount{
{
Name: volumeName,
MountPath: "/host",
},
},
},
},
// Share host's network, PID and IPC with debug pod
HostNetwork: true,
HostPID: true,
HostIPC: true,

NodeName: opts.target,
RestartPolicy: corev1.RestartPolicyNever,
Tolerations: []corev1.Toleration{
{
Operator: corev1.TolerationOpExists,
},
},
Volumes: []corev1.Volume{
{
Name: volumeName,
VolumeSource: corev1.VolumeSource{
HostPath: &corev1.HostPathVolumeSource{Path: "/"},
},
},
},
},
}

return attachPodDebugger(
ctx,
cli,
opts,
config,
client,
namespace,
podName,
debuggerName,
)
if _, err := client.CoreV1().Pods(namespace).Create(ctx, p, metav1.CreateOptions{}); err != nil {
return "", "", fmt.Errorf("error creating debug pod: %v", err)
}

return podName, debuggerName, nil
}

func runPodDebugger(
func addEphemeralDebugger(
ctx context.Context,
cli cliutil.CLI,
opts *options,
Expand Down Expand Up @@ -316,6 +406,7 @@ func attachPodDebugger(
ns string,
podName string,
debuggerName string,
ephemeral bool,
) error {
cli.PrintAux("Waiting for debugger container...\n")
pod, err := waitForContainer(ctx, client, ns, podName, debuggerName, true)
Expand Down Expand Up @@ -343,7 +434,13 @@ func attachPodDebugger(
status.State.Terminated.ExitCode)
}

debuggerContainer := ephemeralContainerByName(pod, debuggerName)
var debuggerContainer *corev1.Container
if ephemeral {
debuggerContainer = ephemeralContainerByName(pod, debuggerName)
} else {
debuggerContainer = containerByName(pod, debuggerName)

}
if debuggerContainer == nil {
return fmt.Errorf("cannot find debugger container %q in pod %q", debuggerName, podName)
}
Expand Down Expand Up @@ -545,10 +642,11 @@ func containerByName(pod *corev1.Pod, containerName string) *corev1.Container {
return nil
}

func ephemeralContainerByName(pod *corev1.Pod, containerName string) *corev1.EphemeralContainer {
func ephemeralContainerByName(pod *corev1.Pod, containerName string) *corev1.Container {
for i := range pod.Spec.EphemeralContainers {
if pod.Spec.EphemeralContainers[i].Name == containerName {
return &pod.Spec.EphemeralContainers[i]
c := corev1.Container(pod.Spec.EphemeralContainers[i].EphemeralContainerCommon)
return &c
}
}
return nil
Expand Down