Support to put,get and list files on k8s node

Signed-off-by: Neeraj Krishna Gopalakrishna <ngopalak@redhat.com>

Author: ngopalak-redhat

pkg/kubernetes/nodes.go

@@ -4,10 +4,21 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
 
+	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/rand"
+	"k8s.io/client-go/tools/remotecommand"
 	"k8s.io/metrics/pkg/apis/metrics"
 	metricsv1beta1api "k8s.io/metrics/pkg/apis/metrics/v1beta1"
+	"k8s.io/utils/ptr"
+
+	"github.com/containers/kubernetes-mcp-server/pkg/version"
 )
 
 func (k *Kubernetes) NodesLog(ctx context.Context, name string, query string, tailLines int64) (string, error) {
@@ -77,3 +88,247 @@ func (k *Kubernetes) NodesTop(ctx context.Context, options NodesTopOptions) (*me
 	}
 	return k.manager.accessControlClientSet.NodesMetricses(ctx, options.Name, options.ListOptions)
 }
+
+// NodeFilesOptions contains options for node file operations
+type NodeFilesOptions struct {
+	NodeName   string
+	Operation  string // "put", "get", "list"
+	SourcePath string
+	DestPath   string
+	Namespace  string
+	Image      string
+	Privileged bool
+}
+
+// NodesFiles handles file operations on a node filesystem by creating a privileged pod
+func (k *Kubernetes) NodesFiles(ctx context.Context, opts NodeFilesOptions) (string, error) {
+	// Set defaults
+	if opts.Namespace == "" {
+		opts.Namespace = "default"
+	}
+	if opts.Image == "" {
+		opts.Image = "busybox"
+	}
+
+	// Create privileged pod for accessing node filesystem
+	podName := fmt.Sprintf("node-files-%s", rand.String(5))
+	pod := &v1.Pod{
+		TypeMeta: metav1.TypeMeta{APIVersion: "v1", Kind: "Pod"},
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      podName,
+			Namespace: opts.Namespace,
+			Labels: map[string]string{
+				AppKubernetesName:      podName,
+				AppKubernetesComponent: "node-files",
+				AppKubernetesManagedBy: version.BinaryName,
+			},
+		},
+		Spec: v1.PodSpec{
+			NodeName:      opts.NodeName,
+			RestartPolicy: v1.RestartPolicyNever,
+			Containers: []v1.Container{{
+				Name:    "node-files",
+				Image:   opts.Image,
+				Command: []string{"/bin/sh", "-c", "sleep 3600"},
+				SecurityContext: &v1.SecurityContext{
+					Privileged: ptr.To(opts.Privileged),
+				},
+				VolumeMounts: []v1.VolumeMount{{
+					Name:      "node-root",
+					MountPath: "/host",
+				}},
+			}},
+			Volumes: []v1.Volume{{
+				Name: "node-root",
+				VolumeSource: v1.VolumeSource{
+					HostPath: &v1.HostPathVolumeSource{
+						Path: "/",
+					},
+				},
+			}},
+		},
+	}
+
+	// Create the pod
+	pods, err := k.manager.accessControlClientSet.Pods(opts.Namespace)
+	if err != nil {
+		return "", fmt.Errorf("failed to get pods client: %w", err)
+	}
+
+	createdPod, err := pods.Create(ctx, pod, metav1.CreateOptions{})
+	if err != nil {
+		return "", fmt.Errorf("failed to create pod: %w", err)
+	}
+
+	// Ensure pod is deleted after operation
+	defer func() {
+		deleteCtx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+		defer cancel()
+		_ = pods.Delete(deleteCtx, podName, metav1.DeleteOptions{})
+	}()
+
+	// Wait for pod to be ready
+	if err := k.waitForPodReady(ctx, opts.Namespace, podName, 2*time.Minute); err != nil {
+		return "", fmt.Errorf("pod failed to become ready: %w", err)
+	}
+
+	// Perform the requested operation
+	var result string
+	var opErr error
+	switch opts.Operation {
+	case "put":
+		result, opErr = k.nodeFilesPut(ctx, opts.Namespace, podName, opts.SourcePath, opts.DestPath)
+	case "get":
+		result, opErr = k.nodeFilesGet(ctx, opts.Namespace, podName, opts.SourcePath, opts.DestPath)
+	case "list":
+		result, opErr = k.nodeFilesList(ctx, opts.Namespace, podName, opts.SourcePath)
+	default:
+		return "", fmt.Errorf("unknown operation: %s", opts.Operation)
+	}
+
+	_ = createdPod
+	return result, opErr
+}
+
+// nodeFilesPut copies a file from local filesystem to node filesystem
+func (k *Kubernetes) nodeFilesPut(ctx context.Context, namespace, podName, sourcePath, destPath string) (string, error) {
+	// Read local file content
+	content, err := os.ReadFile(sourcePath)
+	if err != nil {
+		return "", fmt.Errorf("failed to read source file: %w", err)
+	}
+
+	// Create destination directory if needed
+	destDir := filepath.Dir(destPath)
+	if destDir != "." && destDir != "/" {
+		mkdirCmd := []string{"/bin/sh", "-c", fmt.Sprintf("mkdir -p /host%s", destDir)}
+		if _, err := k.execInPod(ctx, namespace, podName, mkdirCmd); err != nil {
+			return "", fmt.Errorf("failed to create destination directory: %w", err)
+		}
+	}
+
+	// Write content using cat command
+	escapedContent := strings.ReplaceAll(string(content), "'", "'\\''")
+	writeCmd := []string{"/bin/sh", "-c", fmt.Sprintf("cat > /host%s << 'EOF'\n%s\nEOF", destPath, escapedContent)}
+
+	if _, err := k.execInPod(ctx, namespace, podName, writeCmd); err != nil {
+		return "", fmt.Errorf("failed to write file to node: %w", err)
+	}
+
+	return fmt.Sprintf("File successfully copied from %s to node:%s", sourcePath, destPath), nil
+}
+
+// nodeFilesGet copies a file from node filesystem to local filesystem
+func (k *Kubernetes) nodeFilesGet(ctx context.Context, namespace, podName, sourcePath, destPath string) (string, error) {
+	// Read file content from node using cat
+	readCmd := []string{"/bin/sh", "-c", fmt.Sprintf("cat /host%s", sourcePath)}
+	content, err := k.execInPod(ctx, namespace, podName, readCmd)
+	if err != nil {
+		return "", fmt.Errorf("failed to read file from node: %w", err)
+	}
+
+	// Determine destination path
+	if destPath == "" {
+		destPath = filepath.Base(sourcePath)
+	}
+
+	// Create local destination directory if needed
+	destDir := filepath.Dir(destPath)
+	if destDir != "." && destDir != "" {
+		if err := os.MkdirAll(destDir, 0755); err != nil {
+			return "", fmt.Errorf("failed to create local directory: %w", err)
+		}
+	}
+
+	// Write to local file
+	if err := os.WriteFile(destPath, []byte(content), 0644); err != nil {
+		return "", fmt.Errorf("failed to write local file: %w", err)
+	}
+
+	return fmt.Sprintf("File successfully copied from node:%s to %s", sourcePath, destPath), nil
+}
+
+// nodeFilesList lists files in a directory on node filesystem
+func (k *Kubernetes) nodeFilesList(ctx context.Context, namespace, podName, path string) (string, error) {
+	// List directory contents using ls
+	listCmd := []string{"/bin/sh", "-c", fmt.Sprintf("ls -la /host%s", path)}
+	output, err := k.execInPod(ctx, namespace, podName, listCmd)
+	if err != nil {
+		return "", fmt.Errorf("failed to list directory: %w", err)
+	}
+
+	return output, nil
+}
+
+// execInPod executes a command in the pod and returns the output
+func (k *Kubernetes) execInPod(ctx context.Context, namespace, podName string, command []string) (string, error) {
+	podExecOptions := &v1.PodExecOptions{
+		Container: "node-files",
+		Command:   command,
+		Stdout:    true,
+		Stderr:    true,
+	}
+
+	executor, err := k.manager.accessControlClientSet.PodsExec(namespace, podName, podExecOptions)
+	if err != nil {
+		return "", err
+	}
+
+	stdout := &strings.Builder{}
+	stderr := &strings.Builder{}
+
+	if err = executor.StreamWithContext(ctx, remotecommand.StreamOptions{
+		Stdout: stdout,
+		Stderr: stderr,
+		Tty:    false,
+	}); err != nil {
+		if stderr.Len() > 0 {
+			return "", fmt.Errorf("exec error: %s: %w", stderr.String(), err)
+		}
+		return "", err
+	}
+
+	if stderr.Len() > 0 && stdout.Len() == 0 {
+		return stderr.String(), nil
+	}
+
+	return stdout.String(), nil
+}
+
+// waitForPodReady waits for a pod to be ready
+func (k *Kubernetes) waitForPodReady(ctx context.Context, namespace, podName string, timeout time.Duration) error {
+	pods, err := k.manager.accessControlClientSet.Pods(namespace)
+	if err != nil {
+		return err
+	}
+
+	deadline := time.Now().Add(timeout)
+	for {
+		if time.Now().After(deadline) {
+			return fmt.Errorf("timeout waiting for pod to be ready")
+		}
+
+		pod, err := pods.Get(ctx, podName, metav1.GetOptions{})
+		if err != nil {
+			return err
+		}
+
+		// Check if pod is ready
+		if pod.Status.Phase == v1.PodRunning {
+			for _, condition := range pod.Status.Conditions {
+				if condition.Type == v1.PodReady && condition.Status == v1.ConditionTrue {
+					return nil
+				}
+			}
+		}
+
+		if pod.Status.Phase == v1.PodFailed {
+			return fmt.Errorf("pod failed")
+		}
+
+		time.Sleep(2 * time.Second)
+	}
+}
+
+// Ensure io package is used (if not already imported elsewhere)
+var _ = io.Copy