first commit

2025-03-01 13:03:18 +01:00
commit d89f971175
9 changed files with 775 additions and 0 deletions
@@ -0,0 +1,15 @@
+package main
+
+type Image struct {
+	Name   string
+	Pinned bool
+}
+
+// ContainerRuntime defines the interface for managing containerd images
+type ContainerRuntime interface {
+	List() ([]Image, error)
+	Pin(imageRef string) error
+	Unpin(imageRef string) error
+	Pull(imageRef string) error
+	Remove(imageRef string) error
+}
@@ -0,0 +1,183 @@
+package main
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/hex"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/containerd/containerd"
+	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/leases"
+	"github.com/containerd/containerd/namespaces"
+)
+
+// Containerd implements ContainerRuntime interface
+type Containerd struct {
+	client    *containerd.Client
+	ctx       context.Context
+	namespace string
+}
+
+// NewImageManager creates a new Containerd
+func NewImageManager(socketPath, namespace string) (*Containerd, error) {
+	client, err := containerd.New(socketPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to connect to containerd at %s: %w", socketPath, err)
+	}
+	client.LeasesService()
+
+	ctx := namespaces.WithNamespace(context.Background(), namespace)
+
+	return &Containerd{
+		client:    client,
+		ctx:       ctx,
+		namespace: namespace,
+	}, nil
+}
+
+// List returns all images with their pinned status
+func (m *Containerd) List() ([]Image, error) {
+	// Get all images
+	images, err := m.client.ImageService().List(m.ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to list images: %w", err)
+	}
+
+	// Get all leases
+	leases, err := m.client.LeasesService().List(m.ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to list leases: %w", err)
+	}
+
+	// Create a map of image references that are pinned
+	pinnedImages := make(map[string]bool)
+	for _, lease := range leases {
+		// Check if lease has labels referencing an image
+		if label, ok := lease.Labels["containerd.io/gc.ref.content.image"]; ok {
+			pinnedImages[label] = true
+		}
+	}
+
+	// Create the result list
+	var result []Image
+	for _, img := range images {
+		result = append(result, Image{
+			Name:   img.Name,
+			Pinned: pinnedImages[img.Name],
+		})
+	}
+
+	return result, nil
+}
+
+// Pin creates a lease for an image to prevent garbage collection
+func (m *Containerd) Pin(imageRef string) error {
+	// Create a unique lease ID based on image reference
+	leaseID := fmt.Sprintf("pin-%s-%d", generateID(), time.Now().UnixNano())
+
+	// Get the image to validate it exists
+	_, err := m.client.ImageService().Get(m.ctx, imageRef)
+	if err != nil {
+		return fmt.Errorf("failed to get image %s: %w", imageRef, err)
+	}
+
+	// Create a new lease
+	opts := []leases.Opt{
+		leases.WithID(leaseID),
+		leases.WithLabels(map[string]string{
+			"containerd.io/gc.ref.content.image": imageRef,
+		}),
+	}
+
+	_, err = m.client.LeasesService().Create(m.ctx, opts...)
+	if err != nil {
+		return fmt.Errorf("failed to create lease: %w", err)
+	}
+
+	return nil
+}
+
+// Unpin removes a lease for an image allowing garbage collection
+func (m *Containerd) Unpin(imageRef string) error {
+	// List all leases
+	leaseList, err := m.client.LeasesService().List(m.ctx)
+	if err != nil {
+		return fmt.Errorf("failed to list leases: %w", err)
+	}
+
+	// Find leases that reference our image
+	var foundLease bool
+	for _, lease := range leaseList {
+		// Check if this lease has a label referencing our image
+		if label, ok := lease.Labels["containerd.io/gc.ref.content.image"]; ok && label == imageRef {
+			// Delete this lease
+			if err := m.client.LeasesService().Delete(m.ctx, lease); err != nil {
+				return fmt.Errorf("failed to delete lease %s: %w", lease.ID, err)
+			}
+			foundLease = true
+		}
+	}
+
+	if !foundLease {
+		return fmt.Errorf("no lease found for image %s", imageRef)
+	}
+
+	return nil
+}
+
+// Pull pulls an image from a registry
+func (m *Containerd) Pull(imageRef string) error {
+	// Set up pull options
+	pullOpts := []containerd.RemoteOpt{
+		containerd.WithPlatform(""),
+		containerd.WithPullUnpack,
+	}
+
+	// Pull the image
+	_, err := m.client.Pull(m.ctx, imageRef, pullOpts...)
+	if err != nil {
+		return fmt.Errorf("failed to pull image %s: %w", imageRef, err)
+	}
+
+	return nil
+}
+
+// Remove deletes an image
+func (m *Containerd) Remove(imageRef string) error {
+	// Get the image
+
+	_, err := m.client.ImageService().Get(m.ctx, imageRef)
+	if err != nil {
+		if errdefs.IsNotFound(err) {
+			return fmt.Errorf("image %s not found", imageRef)
+		}
+		return fmt.Errorf("failed to get image %s: %w", imageRef, err)
+	}
+
+	// Delete the image
+	err = m.client.ImageService().Delete(m.ctx, imageRef, images.SynchronousDelete())
+	if err != nil {
+		return fmt.Errorf("failed to delete image %s: %w", imageRef, err)
+	}
+
+	return nil
+}
+
+// Close closes the containerd client connection
+func (m *Containerd) Close() error {
+	return m.client.Close()
+}
+
+// generateID creates a random unique ID
+func generateID() string {
+	b := make([]byte, 16)
+	if _, err := rand.Read(b); err != nil {
+		// Fall back to a timestamp-based ID in the unlikely event of rand failure
+		return strings.Replace(fmt.Sprintf("%d", time.Now().UnixNano()), "-", "", -1)
+	}
+	return hex.EncodeToString(b)
+}
@@ -0,0 +1,53 @@
+package main
+
+import (
+	"fmt"
+	"log"
+)
+
+func main() {
+	// Default containerd socket path
+	socketPath := "/run/containerd/containerd.sock"
+	// Default namespace for Docker with containerd
+	namespace := "moby"
+
+	// Create the image manager
+	imgManager, err := NewImageManager(socketPath, namespace)
+	if err != nil {
+		log.Fatalf("Failed to create image manager: %v", err)
+	}
+
+	img := "docker.io/library/alpine:3.20.3"
+	err = imgManager.Pull(img)
+	if err != nil {
+		panic(err)
+	}
+
+	imgs, err := imgManager.List()
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("Images: %v\n", imgs)
+
+	err = imgManager.Pin(img)
+	if err != nil {
+		panic(err)
+	}
+	imgs, err = imgManager.List()
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("Images: %v\n", imgs)
+
+	err = imgManager.Unpin(img)
+	if err != nil {
+		panic(err)
+	}
+
+	imgs, err = imgManager.List()
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("Images: %v\n", imgs)
+
+}