Support custom runtime path when launching tasks

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

runtime/v2/shim_load.go

@@ -88,18 +88,35 @@ func (m *ShimManager) loadShims(ctx context.Context) error {
 			bundle.Delete()
 			continue
 		}
-		container, err := m.containers.Get(ctx, id)
-		if err != nil {
-			log.G(ctx).WithError(err).Errorf("loading container %s", id)
-			if err := mount.UnmountAll(filepath.Join(bundle.Path, "rootfs"), 0); err != nil {
-				log.G(ctx).WithError(err).Errorf("forceful unmount of rootfs %s", id)
-			}
-			bundle.Delete()
-			continue
+
+		var (
+			runtime string
+		)
+
+		// If we're on 1.6+ and specified custom path to the runtime binary, path will be saved in 'runtime' file.
+		if data, err := os.ReadFile(filepath.Join(bundle.Path, "runtime")); err == nil {
+			runtime = string(data)
+		} else if err != nil && !os.IsNotExist(err) {
+			log.G(ctx).WithError(err).Error("failed to read `runtime` path from bundle")
 		}
+
+		// Query runtime name from metadata store
+		if runtime == "" {
+			container, err := m.containers.Get(ctx, id)
+			if err != nil {
+				log.G(ctx).WithError(err).Errorf("loading container %s", id)
+				if err := mount.UnmountAll(filepath.Join(bundle.Path, "rootfs"), 0); err != nil {
+					log.G(ctx).WithError(err).Errorf("failed to unmount of rootfs %s", id)
+				}
+				bundle.Delete()
+				continue
+			}
+			runtime = container.Runtime.Name
+		}
+
 		binaryCall := shimBinary(bundle,
 			shimBinaryConfig{
-				runtime:      container.Runtime.Name,
+				runtime:      runtime,
 				address:      m.containerdAddress,
 				ttrpcAddress: m.containerdTTRPCAddress,
 				schedCore:    m.schedCore,