// overlayRender renders the image that corresponds to the given hash using the
// overlay filesystem. It mounts an overlay filesystem from the cached tree of
// the image as rootfs.
func overlayRender(cfg RunConfig, treeStoreID string, cdir string, dest string, appName string) error {
cachedTreePath := cfg.TreeStore.GetRootFS(treeStoreID)
mc, err := prepareOverlay(cachedTreePath, treeStoreID, cdir, dest, appName, cfg.MountLabel,
cfg.RktGid, common.DefaultRegularDirPerm)
if err != nil {
return errwrap.Wrap(errors.New("problem preparing overlay directories"), err)
}
if err = overlay.Mount(mc); err != nil {
return errwrap.Wrap(errors.New("problem mounting overlay filesystem"), err)
}
return nil
}
// mountOverlay mounts the app from the overlay-rendered pod to the destination directory.
func mountOverlay(pod *pod, app *schema.RuntimeApp, dest string) error {
if _, err := os.Stat(dest); err != nil {
return err
}
s, err := imagestore.NewStore(getDataDir())
if err != nil {
return errwrap.Wrap(errors.New("cannot open store"), err)
}
ts, err := treestore.NewStore(treeStoreDir(), s)
if err != nil {
return errwrap.Wrap(errors.New("cannot open treestore"), err)
}
treeStoreID, err := pod.getAppTreeStoreID(app.Name)
if err != nil {
return err
}
lower := ts.GetRootFS(treeStoreID)
imgDir := filepath.Join(filepath.Join(pod.path(), "overlay"), treeStoreID)
if _, err := os.Stat(imgDir); err != nil {
return err
}
upper := filepath.Join(imgDir, "upper", app.Name.String())
if _, err := os.Stat(upper); err != nil {
return err
}
work := filepath.Join(imgDir, "work", app.Name.String())
if _, err := os.Stat(work); err != nil {
return err
}
if err := overlay.Mount(&overlay.MountCfg{lower, upper, work, dest, ""}); err != nil {
return errwrap.Wrap(errors.New("problem mounting overlayfs directory"), err)
}
return nil
}