package daemon // import "github.com/docker/docker/daemon" import ( "fmt" "io" "github.com/docker/docker/container" "github.com/docker/docker/errdefs" "github.com/docker/docker/pkg/archive" "github.com/docker/docker/pkg/chrootarchive" "github.com/docker/docker/pkg/ioutils" ) // ContainerExport writes the contents of the container to the given // writer. An error is returned if the container cannot be found. func (daemon *Daemon) ContainerExport(name string, out io.Writer) error { ctr, err := daemon.GetContainer(name) if err != nil { return err } if isWindows && ctr.OS == "windows" { return fmt.Errorf("the daemon on this operating system does not support exporting Windows containers") } if ctr.IsDead() { err := fmt.Errorf("You cannot export container %s which is Dead", ctr.ID) return errdefs.Conflict(err) } if ctr.IsRemovalInProgress() { err := fmt.Errorf("You cannot export container %s which is being removed", ctr.ID) return errdefs.Conflict(err) } data, err := daemon.containerExport(ctr) if err != nil { return fmt.Errorf("Error exporting container %s: %v", name, err) } defer data.Close() // Stream the entire contents of the container (basically a volatile snapshot) if _, err := io.Copy(out, data); err != nil { return fmt.Errorf("Error exporting container %s: %v", name, err) } return nil } func (daemon *Daemon) containerExport(container *container.Container) (arch io.ReadCloser, err error) { rwlayer, err := daemon.imageService.GetLayerByID(container.ID) if err != nil { return nil, err } defer func() { if err != nil { daemon.imageService.ReleaseLayer(rwlayer) } }() basefs, err := rwlayer.Mount(container.GetMountLabel()) if err != nil { return nil, err } archv, err := chrootarchive.Tar(basefs, &archive.TarOptions{ Compression: archive.Uncompressed, IDMap: daemon.idMapping, }, basefs) if err != nil { rwlayer.Unmount() return nil, err } arch = ioutils.NewReadCloserWrapper(archv, func() error { err := archv.Close() rwlayer.Unmount() daemon.imageService.ReleaseLayer(rwlayer) return err }) daemon.LogContainerEvent(container, "export") return arch, err }