github.com/gravitational/moby@v1.13.1/daemon/export.go (about)

     1  package daemon
     2  
     3  import (
     4  	"fmt"
     5  	"io"
     6  	"runtime"
     7  
     8  	"github.com/docker/docker/container"
     9  	"github.com/docker/docker/pkg/archive"
    10  	"github.com/docker/docker/pkg/ioutils"
    11  )
    12  
    13  // ContainerExport writes the contents of the container to the given
    14  // writer. An error is returned if the container cannot be found.
    15  func (daemon *Daemon) ContainerExport(name string, out io.Writer) error {
    16  	if runtime.GOOS == "windows" {
    17  		return fmt.Errorf("the daemon on this platform does not support export of a container")
    18  	}
    19  
    20  	container, err := daemon.GetContainer(name)
    21  	if err != nil {
    22  		return err
    23  	}
    24  
    25  	data, err := daemon.containerExport(container)
    26  	if err != nil {
    27  		return fmt.Errorf("Error exporting container %s: %v", name, err)
    28  	}
    29  	defer data.Close()
    30  
    31  	// Stream the entire contents of the container (basically a volatile snapshot)
    32  	if _, err := io.Copy(out, data); err != nil {
    33  		return fmt.Errorf("Error exporting container %s: %v", name, err)
    34  	}
    35  	return nil
    36  }
    37  
    38  func (daemon *Daemon) containerExport(container *container.Container) (io.ReadCloser, error) {
    39  	if err := daemon.Mount(container); err != nil {
    40  		return nil, err
    41  	}
    42  
    43  	uidMaps, gidMaps := daemon.GetUIDGIDMaps()
    44  	archive, err := archive.TarWithOptions(container.BaseFS, &archive.TarOptions{
    45  		Compression: archive.Uncompressed,
    46  		UIDMaps:     uidMaps,
    47  		GIDMaps:     gidMaps,
    48  	})
    49  	if err != nil {
    50  		daemon.Unmount(container)
    51  		return nil, err
    52  	}
    53  	arch := ioutils.NewReadCloserWrapper(archive, func() error {
    54  		err := archive.Close()
    55  		daemon.Unmount(container)
    56  		return err
    57  	})
    58  	daemon.LogContainerEvent(container, "export")
    59  	return arch, err
    60  }