moby/image/rootfs_windows.go
John Starks d45a26d7e2 Windows: Support non-base-layered images
Previously, Windows only supported running with a OS-managed base image.
With this change, Windows supports normal, Linux-like layered images, too.

Signed-off-by: John Starks <jostarks@microsoft.com>
2016-04-07 17:52:26 -07:00

48 lines
1.5 KiB
Go

// +build windows
package image
import (
"crypto/sha512"
"fmt"
"github.com/docker/distribution/digest"
"github.com/docker/docker/layer"
)
// TypeLayersWithBase is used for RootFS.Type for Windows filesystems that have layers and a centrally-stored base layer.
const TypeLayersWithBase = "layers+base"
// RootFS describes images root filesystem
// This is currently a placeholder that only supports layers. In the future
// this can be made into an interface that supports different implementations.
type RootFS struct {
Type string `json:"type"`
DiffIDs []layer.DiffID `json:"diff_ids,omitempty"`
BaseLayer string `json:"base_layer,omitempty"`
}
// BaseLayerID returns the 64 byte hex ID for the baselayer name.
func (r *RootFS) BaseLayerID() string {
if r.Type != TypeLayersWithBase {
panic("tried to get base layer ID without a base layer")
}
baseID := sha512.Sum384([]byte(r.BaseLayer))
return fmt.Sprintf("%x", baseID[:32])
}
// ChainID returns the ChainID for the top layer in RootFS.
func (r *RootFS) ChainID() layer.ChainID {
ids := r.DiffIDs
if r.Type == TypeLayersWithBase {
// Add an extra ID for the base.
baseDiffID := layer.DiffID(digest.FromBytes([]byte(r.BaseLayerID())))
ids = append([]layer.DiffID{baseDiffID}, ids...)
}
return layer.CreateChainID(ids)
}
// NewRootFSWithBaseLayer returns a RootFS struct with a base layer
func NewRootFSWithBaseLayer(baseLayer string) *RootFS {
return &RootFS{Type: TypeLayersWithBase, BaseLayer: baseLayer}
}