Add rootfs command to dist

Commands allows preparing a rootfs from a manifest hash

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

cmd/containerd/main.go

@@ -19,6 +19,7 @@ import (
 	"github.com/docker/containerd"
 	contentapi "github.com/docker/containerd/api/services/content"
 	api "github.com/docker/containerd/api/services/execution"
+	rootfsapi "github.com/docker/containerd/api/services/rootfs"
 	"github.com/docker/containerd/content"
 	"github.com/docker/containerd/log"
 	"github.com/docker/containerd/plugin"
@@ -366,6 +367,8 @@ func interceptor(ctx gocontext.Context,
 		ctx = log.WithModule(ctx, "execution")
 	case contentapi.ContentServer:
 		ctx = log.WithModule(ctx, "content")
+	case rootfsapi.RootFSServer:
+		ctx = log.WithModule(ctx, "rootfs")
 	default:
 		fmt.Printf("unknown GRPC server type: %#v\n", info.Server)
 	}

cmd/dist/main.go

@@ -69,6 +69,7 @@ distribution tool
 		deleteCommand,
 		listCommand,
 		applyCommand,
+		rootfsCommand,
 	}
 	app.Before = func(context *cli.Context) error {
 		var (

cmd/dist/rootfs.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"io/ioutil"
+
+	contentapi "github.com/docker/containerd/api/services/content"
+	rootfsapi "github.com/docker/containerd/api/services/rootfs"
+	"github.com/docker/containerd/content"
+	"github.com/docker/containerd/log"
+	contentservice "github.com/docker/containerd/services/content"
+	rootfsservice "github.com/docker/containerd/services/rootfs"
+	digest "github.com/opencontainers/go-digest"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/urfave/cli"
+)
+
+var rootfsCommand = cli.Command{
+	Name:  "rootfs",
+	Usage: "rootfs setups a rootfs",
+	Subcommands: []cli.Command{
+		rootfsPrepareCommand,
+	},
+}
+
+var rootfsPrepareCommand = cli.Command{
+	Name:      "prepare",
+	Usage:     "prepare applies layers from a manifest to a snapshot",
+	ArgsUsage: "[flags] <digest>",
+	Flags:     []cli.Flag{},
+	Action: func(clicontext *cli.Context) error {
+		var (
+			ctx = background
+		)
+
+		dgst, err := digest.Parse(clicontext.Args().First())
+		if err != nil {
+			return err
+		}
+
+		log.G(ctx).Infof("preparing manifest %s", dgst.String())
+
+		conn, err := connectGRPC(clicontext)
+		if err != nil {
+			return err
+		}
+
+		provider := contentservice.NewProviderFromClient(contentapi.NewContentClient(conn))
+		m, err := resolveManifest(ctx, provider, dgst)
+		if err != nil {
+			return err
+		}
+
+		preparer := rootfsservice.NewPreparerFromClient(rootfsapi.NewRootFSClient(conn))
+		chainID, err := preparer.Prepare(ctx, m.Layers)
+		if err != nil {
+			return err
+		}
+
+		log.G(ctx).Infof("chain ID: %s", chainID.String())
+
+		return nil
+	},
+}
+
+func resolveManifest(ctx context.Context, provider content.Provider, dgst digest.Digest) (ocispec.Manifest, error) {
+	p, err := readAll(ctx, provider, dgst)
+	if err != nil {
+		return ocispec.Manifest{}, err
+	}
+
+	// TODO(stevvooe): This assumption that we get a manifest is unfortunate.
+	// Need to provide way to resolve what the type of the target is.
+	var manifest ocispec.Manifest
+	if err := json.Unmarshal(p, &manifest); err != nil {
+		return ocispec.Manifest{}, err
+	}
+
+	return manifest, nil
+}
+
+func readAll(ctx context.Context, provider content.Provider, dgst digest.Digest) ([]byte, error) {
+	rc, err := provider.Reader(ctx, dgst)
+	if err != nil {
+		return nil, err
+	}
+	defer rc.Close()
+
+	return ioutil.ReadAll(rc)
+}