implement raw pullimage functionality

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

cmd/client/main.go

@@ -32,6 +32,7 @@ func main() {
 
 	app.Commands = []cli.Command{
 		runtimeVersionCommand,
+		pullImageCommand,
 	}
 
 	if err := app.Run(os.Args); err != nil {
@@ -39,6 +40,35 @@ func main() {
 	}
 }
 
+func PullImage(client pb.ImageServiceClient, image string) error {
+	_, err := client.PullImage(context.Background(), &pb.PullImageRequest{Image: &pb.ImageSpec{Image: &image}})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// try this with ./ocic pullimage docker://busybox
+var pullImageCommand = cli.Command{
+	Name:  "pullimage",
+	Usage: "pull an image",
+	Action: func(context *cli.Context) error {
+		// Set up a connection to the server.
+		conn, err := grpc.Dial(address, grpc.WithInsecure())
+		if err != nil {
+			return fmt.Errorf("Failed to connect: %v", err)
+		}
+		defer conn.Close()
+		client := pb.NewImageServiceClient(conn)
+
+		err = PullImage(client, context.Args().Get(0))
+		if err != nil {
+			return fmt.Errorf("pulling image failed: %v", err)
+		}
+		return nil
+	},
+}
+
 var runtimeVersionCommand = cli.Command{
 	Name:  "runtimeversion",
 	Usage: "get runtime version information",

server/image.go

@@ -1,23 +1,95 @@
 package server
 
 import (
+	"errors"
+	"os"
+
+	"github.com/containers/image/directory"
+	"github.com/containers/image/image"
+	"github.com/containers/image/transports"
 	pb "github.com/kubernetes/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
 	"golang.org/x/net/context"
 )
 
 // ListImages lists existing images.
 func (s *Server) ListImages(ctx context.Context, req *pb.ListImagesRequest) (*pb.ListImagesResponse, error) {
+	// TODO
+	// containers/storage will take care of this by looking inside /var/lib/ocid/images
+	// and listing images.
 	return nil, nil
 }
 
 // ImageStatus returns the status of the image.
 func (s *Server) ImageStatus(ctx context.Context, req *pb.ImageStatusRequest) (*pb.ImageStatusResponse, error) {
+	// TODO
+	// containers/storage will take care of this by looking inside /var/lib/ocid/images
+	// and getting the image status
 	return nil, nil
 }
 
 // PullImage pulls a image with authentication config.
 func (s *Server) PullImage(ctx context.Context, req *pb.PullImageRequest) (*pb.PullImageResponse, error) {
-	return nil, nil
+	img := req.GetImage().GetImage()
+	if img == "" {
+		return nil, errors.New("got empty imagespec name")
+	}
+
+	// TODO(runcom): deal with AuthConfig in req.GetAuth()
+
+	// TODO(mrunalp,runcom): why do we need the SandboxConfig here?
+	// how do we pull in a specified sandbox?
+	tr, err := transports.ParseImageName(img)
+	if err != nil {
+		return nil, err
+	}
+	// TODO(runcom): figure out the ImageContext story in containers/image instead of passing ("", true)
+	src, err := tr.NewImageSource("", true)
+	if err != nil {
+		return nil, err
+	}
+	i := image.FromSource(src, nil)
+	blobs, err := i.BlobDigests()
+	if err != nil {
+		return nil, err
+	}
+	// TODO: make sure this dir exists?
+	if err := os.Mkdir("/var/lib/ocid/images/"+tr.StringWithinTransport(), 0755); err != nil {
+		return nil, err
+	}
+	dir, err := directory.NewReference("/var/lib/ocid/images/" + tr.StringWithinTransport())
+	if err != nil {
+		return nil, err
+	}
+	// TODO(runcom): figure out the ImageContext story in containers/image instead of passing ("", true)
+	dest, err := dir.NewImageDestination("", true)
+	if err != nil {
+		return nil, err
+	}
+	// save blobs (layer + config for docker v2s2, layers only for docker v2s1 [the config is in the manifest])
+	for _, b := range blobs {
+		// TODO(runcom,nalin): we need do-then-commit to later purge on error
+		r, _, err := src.GetBlob(b)
+		if err != nil {
+			return nil, err
+		}
+		if err := dest.PutBlob(b, r); err != nil {
+			r.Close()
+			return nil, err
+		}
+		r.Close()
+	}
+	// save manifest
+	m, _, err := i.Manifest()
+	if err != nil {
+		return nil, err
+	}
+	if err := dest.PutManifest(m); err != nil {
+		return nil, err
+	}
+
+	// TODO: what else do we need here? (Signatures when the story isn't just pulling from docker://)
+
+	return &pb.PullImageResponse{}, nil
 }
 
 // RemoveImage removes the image.