add better generate

Signed-off-by: Jess Frazelle <acidburn@microsoft.com>

container/image.go

@@ -0,0 +1,178 @@
+package container
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/docker/distribution/reference"
+	"github.com/docker/distribution/registry/storage"
+	"github.com/docker/distribution/registry/storage/driver/filesystem"
+	"github.com/docker/docker/pkg/archive"
+	"github.com/genuinetools/reg/repoutils"
+	bindata "github.com/jteeuwen/go-bindata"
+)
+
+// EmbedImage pulls a docker image locally. Creates a tarball of it's contents
+// and then embeds the tarball as binary data into an output bindata.go file.
+func EmbedImage(image string) error {
+	// Get the current working directory.
+	wd, err := os.Getwd()
+	if err != nil {
+		return err
+	}
+
+	// Create our output path
+	output := filepath.Join(wd, "bindata.go")
+
+	// Create the temporary directory for the image contents.
+	tmpd, err := ioutil.TempDir("", "container-lib")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(tmpd) // Cleanup on complete.
+
+	// Create our tarball path.
+	tarball := filepath.Join(tmpd, DefaultTarballPath)
+
+	// Create our image root and state.
+	root := filepath.Join(tmpd, "root")
+	state := filepath.Join(tmpd, "state")
+
+	// Create the rootfs
+	if err := createRootFS(image, root, state); err != nil {
+		return err
+	}
+
+	// Create the tar.
+	tar, err := archive.Tar(root, archive.Gzip)
+	if err != nil {
+		return fmt.Errorf("create tar failed: %v", err)
+	}
+
+	// Create the tarball writer.
+	writer, err := os.Create(tarball)
+	if err != nil {
+		return err
+	}
+	defer writer.Close() // Close the writer.
+
+	if _, err := io.Copy(writer, tar); err != nil {
+		return fmt.Errorf("copy tarball failed: %v", err)
+	}
+
+	// Create the bindata config.
+	bc := bindata.NewConfig()
+	bc.Input = []bindata.InputConfig{
+		{
+			Path:      tarball,
+			Recursive: false,
+		},
+	}
+	bc.Output = output
+	bc.Package = "main"
+	bc.NoMetadata = true
+	bc.Prefix = filepath.Dir(tarball)
+
+	if err := bindata.Translate(bc); err != nil {
+		return fmt.Errorf("bindata failed: %v", err)
+	}
+
+	return nil
+}
+
+// createRootFS creates the base filesystem for a docker image.
+// It will pull the base image if it does not exist locally.
+// This function takes in a image name and the directory where the
+// rootfs should be created.
+func createRootFS(image, rootfs, state string) error {
+	// Create the context.
+	ctx := context.Background()
+
+	// Create the new local registry storage.
+	local, err := storage.NewRegistry(ctx, filesystem.New(filesystem.DriverParameters{
+		RootDirectory: state,
+		MaxThreads:    100,
+	}))
+	if err != nil {
+		return fmt.Errorf("creating new registry storage failed: %v", err)
+	}
+
+	// Parse the repository name.
+	name, err := reference.ParseNormalizedNamed(image)
+	if err != nil {
+		return fmt.Errorf("not a valid image %q: %v", image, err)
+	}
+	// Add latest to the image name if it is empty.
+	name = reference.TagNameOnly(name)
+
+	// Get the tag for the repo.
+	_, tag, err := repoutils.GetRepoAndRef(image)
+	if err != nil {
+		return err
+	}
+
+	// Create the local repository.
+	repo, err := local.Repository(ctx, name)
+	if err != nil {
+		return fmt.Errorf("creating local repository for %q failed: %v", reference.Path(name), err)
+	}
+
+	// Create the manifest service.
+	ms, err := repo.Manifests(ctx)
+	if err != nil {
+		return fmt.Errorf("creating manifest service failed: %v", err)
+	}
+
+	// Get the specific tag.
+	td, err := repo.Tags(ctx).Get(ctx, tag)
+	// Check if we got an unknown error, that means the tag does not exist.
+	if err != nil && strings.Contains(err.Error(), "unknown") {
+		log.Println("image not found locally, pulling the image")
+
+		// Pull the image.
+		if err := pull(ctx, local, name, tag); err != nil {
+			return fmt.Errorf("pulling failed: %v", err)
+		}
+
+		// Try to get the tag again.
+		td, err = repo.Tags(ctx).Get(ctx, tag)
+	}
+	if err != nil {
+		return fmt.Errorf("getting local repository tag %q failed: %v", tag, err)
+	}
+
+	// Get the specific manifest for the tag.
+	manifest, err := ms.Get(ctx, td.Digest)
+	if err != nil {
+		return fmt.Errorf("getting local manifest for digest %q failed: %v", td.Digest.String(), err)
+	}
+
+	blobStore := repo.Blobs(ctx)
+	for i, ref := range manifest.References() {
+		if i == 0 {
+			fmt.Printf("skipping config %v\n", ref.Digest.String())
+			continue
+		}
+		fmt.Printf("unpacking %v\n", ref.Digest.String())
+		layer, err := blobStore.Open(ctx, ref.Digest)
+		if err != nil {
+			return fmt.Errorf("getting blob %q failed: %v", ref.Digest.String(), err)
+		}
+
+		// Unpack the tarfile to the mount path.
+		// FROM: https://godoc.org/github.com/moby/moby/pkg/archive#TarOptions
+		if err := archive.Untar(layer, rootfs, &archive.TarOptions{
+			NoLchown: true,
+		}); err != nil {
+			return fmt.Errorf("error extracting tar for %q: %v", ref.Digest.String(), err)
+		}
+	}
+
+	return nil
+}