Initial untar working

Author: clareliguori

.gitignore

@@ -0,0 +1,16 @@
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+vendor/
+
+image-output/

main.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/containers/image/image"
+	"github.com/containers/image/pkg/blobinfocache"
+	"github.com/containers/image/transports/alltransports"
+	"github.com/containers/image/types"
+	"github.com/pkg/errors"
+)
+
+func main() {
+	err := ConvertImage("docker-daemon:lambda-php:latest")
+	if err != nil {
+		fmt.Printf("Error: %+v", err)
+		os.Exit(1)
+	}
+}
+
+func ConvertImage(name string) (retErr error) {
+	// Get image's layer data from image name
+	ref, err := alltransports.ParseImageName(name)
+	if err != nil {
+		return err
+	}
+
+	sys := &types.SystemContext{}
+
+	ctx := context.Background()
+
+	cache := blobinfocache.DefaultCache(sys)
+
+	rawSource, err := ref.NewImageSource(ctx, sys)
+	if err != nil {
+		return err
+	}
+
+	src, err := image.FromSource(ctx, sys, rawSource)
+	if err != nil {
+		if closeErr := rawSource.Close(); closeErr != nil {
+			return errors.Wrapf(err, " (close error: %v)", closeErr)
+		}
+
+		return err
+	}
+	defer func() {
+		if err := src.Close(); err != nil {
+			retErr = errors.Wrapf(retErr, " (close error: %v)", err)
+		}
+	}()
+
+	layerInfos := src.LayerInfos()
+
+	dir, err := os.Getwd()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Unpack each layer onto disk
+	for _, layerInfo := range layerInfos {
+		blobStream, _, err := rawSource.GetBlob(ctx, layerInfo, cache)
+		if err != nil {
+			return err
+		}
+
+		imageDir := filepath.Join(dir, "image-output", name, string(layerInfo.Digest))
+
+		if err := os.MkdirAll(imageDir, 0777); err != nil {
+			return err
+		}
+
+		fmt.Printf("Layer %s, size %d, media type %s\n", layerInfo.Digest, layerInfo.Size, layerInfo.MediaType)
+		fmt.Printf("Dir %s\n", imageDir)
+
+		tarCmd := exec.Command("tar", "-p", "-x", "-C", imageDir)
+		tarCmd.Stdin = blobStream
+		if output, err := tarCmd.CombinedOutput(); err != nil {
+			fmt.Printf("combined out:\n%s\n", string(output))
+			return err
+		}
+
+		blobStream.Close()
+	}
+
+	return nil
+}