add cmd/mirror, revert cmd/api changes

pkg/serve/error.go

@@ -4,6 +4,8 @@ import (
 	"encoding/json"
 	"errors"
 	"net/http"
+
+	"github.com/google/go-containerregistry/pkg/v1/remote/transport"
 )
 
 var (
@@ -14,6 +16,11 @@ var (
 func Error(w http.ResponseWriter, err error) {
 	code := "INTERNAL_ERROR"
 	httpCode := http.StatusInternalServerError
+	if terr, ok := err.(*transport.Error); ok {
+		http.Error(w, "", terr.StatusCode)
+		json.NewEncoder(w).Encode(terr.Errors)
+		return
+	}
 
 	if err == ErrNotFound {
 		code = "MANIFEST_UNKNOWN"

pkg/serve/serve.go

@@ -21,6 +21,16 @@ func Blob(w http.ResponseWriter, r *http.Request, digest string) {
 	http.Redirect(w, r, url, http.StatusSeeOther)
 }
 
+func BlobExists(h v1.Hash) error {
+	ctx := context.Background() // TODO
+	client, err := storage.NewClient(ctx)
+	if err != nil {
+		return fmt.Errorf("NewClient: %v", err)
+	}
+	_, err = client.Bucket(bucket).Object(fmt.Sprintf("blobs/%s", h)).Attrs(ctx)
+	return err
+}
+
 func writeBlob(h v1.Hash, rc io.ReadCloser, contentType string) error {
 	ctx := context.Background() // TODO
 	client, err := storage.NewClient(ctx)
@@ -56,7 +66,7 @@ func writeBlob(h v1.Hash, rc io.ReadCloser, contentType string) error {
 	return nil
 }
 
-// ServeManifest writes config and layer blobs for the image, then serves the
+// Manifest writes config and layer blobs for the image, then serves the
 // manifest contents pointing to those blobs.
 func Manifest(w http.ResponseWriter, r *http.Request, img v1.Image) {
 	// Write config blob for later serving.