fix registry remove image (#50)

registry/delete.go

@@ -3,24 +3,55 @@ package registry
 import (
 	"fmt"
 	"net/http"
+
+	"github.com/docker/distribution/manifest/schema2"
 )
 
 // Delete removes a repository reference from the registry.
+// https://docs.docker.com/registry/spec/api/#deleting-an-image
 func (r *Registry) Delete(repository, ref string) error {
+	// get digest first
 	url := r.url("/v2/%s/manifests/%s", repository, ref)
-	r.Logf("registry.manifests.delete url=%s repository=%s ref=%s", url, repository, ref)
+	r.Logf("registry.manifests.get url=%s repository=%s ref=%s",
+		url, repository, ref)
 
-	req, err := http.NewRequest("DELETE", url, nil)
+	req, err := http.NewRequest("GET", url, nil)
 	if err != nil {
 		return err
 	}
+	req.Header.Set("Accept", schema2.MediaTypeManifest)
 
 	resp, err := r.Client.Do(req)
 	if err != nil {
 		return err
 	}
 	defer resp.Body.Close()
 
+	digest := resp.Header.Get("Docker-Content-Digest")
+	if resp.StatusCode != http.StatusOK {
+		if resp.StatusCode == http.StatusNotFound {
+			return nil
+		}
+		return fmt.Errorf("Got status code: %d", resp.StatusCode)
+	}
+
+	// delete image
+	url = r.url("/v2/%s/manifests/%s", repository, digest)
+	r.Logf("registry.manifests.delete url=%s repository=%s ref=%s",
+		url, repository, digest)
+
+	req, err = http.NewRequest("DELETE", url, nil)
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("Accept", schema2.MediaTypeManifest)
+	resp, err = r.Client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
 	if resp.StatusCode == http.StatusAccepted || resp.StatusCode == http.StatusNotFound {
 		return nil
 	}