routes: CheckManifest should return 404 when repo is unknown

Previously, CheckManifest() was not checking for repo not found
condition and would default to 500 status code.

Add the check now to return 404.

Fixes issue #74

pkg/api/routes.go

@@ -242,6 +242,9 @@ func (rh *RouteHandler) CheckManifest(w http.ResponseWriter, r *http.Request) {
 	_, digest, _, err := rh.c.ImageStore.GetImageManifest(name, reference)
 	if err != nil {
 		switch err {
+		case errors.ErrRepoNotFound:
+			WriteJSON(w, http.StatusNotFound,
+				NewErrorList(NewError(NAME_UNKNOWN, map[string]string{"reference": reference})))
 		case errors.ErrManifestNotFound:
 			WriteJSON(w, http.StatusNotFound,
 				NewErrorList(NewError(MANIFEST_UNKNOWN, map[string]string{"reference": reference})))

pkg/compliance/v1_0_0/check.go

@@ -474,6 +474,12 @@ func CheckWorkflows(t *testing.T, config *compliance.Config) {
 			So(resp.Header().Get("Content-Length"), ShouldEqual, "0")
 			So(resp.Header().Get(api.DistContentDigestKey), ShouldNotBeEmpty)
 
+			// check a non-existent manifest
+			resp, err = resty.R().SetHeader("Content-Type", "application/vnd.oci.image.manifest.v1+json").
+				SetBody(content).Head(baseURL + "/v2/unknown/manifests/test:1.0")
+			So(err, ShouldBeNil)
+			So(resp.StatusCode(), ShouldEqual, 404)
+
 			// create a manifest
 			m := ispec.Manifest{Layers: []ispec.Descriptor{{Digest: digest}}}
 			content, err = json.Marshal(m)