try fetch auth for default docker registiry urls

core/common.go

@@ -251,7 +251,7 @@ func buildPullOptions(image string) (docker.PullImageOptions, docker.AuthConfigu
 	return docker.PullImageOptions{
 		Repository: repository,
 		Registry:   registry,
-		Tag:	tag,
+		Tag:        tag,
 	}, buildAuthConfiguration(registry)
 }
 
@@ -274,6 +274,20 @@ func buildAuthConfiguration(registry string) docker.AuthConfiguration {
 		return auth
 	}
 
-	auth, _ = dockercfg.Configs[registry]
+	if v, ok := dockercfg.Configs[registry]; ok {
+		return v
+	}
+
+	// try to fetch configs from docker hub default registry urls
+	// see example here: https://www.projectatomic.io/blog/2016/03/docker-credentials-store/
+	if registry == "" {
+		if v, ok := dockercfg.Configs["https://index.docker.io/v2/"]; ok {
+			return v
+		}
+		if v, ok := dockercfg.Configs["https://index.docker.io/v1/"]; ok {
+			return v
+		}
+	}
+
 	return auth
 }