Only pass the project if it is specified

builder/openstack/access_config.go

@@ -40,10 +40,13 @@ func (c *AccessConfig) Auth() (gophercloud.AccessProvider, error) {
 	authoptions := gophercloud.AuthOptions{
 		Username:    username,
 		Password:    password,
-		TenantName:  project,
 		AllowReauth: true,
 	}
 
+	if project != "" {
+		authoptions.TenantName = project
+	}
+
 	return gophercloud.Authenticate(provider, authoptions)
 }