diff --git a/tests/templates/globals-default.j2 b/tests/templates/globals-default.j2
index 991d16eccb..7caea7acff 100644
--- a/tests/templates/globals-default.j2
+++ b/tests/templates/globals-default.j2
@@ -27,6 +27,9 @@ docker_namespace: "kolla"
 {% if need_build_image and is_previous_release %}
 # NOTE(mgoddard): Ensure that the insecure local registry is trusted, since it
 # will be the source of images during the upgrade.
+# NOTE(yoctozepto): this is required here for CI because we run templating
+# of docker systemd command only once, using the previous release when upgrading
+# also note: atm upgrade would conflict with the zun profile which uses this var
 docker_custom_option: "--insecure-registry {{ api_interface_address }}:4000"
 {% endif %}
 {% if not is_previous_release %}