On config reload all HTTP servers are recreated and their routes are deleted even if host and port were not changed in config.
This causes an issue in metrics-export-role.
The problem is caused by using wrong fields in roles/httpd.lua:
    elseif servers[name].host ~= host or servers[name].port ~= port then
 
should be
    elseif servers[name].httpd.host ~= host or servers[name].httpd.port ~= port then