Actually the guide you use overwrites the NodeBB config within its startup-script.
It uses the
OPENSHIFT_APP_DNS_ALIAS and fallback
OPENSHIFT_APP_DNS environment variables. So I guess those should be set by openshift and only a restart of NodeBB would be necessary.
You are using a custom script, thus that scripts author/support is the correct person to ask for troubles.
You seem to already have started a discussion at GitHub, reference: https://github.com/ahwayakchih/openshift-nodebb/issues/20
Next time, please provide more information within OP; Could've saved @PitaJ some time.