EDIT:
The guide has been updated since the writing of this post, no need to hack files
https://github.com/NodeBB/nodebb-english/blob/master/installing/cloud/openshift.rst
It worked for me aswell, didn't have the chance to debug and fix it otherwise.
I think it might be useful for other people to know how to fix it
Get the value of the ENV_VAR
echo $OPENSHIFT_NODEJS_IP
and put it at line 104 of src/webserver.js as follow
//args = isSocket ? [port] : [port, nconf.get('bind_address')],
args = [8080, "127.0.0.1"],