The docs at https://www.openshift.com/developers/scaling claim "All of the standard OpenShift web cartridges are scalable using HAProxy, with the exception of the Do-It-Yourself and Jenkins cartridges." The link for "web cartridges" goes to a list which contains Zend. However AFAIK Zend is not currently scalable.
We apologize, however, we do not plan to address this report at this time. The majority of our active development is for the v3 version of OpenShift. If you would like for Red Hat to reconsider this decision, please reach out to your support representative. We are very sorry for any inconvenience this may cause.