Apache Stratos provides a load balancer extension API which could be implemented for supporting third party load balancers. Via this extension API a load balancer could fetch the topology in real time and update its configuration accordingly. A reference implementation of this extension has been done for HAProxy .
The idea of the project is to implement a similar extension to support Google Compute Engine Load Balancing service  via its CLI or API.
If there is an interest on doing this project please send a mail to imesh at apache dot org by copying Apache Stratos Dev mailing list .