We have recently implemented the Duo Access Gateway, and part of setting up any critical IT service is making sure the service is highly available. Duo has a great install doc, and they provide support for using a load balancer in front of your DAGs, but right now any configuration changes must be manually synced to each DAG.
To automate configuration synchronization, I have built some bash scripts that replicate any config changes from a “primary” DAG to any number of secondary DAGs: https://github.com/dkuchenski/duo-security/tree/master/scripts
Feel free to use and change as needed. Or if there are other solutions out there, please let me know!
Note: This is only for Ubuntu 16.04