Gracefully remove real server from load balancing with health monitor?
We have a pair of Fortigate 1500d in an active/active configuration in our new datacenter and will have numerous websites load balanced behind them. Our software development team is now setting up the automation of web application deployments in this new datacenter and their plan was to handle it the same way we do in our current datacenter, by renaming a file on the web server that is being monitored by a health monitor and having the load balancer take it offline. While the Fortigate can do this part, we discovered it's immediately taking the real server offline breaking session state.
Is there anyway to have a health monitor gracefully take a real server offline and prevent new sessions, but let current sessions wrap up? This is how our current load balancer works.
If the above is not an option, does the Fortigate offer an API where automation can gracefully take a real server offline for updates.
Denny