How to dynamically update session hosts in an existing host pool

Do you have an existing Windows Virtual Desktop where you want to replace the session host virtual machines with new images? 

You could build a new host pool with the new session host VM’s and present the new icon to users and get them to test and then switch them over. That’s not ideal as users need to launch this new desktop which could lead to confusion. 

However what you can now do is use an “update” ARM template to dynamically replace the VM’s in the existing host pool with no other changes being made to it and no or very little user interaction. 

This template actually builds any number of new session hosts into the same host pool, and then will either deallocate or delete the existing VM’s. If you choose delete it will delete the VM’s and related storage which means there will be no residual costs related to the VM’s. It also deletes all other infrastructure components. It will also send a message to all conencted user sessions.

Have a look at this video which goes through the process: 

The ARM template is stored in this Github repo.