Hello,
Nothing changes from the licensing point of view. You still need a license for each authorized agent.
If you’re already running agents on vSphere then you probably manage them manually or you have to write custom scripts to do that. This plugin simplifies agent management process.
First TeamCity will start agents based on current demand, thus leaving more resources to other virtual machines on vSphere.
Secondly, since VM instances are started/stopped/authorized automatically, if you need to update software all you need to do is update image and tell TeamCity which snapshot to use. If you do that manually, you’ll have to restart instances in vSphere one by one (and do not forget to check whether a build is running there). This is tedious and not easy to do even if you automate this task.
If you have 10 agents, this plugin probably does not add much value. But for 100 agents and more, plugin value becomes more apparent.