Matt, thank you for clarification.
Actually EC2 instance run single (default) agent. The only purpose of it is to have a server with at least one agent connected from scratch.
In real life user should configure agents cloud with a help of one of related plugins:
–
https://confluence.jetbrains.com/display/TCD9/Setting+Up+TeamCity+for+Amazon+EC2
– https://plugins.jetbrains.com/plugin/10067-amazon-ecs-support
– https://blog.jetbrains.com/teamcity/2017/10/teamcity-kubernetes-support-plugin/
– etc.
By the way, all of those plugins support terminating agent after every build.
As for using power of ECS – we plan to provide HA (high available) TeamCity server installation in the future, so ECS will be used to run two instances of server. In current version usage of ECS looks like a big overhead.
Again, feel free to use ECS to run agents with ECS support plugin https://plugins.jetbrains.com/plugin/10067-amazon-ecs-support