Can configuration values be set/changed while a script executes?

You can write over the in-memory copy of the config at runtime, but it’s often hard to be sure precisely when this will have been read. In the specific case of setting the ECS cluster for cloud-aws though - there is a helper to do this: https://github.com/pulumi/pulumi-cloud/blob/master/aws/config/index.ts#L190.

👍 !