The standard buildbot model has slaves started manually. The previous section described how to configure the master for this approach.
Another approach is to let the buildbot master start slaves when builds are ready, on-demand. Thanks to services such as Amazon Web Services' Elastic Compute Cloud ("AWS EC2"), this is relatively easy to set up, and can be very useful for some situations.
The buildslaves that are started on-demand are called "latent" buildslaves. As of this writing, buildbot ships with an abstract base class for building latent buildslaves, and a concrete implementation for AWS EC2.