We try to avoid microservices wherever possible. If we're adding something new, it typically starts off as part of the service being deployed - either as a container within the pod (we use kubernetes) or as a library that the code can use. If something grows big enough in a way that it can't scale with the service it's running with, we split it into a separate service. The opposite is also true - if a service that we run no longer warrants a separate deployment, we make it a container or a library. We use GRPC for most communication and interfaces for anything that travels package boundaries. Both of these help with making the split/aggregation a lot easier to manage.