I highly recommend this tool. Yelp has used it in production for years to manage a fairly large PaaS (hundreds of services, thousands of containers, constant churn); it's proven quite flexible and resilient.
Synapse is available on github [0], and we've open sourced our automation used to create a highly available service router using Synapse as well [1][2].
Really appreciate not only the work put into Synapse, but also the release and maintenance of it. Its been very helpful for projects where I've used it.