Lyft announced a major open source project in 2016, called Envoy. Envoy is a high-performance service bus for SOA, that abstracts details of the network layer and makes it easy to optimize traffic and see hotspots.

Before Envoy, Lyft used Amazon ELB for service discover and load balancing, a variety of PHP and Python apps, and some HAProxy where performance was critical. At just 30 services, enough sporadic network issues happened that the team decided to build something new, a way to get real network transparency even in a variable environment like Amazon EC2.

In an Envoy setup, each app connects through localhost, where a self-contained Envoy process is listening and then routing the traffic. The network is invisible to the app, in other words.