Lyft's deployment of Envoy, an out-of-process proxy, serves as a case study in transitioning from a monolithic architecture to a microservices ecosystem, highlighting the complexities of integrating a service mesh into existing infrastructure. The presentation covers the step-by-step process of Envoy's implementation, from its initial role as an edge proxy to becoming integral to the monolithic core, and eventually expanding throughout the service architecture. A significant focus is placed on the evolution of Envoy's configuration management, moving from static JSON configurations to a more dynamic, API-driven approach, with future plans for further decentralization. The talk also emphasizes the complementary role of Istio in separating control and data planes, which offers a more scalable solution for managing microservices. The session concludes with discussions on future trends like global load balancing and centralized health checking, alongside a Q&A on network latency, configuration practices, and Envoy's strategic direction within the CNCF.