envoy

Let me start by saying: The gotchas that we've experienced have been far eclipsed by the benefits. Aside from what what discussed, there weren't many things with Envoy specifically. We did have a few minor issues with the Thrift tooling, e.g. https://github.com/envoyproxy/envoy/commit/a3c744294bca2cbf6... but as the above indicates, they were resolved _very_ quickly. The most important thing when making a transition like this is to have as much monitoring and observability as possible without the new tech. We were able to quickly identify and respond to issues we had with Envoy based on existing application and system instrumentation that weren't directly provided by Envoy, along with the vigilance of our engineering team.