Migrating Millions of Concurrent Websockets to Envoy - Great writeup from the Slack engineering team of their migration from HAProxy to Envoy Proxy, web sockets are amazing for anything real-time but there is added complexity because of the constant data moving in both directions, that makes debugging more difficult than REST APIs, their migration took several months but it was transparent to users, which is quite an achievement, especially because of the scale of their operationslack.engineering #