Envoy Quirks Part 2: Filter Chain Match

This is part two of a series. Envoy Quirks Part 1: Clear Route Cache Envoy Quirks Part 2: Filter Chain Match (this post) One of Envoy's core features is, of course, its ability to match traffic and route it to the appropriate destination. This is done at two levels generally: Filter Chain Matches define the top level matching of traffic, matching on attributes of the TCP and TLS handshake like port and SNI. Route Matches define the matching of HTTP traffic, matching on attributes of the HTTP request like path and headers. Filter chain matchers are notoriously tricky to get right, and have become a sort of rite of passage for Envoy users to learn how to use them correctly. Lets dig in.