How we migrated Bitbucket Cloud to Envoy proxy

This post details the migration of Bitbucket Cloud's edge load balancing and proxy solution from a previous single-region, non-auto-scaling system to Envoy Proxy. Key technical contributions include: introduction of self-hosted Varnish Cache for HTTP traffic caching, translation of thousands of lines of Perl-based routing logic into Envoy and Varnish configurations, implementation of global rate limiting with per-tenant policies via Envoy contributions, addition of SSH and IPv6 support through Envoy's TCP proxying and IPv6 termination capabilities, and a phased migration strategy using weighted DNS records and dogfooding with Atlassian-originated traffic. Performance gains include reduced latency for non-US-based clients and elastic scalability.