ing requirements precipitated Auto Trader UK&rsquo;s migration to containerized applications using Istio as a service mesh. One of the most pressing reasons was the recent focus on GDPR. AutoTrader wasn’t satisfied with just typical perimeter security. It aspired to also encrypt all traffic between microservices, even those in the same local network, using mutual-TLS. The effort felt significant for a primarily custom-built on-premises private cloud infrastructure operating at Auto Trader’s large scale.