Observability is complicated and multi-faceted by nature. When you multiply that with a multi-cluster in play, the complexity can seem untameable. Service Mesh solutions could seem like they are the key to solving such a daunting task. They would make multi-cluster handling hidden away, and observability setup provided by default. So, is Service Mesh a silver bullet for any complex Observability requirements? No, it isn't - in fact, it can actually make things more complicated. Ryota has been running Istio since its v1.1 release in production. He will share how Istio helped in many areas, and also highlight some parts that he had trouble with, such as cross-cluster trace and metrics. We will then take a step back with Prometheus basics, understand what Istio does by default, and find the gaps. With the challenges of alert handling, high cardinality, remote read/write, we will wrap up with a demo of how such a multi-cluster Observability setup can be achieved using Istio, Prometheus Operator, and Thanos.