To enable exchanging information about exported services and to import these services into another mesh, we need to implement federated service discovery. Upstream Istio uses direct K8s API server access to retrieve information about services in remote clusters and to make their endpoints available locally. As our federation design implies less trust between parties, we cannot use direct k8s API server access.

This ticket covers design of the protocol as well as implementation of the server- and client-side components. Similar to k8s APIs, there will be two modes of communication:

• full sync to transfer a full set of information of exported services and
• watches to allow for fast propagation of changes.