As of now as an experimental feature, we added support for Thanos to enable multi-cluster Prometheus monitoring. This enables you to store your Prometheus metrics in a central place, which can be used to query, visualize metrics and write alerts based on data of multiple environments.
Thanos is very similar to Prometheus ui-wise and is integrated with Grafana and Alertmanager on the cluster where Thanos is configured.
Long term storage of Prometheus metrics is a common problem, especially when running multiple clusters. Thanos is a set of components that can be used to store and query Prometheus metrics across multiple clusters. It is a CNCF project and is widely used in the Kubernetes community.