Federated Kubernetes Access with Trusted Clusters

When multiple Trusted Clusters are present behind the Teleport Proxy Service, the kubeconfig generated by tsh login will contain the Kubernetes API endpoint determined by the <cluster> argument to tsh login.

For example, consider the following setup:

• There are three Teleport/Kubernetes clusters: main, east, and west. These are the names set in cluster_name setting in their configuration files.
• The clusters east and west are Trusted Clusters for main.
• Users always authenticate against main but use their certificates to access SSH nodes and the Kubernetes API in all three clusters.
• The DNS name of the main Proxy Service is main.example.com.

In this scenario, users usually log in using this command:

Using login without arguments
tsh --proxy=main.example.com login
User's `kubeconfig` now contains one entry for the main Kubernetes
endpoint, i.e. `main.example.com`.
Receive a certificate for "east":
tsh --proxy=main.example.com login east
User's `kubeconfig` now contains the entry for the "east" Kubernetes
endpoint, i.e. `east.main.example.com`.