type CentralControlPlaneOptions struct {
	// Xds is XDS endpoint, e.g. localhost:15010.
	Xds string

	// XdsPodLabel is a Kubernetes label on the Istiod pods
	XdsPodLabel string

	// XdsPodPort is a port exposing XDS (typically 15010 or 15012)
	XdsPodPort int

	// CertDir is the local directory containing certificates
	CertDir string

	// Timeout is how long to wait before giving up on XDS
	Timeout time.Duration

	"text/tabwriter"

	"github.com/spf13/cobra"

	"istio.io/istio/istioctl/pkg/cli"
	"istio.io/istio/istioctl/pkg/clioptions"
	"istio.io/istio/pkg/cluster"
)

// TODO move to multicluster package; requires exposing some private funcs/vars in this package
func ClustersCommand(ctx cli.Context) *cobra.Command {
	var opts clioptions.ControlPlaneOptions
	cmd := &cobra.Command{
		Use:   "remote-clusters",

![CA Flow](docs/ca.svg)

A single SDS request from Envoy goes through a few different layers in istio-agent.

1. First, the request is handled by the SDS server. This is mostly just an intermediate translation layer exposing
   the `SecretManager` to Envoy, without much business logic. For each resource requested by Envoy, the SDS server
   will call `SecretManager.GenerateSecret(resourceName)`