subgraph cluster_istioagent {
        label = "Istio Agent"
        color="orange"
        sds
        SecretManager -> caClient [label="Sign CSR"]
        caClient -> grpc
        grpc -> TokenProvider [dir=none,label="Fetch JWT",color=purple]
        grpc -> cfiles [dir=none,label="Fetch Cert",color=purple]

        sds -> SecretManager [label="Generate certificate"]

1. The `caClient` will be configured to use either JWT or mTLS authentication. For JWT authentication, gRPC's `PerRPCCredentials`
   is configured with a `TokenProvider` which handles the logic of adding the proper JWT to each request. mTLS is configured
   by a tls.Config that points to files on disk.