10.244.0.195:9080                                HEALTHY                  outbound|9080||reviews.default.svc.cluster.local
./var/run/secrets/workload-spiffe-uds/socket     HEALTHY                  sds-grpc
10.244.0.188:11800                               HEALTHY                  outbound|11800||skywalking-oap.skywalking.svc.cluster.local

  admin: warning
  aws: warning
  assert: warning
  backtrace: warning
  client: warning
  config: warning
  connection: warning
  dubbo: warning
  file: warning
  filter: warning
  forward_proxy: warning
  grpc: warning
  hc: warning
  health_checker: warning
  http: warning
  http2: warning
  hystrix: warning
  init: warning
  io: warning
  jwt: warning
  kafka: warning
  lua: warning
  main: warning

github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0 h1:Ovs26xHkKqVztRpIrF/92BcuyuQ/YW4NSIpoGtfXNho=
github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgfV/d3M/q6VIi02HzZEHgUlZvzk=
github.com/grpc-ecosystem/grpc-gateway v1.9.0/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=
github.com/grpc-ecosystem/grpc-gateway v1.9.5/go.mod h1:vNeuVxBJEsws4ogUvrchl83t/GYV9WGTSLVdBhOQFDY=

            value:
              mountPath: /mnt/path1
              name: my-volume-name
        - kind: Service
          name: istio-pilot
          patches:
          - path: spec.ports.[name:grpc-xds].port
            value: 15099 # OVERRIDDEN
```

The user-defined overlay uses a path spec that includes the ability to select list items by key. In the example above,

   1. `SecretManager` can also read certificates from files. When this is configured, no CA client is used.
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.

## Proxy Configuration

Istiod's primary role - and most code - is to dynamically configure proxies (Envoy sidecars and ingress, gRPC, ztunnel, and more). This roughly consists of 3 parts:
1. Config ingestion (inputs to the system)
1. Config translation
1. Config serving (XDS)

### Config Ingestion

}

message GRPCAction {
  // Port number of the gRPC service. Number must be in the range 1 to 65535.
  optional int32 port = 1;

  // Service is the name of the service to place in the gRPC HealthCheckRequest
  // (see https://github.com/grpc/grpc/blob/master/doc/health-checking.md).
  //
  // If this is not specified, the default behavior is defined by gRPC.
  // +optional
  // +default=""