How to config layered_runtime bootstrap

1 
apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: ef-bootstrap
spec:
  workloadSelector:
    labels:
      app: productpage
  configPatches:
  - applyTo: BOOTSTRAP
    patch:
      operation: MERGE
      value:
          layered_runtime: 
            layers:
            - name: "rtds_layer"
              rtds_layer: 
                name: rtds
                rtds_config:
                  ads: {}
                  resource_api_version: V3
                  initial_fetch_timeout: 0s

Readiness probe failed: Get “http://172.20.1.9:15021/healthz/ready”: dial tcp 172.20.1.9:15021: connect: connection refused
the rtds_layer name is the subscribed resource name,does here have any problem?