In kubernetes cluster, with istio running, I have deployed sample authorization service with jwt policy. Making a curl request works as expected. Now, I need to make an external authorization callout with dummy api to test out my authorization service. I created virtualservice, destinationrule etc. I also deployed istio envoy filter with details:

  filters:
    - filterConfig:
        httpService:
          authorizationRequest:
            allowedHeaders:
              patterns:
                - exact: authorization
          serverUri:
            cluster: outbound|8080||authservice.default.svc.cluster.local
            timeout: 5.000s
            uri: http://authservice.default.svc.cluster.local:8080
      filterName: envoy.ext_authz
      filterType: HTTP

But after running envoy filter I get 503 service unavailable. I tried chaning the namespace in envoyffilter but still the same error. Please let me know anyway to achieve service callout with filter envoy.ext_authz.