Envoy proxy listener for catching all traffic

In a k8s cluster i need to setup keycloak with a second keycloak as an identity provider.
The problem is that i need to make traffic towards the second keycloak to go through a second envoy which acts as
service mesh entry point and load balancer.

I have found a working solution but it is too complex.
I need to get rid of this envoy listener which listens on requests towards 127.0.0.1 and 9090

  - name: idp
    address:
      socket_address:
        address: 127.0.0.1
        ipv4_compat: true
        port_value: 9090
        protocol: TCP
    filter_chains:
      filters:
      - name: envoy.filters.network.tcp_proxy
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.tcp_proxy.v3.TcpProxy
          stat_prefix: idp
          cluster: envoylb
          access_log:
          - name: envoy.access_loggers.file
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.access_loggers.file.v3.FileAccessLog
              path: "/var/log/envoysidecar.log"

and replace it with one that catches all traffic and forwards it to the envoylb cluster

  - name: envoylb
    type: STRICT_DNS
    connect_timeout:
      seconds: 15552000
    lb_policy: ROUND_ROBIN
    load_assignment:
      cluster_name:  envoylb
      endpoints:
      - lb_endpoints:
        - endpoint:
            address:
              socket_address:
                address: envoylbservice
                port_value: 8298

I tried several things but nothing seems to work.

Not sure from the question what you try to obtain.
Envoy config.core.v3.SocketAddress must have once specific port to listen.
For the address, you can use 0.0.0.0 to bind any address.

Then by using the filter envoy.filters.network.tcp_proxy envoy can passthrough all the requests from this specific port the desired cluster.

Example:

static_resources:
  listeners:
    - name: idp
      address:
        socket_address:
          address: 0.0.0.0
          port_value: 9090
      filter_chains:
        - filters:
            - name: envoy.filters.network.tcp_proxy
              typed_config:
                "@type": type.googleapis.com/envoy.extensions.filters.network.tcp_proxy.v3.TcpProxy
                stat_prefix: destination
                cluster: envoylb
  clusters:
    - name: envoylb
      type: STRICT_DNS
      connect_timeout:
         seconds: 15552000
      lb_policy: ROUND_ROBIN
      load_assignment:
        cluster_name: envoylb
        endpoints:
          - lb_endpoints:
              - endpoint:
                  address:
                    socket_address:
                      address: envoylbservice
                      port_value: 8298