bug: k8s dump api: /v1/discovery/kubernetes/dump return epndpoints null

[zsmlinux]

Current Behavior

discovery configuration:

    discovery:
      kubernetes:
        service:
          # apiserver schema, options [http, https]
          schema: https
          # apiserver host, options [ipv4, ipv6, domain, environment variable]
          host: ${KUBERNETES_SERVICE_HOST}

          # apiserver port, options [port number, environment variable]
          port: ${KUBERNETES_SERVICE_PORT}

        client:
          # serviceaccount token or token_file
          token_file: /var/run/secrets/kubernetes.io/serviceaccount/token

        default_weight: 50 # weight assigned to each discovered endpoint. default 50, minimum 0

        # kubernetes discovery support namespace_selector
        # you can use one of [equal, not_equal, match, not_match] filter namespace
        namespace_selector:
          # only save endpoints with namespace match one of [default, ^my-[a-z]+$]
          match:
          - ^[a-z]+$
          - alg

        # kubernetes discovery support label_selector
        # for the expression of label_selector, please refer to https://kubernetes.io/docs/concepts/overview/working-with-objects/labels
        #label_selector: |-
        #  first="a",second="b"

        # reserved lua shared memory size, 1m memory can store about 1000 pieces of endpoint
        shared_size: 20m #default 1m

        # if watch_endpoint_slices setting true, watch apiserver with endpointslices instead of endpoints
        # watch_endpoint_slices: true

When I curl dump api: curl http://127.0.0.1:9092/v1/discovery/kubernetes/dump, it return:

{"endpoints":{},"config":{"service":{"schema":"https","host":"${KUBERNETES_SERVICE_HOST}","port":"${KUBERNETES_SERVICE_PORT}"},"client":{"token_file":"/var/run/secrets/kubernetes.io/serviceaccount/token"},"namespace_selector":{"match":["^[a-z]+$","alg"]},"default_weight":50,"watch_endpoint_slices":false,"shared_size":"20m"}}

"endpoints":{}

I think some problems in it:

Expected Behavior

No response

Error Logs

No response

Steps to Reproduce

As above.

Environment

• APISIX version (run apisix version): 3.10
• Operating system (run uname -a):
• OpenResty / Nginx version (run openresty -V or nginx -V):
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info):
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):

[zsmlinux]

I have found dump api only support mutil-cluster mode, but not single-cluster mode.