Admin not working in standalone mode

Description:

I set up a standalone deployment using containers by following the instructions at https://gateway.envoyproxy.io/docs/tasks/operations/standalone-deployment-mode/

Then I tried exposing port 19000 to get access to the admin interface, but it doesn't seem to work.

What issue is being seen? Describe what should be happening instead of the bug, for example: The expected value isn't returned, etc.

$ curl --verbose http://0.0.0.0:19000/
*   Trying 0.0.0.0:19000...
* Connected to 0.0.0.0 (0.0.0.0) port 19000
> GET / HTTP/1.1
> Host: 0.0.0.0:19000
> User-Agent: curl/8.7.1
> Accept: */*
> 
* Request completely sent off
* Empty reply from server
* Closing connection
curl: (52) Empty reply from server

Repro steps:

Include sample requests, environment, etc. All data and inputs required to reproduce the bug.

# docker-compose.yaml

services:
  envoy-gateway:
    image: envoyproxy/gateway:v1.3.2
    ports:
      - 8888:8888
      - 19000:19000
    volumes:
      - "./volumes/envoy-gateway:/tmp/envoy-gateway"
    command:
      - "server"
      - "--config-path"
      - "/tmp/envoy-gateway/standalone.yaml"

# standalone.conf

apiVersion: gateway.envoyproxy.io/v1alpha1
kind: EnvoyGateway
gateway:
  controllerName: gateway.envoyproxy.io/gatewayclass-controller
provider:
  type: Custom
  custom:
    resource:
      type: File
      file:
        paths: ["/tmp/envoy-gateway/config"]
    infrastructure:
      type: Host
      host: {}
logging:
  level:
    default: debug
extensionApis:
  enableBackend: true

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Environment:

Include the environment like gateway version, envoy version and so on.

See above

Logs:

Include the access logs and the Envoy logs.

No logs printed