503 : Service Unavailable z2jh

JupyterHub Zero to JupyterHub on Kubernetes
1

hello,

I followed the instruction in the example here Services — Zero to JupyterHub with Kubernetes documentation to create a hub-managed service. Here is part of my values.yaml

proxy:
  chp:
     networkPolicy:
       egress:
            - to:
                  - podSelector:
                      matchLabels:
                             app: jupyterhub
                             component: hub
            ports:
                  - port: 9000
hub:
  networkPolicy:
    ingress:
      - ports:
              - port: 9000
        from:
              - podSelector:
                   hub.jupyter.org/network-access-hub: "true"
  service:
            extraPorts:
                    - port: 9000
                      targetPort: 9000
                      name: some_course_here
  extraConfig:
    init: |
      # some code here    

      c.JupyterHub.services.append(
            {
              "name": course,
              "url": f"http://hub:9000",
              "command": ["jupyterhub-singleuser", f"--group=formgrade-{course}",
 "--port=9000", "--debug"],
              "oauth_no_confirm": True,
              "environment" : {
                "JUPYTERHUB_USER": "admin",
                'JUPYTERHUB_DEFAULT_URL': '/lab'
              }
            }

What’s the issue? I get 503: service unavailable in the browser when I try to redirect to service /services/course_name
what is exactly happening?

best