Ingress with a subpath has a hard-coded trailing slash

[johnflavin]

Bug description

I am trying to deploy JH to a subpath, e.g. <mydomain>/jupyter. I set hub.baseUrl=/jupyter and enable ingress, but the Ingress object is not correctly configured, it has a trailing slash: path: /jupyter/.

How to reproduce

Use helm to install jupyter with ingress enabled and a subpath on hub.baseUrl.

helm upgrade --install \
	jupyter jupyterhub/jupyterhub \
	--namespace jupyter \
	--version=4.1.0 \
	--set proxy.service.type=ClusterIP \
	--set hub.baseUrl=/jupyter \
	--set ingress.enabled=true,ingress.hosts="{<mydomain>}"

Expected behaviour

Jupyter is served from <mydomain>/jupyter

Actual behaviour

• <mydomain>/jupyter is a 404 served by traefik (my IngressController), indicating that traefik does not route that path to Jupyter.
• If I instead navigate to <mydomain>/jupyter/ with a trailing slash, it does route correctly and JH loads as expected.

The Ingress that gets created by helm looks like this:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    meta.helm.sh/release-name: jupyter
    meta.helm.sh/release-namespace: jupyter
  creationTimestamp: "2025-02-13T21:02:34Z"
  generation: 11
  labels:
    app: jupyterhub
    app.kubernetes.io/component: ingress
    app.kubernetes.io/instance: jupyter
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: jupyterhub
    chart: jupyterhub-4.1.0
    component: ingress
    helm.sh/chart: jupyterhub-4.1.0
    heritage: Helm
    release: jupyter
  name: jupyterhub
  namespace: jupyter
  resourceVersion: "2407046"
  uid: a3b6128c-bef4-4997-be30-b1c70320e876
spec:
  ingressClassName: traefik
  rules:
  - host: <mydomain>
    http:
      paths:
      - backend:
          service:
            name: proxy-public
            port:
              name: http
        path: /jupyter/
        pathType: Prefix

Note that the path is path: /jupyter/ with a trailing slash. That is because of line 20 in the ingress template:

- path: {{ $.Values.hub.baseUrl | trimSuffix "/" }}/{{ $.Values.ingress.pathSuffix }}

Since I have set hub.baseUrl but haven't set anything for ingress.pathSuffix, this has the effect of appending a slash to the value I set in hub.baseUrl. This prevents routing to the slash-free subpath.

If I patch the ingress with this file:

spec:
  ingressClassName: traefik
  rules:
  - host: <mydomain>
    http:
      paths:
      - backend:
          service:
            name: proxy-public
            port:
              name: http
        path: /jupyter
        pathType: Prefix

using the command

kubectl -n jupyter patch ingress jupyterhub --type strategic --patch-file jupyterhub-ingress.yaml

Then the Ingress path is set to /jupyter, and navigating to <mydomain>/jupyter works as expected.