set an explicit ingress class name

[aogier]

This patch allows for specifying an explicit ingress class name, which is often needed in real-world prod clusters.

Thank you, regards

[timabbott]

Would it make sense to have a default value here, like "zulip"? I feel like probably that would be a reasonable default name for most deployments of this, but maybe I'm missing something about why someone would want something different, or potential breakage it could cause.

[aogier]

Hi, in this context the class name is basically a label I attach to a specific ingress controller instance, if eg. my k8s cluster is on multiple networks and I need to place an ingress on a specific network. In simpler (and very common) setups, it is common to have a single ingress controller and an empty classname would select this one if you mark it as default see manual:

❯ k get ingressclasses.networking.k8s.io nginx -o yaml
apiVersion: networking.k8s.io/v1
kind: IngressClass
metadata:
  annotations:
    ingressclass.kubernetes.io/is-default-class: "true"
  name: nginx
spec:
  controller: k8s.io/ingress-nginx

so a sane default could be to have it as an empty string, which produces the same design as the current chart, but one can configure it should a specific class is needed.
Take a random chart as an example: https://github.com/bitnami/charts/blob/main/bitnami/sonarqube/values.yaml#L611 (comment there is slightly misleading though)