Ingress should support frontend and backend via path based routing

[raffraffraff]

Problem: can't expost frontend and backend on different paths

The chart does not appear to support this because it's too prescriptive about what is allowed, ie: the host rule contains one port/path, and an extraHosts rule forces you to add another host which supports one port/path

  rules:
    - host: {{ include "common.tplvalues.render" ( dict "value" .Values.ingress.host "context" $ ) }}
      http:
        paths:
          - path: {{ .Values.ingress.path }}
            pathType: Prefix
            backend:
              service:
                name: {{ include "common.names.fullname" . }}
                port:
                  number: {{ .Values.service.ports.backend }}
    {{- range .Values.ingress.extraHosts }}
    - host: {{ .name | quote }}
      http:
        paths:
          - path: {{ default $.Values.ingress.path .path }}
            pathType: {{ default "Prefix" .pathType }}
            backend:
              service:
                name: {{ include "common.names.fullname" $ }}
                port:
                  number: {{ default $.Values.service.ports.backend .port }}

Use case

I'm deploying Backstage with Github OAuth authentication, which requires a callback address (that hits the backend). I don't want two different hosts, I want a single host with path based routing, eg:

• https://backstage.internal.company.com/frontend
• https://backstage.internal.company.com/backend

Suggestion

The template should have a more flexible approach to ingress configuration, allowing multiple path/port rules within a single host item. But instead of reinventing the wheel piecemeal, you could use the example from the NGNIX chart, which has support for flexible host/port/path combinations.