Per-rule transforms?

[aschereT]

I'd like to set transforms only for some rules and not all of them.

As far as I can tell, for the transforms annotation alb.ingress.kubernetes.io/transforms.${transforms-name}, the transforms-name must be the service name. Thus, the transform gets automatically applied to every listener rule.

Background: I want to set an ALB to listen to both service.example.com and example.com/apis/service. The subdomain is the existing URL, and we want to migrate to the path, but in the mean time we'd like to listen to both. For the subdomain, we should redirect to the path, then for the path we need to rewrite the path to strip the /service prefix (eg. /apis/service/foo to /foo).

I was able to configure this manually, but am stumped at the annotations.

I want something along the lines of

    alb.ingress.kubernetes.io/actions.fooservice-subdomain: >
      {"type":"redirect","redirectConfig":{"host":"example.com","path":"/apis/fooservice/#{path}","port":"443","protocol":"HTTPS","query":"#{query}","statusCode":"HTTP_301"}}
    alb.ingress.kubernetes.io/transforms.fooservice-path: >
      [
          {
              "type": "url-rewrite",
              "urlRewriteConfig": {
                  "rewrites": [
                      {
                          "regex": "^\\/apis\\/fooservice\\/(.+)$",
                          "replace": "/$1"
                      }
                  ]
              }
          }
      ]
  rules:
    - host: "example.com"
      http:
        paths:
          - path: /apis/fooservice/
            pathType: Prefix
            backend:
              service:
                name: fooservice
                port:
                  name: web
    - host: "fooservice.example.com"
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: fooservice
                port:
                  name: web

Am I missing something, or is it not possible?

[zac-nixon]

Can you use the Gateway API implementation for this? https://kubernetes-sigs.github.io/aws-load-balancer-controller/latest/guide/gateway/l7gateway/

Rule level settings don't really work in the Ingress API.

[aschereT]

Hmm I'll try it out. Thanks for the lead and prompt response!

[aschereT]

Hi, I ended up writing the transforms such that it does nothing on the non-applicable rule, so I didn't get around to trying out Gateway API.
Just an FYI for anyone looking this up.