host2regex: doesn't take in consideration *

[MustafaSaber]

converting host from Ingress/RouteGroup for Host predicate doesn't take into consideration that Ingress support wildcard hostnames (see https://kubernetes.io/docs/concepts/services-networking/ingress/#hostname-wildcards) and we produce invalid regex

This PR adds testcases to reproduce the error, requires fix before merging.

following ingress produce

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: simple
  labels:
    name: simple
spec:
  rules:
  - host: "*.example.org"
    http:
      paths:
      - pathType: Prefix
        path: "/"
        backend:
          service:
            name: simple
            port: 
              number: 80

Error:

[APP]time="2024-11-01T12:43:46Z" level=error msg="kube_default__simple_redirect_app_default_0____example_org_____ [2]: error parsing regexp: missing argument to repetition operator: *

fixes #3297

[MustafaSaber]

maybe it's not a good idea to have this at all

[MustafaSaber]

another idea is to update validation webhook to say if the host regex is valid

[szuecs]

I think you want
^([a-z0-9][a-z0-9-]*)?[.]example....

Better also to write down in the issue what kind of match or regexp you want to create.

[MustafaSaber]

I want to match a valid hostname, it can't end or start with - I think this ([a-z0-9][a-z0-9-]*) can end with -

[szuecs]

What about foo-bar-qux.example , that your regexp doesn't match?

maybe:

^[a-z0-9]([a-z0-9-]*[a-z0-9])?[.]example....

Not sure if we need the capture group for the full first part of the hostname.

[MustafaSaber]

updated the PR to match it, the new regex [a-z0-9]+((-[a-z0-9]+)?)*

[MustafaSaber]

See #3297 (comment)

[MustafaSaber]

@szuecs

A problem with the current implementation is that a request can flap between 2 or more routes

request to foo.example with

r: Host("*.example") -> <shunt>;
s: Host("foo.example") -> <shunt>;

[AlexanderYastrebov]

We need to verify this matches behaviour descibed at https://kubernetes.io/docs/concepts/services-networking/ingress/#hostname-wildcards

Makes sense to add this link as a comment.

Subdomain regexp looks strange with two capture groups using ? followed by *.

I guess subdomain shoud start and end with alphanumeric (not dash). Lets check this https://stackoverflow.com/questions/7930751/regexp-for-subdomain and similar answers and reuse/adopt regexp from there.

[szuecs]

Sounds like #3296 (comment) would be the one 😀
Limiting the size makes also sense as you linked and non ascii domain support is also great to have!