Unable to use Load Balancer's IP address for the ingress gateway

[Gmerold]

Bug Description

New version of pydantic-core breaks falling back to the Load Balancer's IP for the ingress gateway when the external-hostname is not configured:

pydantic_core._pydantic_core.ValidationError: 1 validation error for IngressProviderAppData
ingress.url
  Input should be a valid URL, invalid IPv4 address [type=url_parsing, input_value='http://sdcore-nms.10.0.0.2/', input_type=str]
    For further information visit https://errors.pydantic.dev/2.6/v/url_parsing

Potential solution here could be using nip.io to pretend LB IP is a legit URL (e.g. 10.0.0.2.nip.io)

To Reproduce

https://canonical-charmed-aether-sd-core.readthedocs-hosted.com/en/stable/tutorials/getting_started/

Environment

Juju 3.4
Microk8s 1.27-strict/stable
Traefik latest/stable

Relevant log output

pydantic_core._pydantic_core.ValidationError: 1 validation error for IngressProviderAppData
ingress.url
  Input should be a valid URL, invalid IPv4 address [type=url_parsing, input_value='http://sdcore-nms.10.0.0.2/', input_type=str]
    For further information visit https://errors.pydantic.dev/2.6/v/url_parsing

Additional context

No response

[PietroPasotti]

We think the issue is that the url being submitted to traefik is wrong because it is in fact not a valid ipv4 address: http://sdcore-nms.10.0.0.2/
pydantic deduces it's ipv4 because it ends in digits.

Is it an option to turn the address around and let it be http://10.0.0.2.sdcore-nms/ instead, which would be a valid DNS record?

[Gmerold]

I agree with your thinking ;)
That's why I proposed using nip.io. It turns the IP into a valid URL, eliminates a need of adding entries to /etc/hosts and makes the URL feel natural (unlike http://10.0.0.2.sdcore-nms/, which kinda reverses the natural order, don't you think?).