Use lib-common DownwardAPI to retrieve pod IP

[bshephar]

This change uses the lib-common env DownwardAPI [1] to write the pods IP to the env vars of the pod. We then retrieve this in local_settings.py to populate ALLOWED_HOSTS.

[1] https://github.com/openstack-k8s-operators/lib-common/blob/main/modules/common/env/env.go#L100-L114

Fixes #487
Jira: https://issues.redhat.com/browse/OSPRH-19216

[openshift-ci]

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[openshift-ci]

Hi @bshephar. Thanks for your PR.

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[bshephar]

@gibizer @fmount @stuggi Hey folks, happy New Year. Welcome to 2026.

Trying to solve a problem with IPV6 addresses raised by:
#478

I had initially proposed doing it this way:
#496

I know that @deshipu wasn't a huge fan of that implementation from the beginning. So, this is an attempt to find a compromise and still fix the problem of allowing Liveness/Readiness probes to healthcheck the individual pods.

What do y'all think of this alternative?

[bshephar]

Maybe we can avoid putting anything in local_settings.py using HTTPHeaders in the HTTPGetAction:
https://pkg.go.dev/k8s.io/api/core/v1#HTTPGetAction

That might be an even nicer approach actually - assuming that would actually work. Like, a request to the pod IP, but setting the Host HTTPHeader. Maybe Django would still block it, I'm not too sure. Just throwing theories and possible alternatives out there.

[stuggi]

Hi and Happy New Year!

If it works as intended, I'd prefer this implementation. its simple and easy.