Comment 1 for bug 1989466

The reason this hasn't worked is because you've got the two sites in the same model and ingress is at the cluster level (i.e. outside of the model).

I think you want to use the ingress-proxy relation as documented on https://charmhub.io/content-cache-k8s:

juju deploy postgresql-k8s
juju deploy redis-k8s redis-cache
juju deploy redis-k8s redis-broker
juju deploy nginx-ingress-integrator
juju trust nginx-ingress-integrator --scope=cluster
juju deploy indico --config site_url=https://test.indico

juju relate redis-cache indico
juju relate redis-broker indico
juju relate indico postgresql-k8s:db
juju relate indico content-cache-k8s:ingress-proxy
juju relate nginx-ingress-integrator content-cache-k8s:ingress