Just to synthesize, using unit-get is not totally deprecated to get the public IP. Depending on the cloud, like AWS, it won't be show into ingress-addresses. In the case of the layer-easyrsa it was not necessary to use the public address as the EasyRSA root certificate's common name.
The bottom line is the juju network model is currently insufficient for all use cases and charms should be resilient in case the IP is not ready independently which method is used.
Just to synthesize, using unit-get is not totally deprecated to get the public IP. Depending on the cloud, like AWS, it won't be show into ingress-addresses. In the case of the layer-easyrsa it was not necessary to use the public address as the EasyRSA root certificate's common name.
The bottom line is the juju network model is currently insufficient for all use cases and charms should be resilient in case the IP is not ready independently which method is used.