How to connect DB from outside of DB LAN
External application (non-Juju)
Use case: the client application is a non-Juju application outside of Juju / DB LAN.
There are many possible ways to connect the Charmed PostgreSQL database from outside of the LAN the DB cluster is located. The available options are heavily depend on the cloud/hardware/virtualization in use. One of the possible options is to use virtual IP addresses (VIP) which the charm PgBouncer provides with assist of the charm/interface hacluster. Please follow the PgBouncer documentation for such configuration.
External relation (Juju)
Use case: the client application is a Juju application outside of DB deployment (e.g. hybrid Juju deployment with different VM clouds/controllers).
In this case the the cross-controllers-relation is necessary. Please contact Data team to discuss the possible option for your use case.