For the 'User' case, user should first create an external/floating IP:

$#openstack floating ip create --subnet <ext-subnet-id> <ext-netowrk-id>
$ openstack floating ip create --subnet 48ddcfec-1b29-411b-be92-8329cc09fc12  3b4eb25e-e103-491f-a640-a6246d588561
+---------------------------+--------------------------------------+
| Field               | Value                                |
+---------------------+--------------------------------------+
| created_at          | 2017-10-02T09:22:37Z                 |
| description         |                                      |
| fixed_ip_address    | None                                 |
| floating_ip_address | 172.24.4.13                          |
| floating_network_id | 3b4eb25e-e103-491f-a640-a6246d588561 |
| id                  | 1157e2fd-de64-492d-b955-88ea203b4c37 |
| name                | 172.24.4.13                          |
| port_id             | None                                 |
| project_id          | 6556471f4f7b40e2bde1fc6e4aba0eef     |
| revision_number     | 0                                    |
| router_id           | None                                 |
| status              | DOWN                                 |
| updated_at          | 2017-10-02T09:22:37Z                 |
+---------------------+--------------------------------------+
and then create k8s service with type=LoadBalancer and load-balancer-ip=<floating_ip> (e.g: 172.24.4.13)

In both 'User' and 'Pool' methods, the extrenal IP address could be find in k8s service status information (under loadbalancer/ingress/ip)