Floating IPs

A floating IP is an IP address whose lifecycle is decoupled from that of the VM it is associated with.
This makes it possible to pre-declare a stable public IP in DNS and attach it to the dynamic private IP of a VM at deployment time.

https://registry.terraform.io/providers/terraform-provider-openstack/openstack/latest/docs/data-sources/networking_network_v2

data openstack_networking_network_v2 public {
    name = var.PUBLIC_NETWORK_NAME
}

https://registry.terraform.io/providers/terraform-provider-openstack/openstack/latest/docs/data-sources/networking_subnet_ids_v2

data openstack_networking_subnet_ids_v2 public_subnet_ids {
    network_id = data.openstack_networking_network_v2.public.id
}

https://registry.terraform.io/providers/terraform-provider-openstack/openstack/latest/docs/resources/networking_floatingip_v2

resource openstack_networking_floatingip_v2 fip_instance1 {
  description = format("fip.instance1.%s", var.CLOUD_PROJECT_DOMAIN_NAME)
  pool        = data.openstack_networking_network_v2.public.name
  subnet_ids  = data.openstack_networking_subnet_ids_v2.public_subnet_ids.ids
  tags        = []
}
resource openstack_networking_floatingip_v2 fip_instance2 {
  description = format("fip.instance2.%s", var.CLOUD_PROJECT_DOMAIN_NAME)
  pool        = data.openstack_networking_network_v2.public.name
  subnet_ids  = data.openstack_networking_subnet_ids_v2.public_subnet_ids.ids
  tags        = []
}

Persistent Volumes Load Balancers