Storage nodes should implements Swift and Cinders

[TsutomuNakamura]

To be able to reduce physical nodes, storage nodes should implements features Swift and Cinders.

[TsutomuNakamura]

https://github.com/tsuna-server/build-server-ansible/blob/4dbd4156b868f8e216e7684e8334e495a6e6c2a8/roles/storage_common/tasks/format_volumes/format_volumes_for_each_nodes.yml#L2-L4

https://github.com/tsuna-server/build-server-ansible/blob/4dbd4156b868f8e216e7684e8334e495a6e6c2a8/roles/storage_common/tasks/format_volumes/format_volumes_for_each_nodes.yml#L10-L16

If storage nodes were declared in an inventory like below.

[storages]
dev-storage01
dev-storage02
dev-storage03

[default:children]
...
storages

The list group_names[0] might return a name of group default not storages. It does not has a guarantee of an order of declaration in an inventory.

TASK [storage_common : Debug group_names in storage_common] ******************************************************************
ok: [dev-storage01] => {
    "msg": "group_names => ['default', 'storages']"
}
ok: [dev-storage02] => {
    "msg": "group_names => ['default', 'storages']"
}
ok: [dev-storage03] => {
    "msg": "group_names => ['default', 'storages']"
}