Add an option to specify a common default VIM key across Tacker nodes.
To enable this, a new `default_secret_key` parameter will be added
under `[vim_keys]` in `tacker.conf`.
Administrators will generate a default Fernet key file in advance
(e.g., `default.key`), place it in the existing `openstack` directory
(default: `/etc/tacker/vim/fernet_keys`) on each Tacker node, and
specify the filename using the `default_secret_key` option.
Implements: blueprint vim-key-for-multi-master
Change-Id: Id3c736ef27eb51bca2d4a136eda4af121bce9391
Signed-off-by: Hitomi Koba <hi-koba@kddi.com>
5bcc805b6f