Attempting to update an IPv6 subnet within Horizon that was created via CLI, and whose ipv6-address-mode is set (dhcp-stateful vs None), results in an error:
list index out of range
Creating the subnet via Horizon with the exact same parameters behaves properly.
--
Looking at the DB, I compared the CLI-created subnet to the Horizon-created subnet and found that Horizon sets the ipv6_ra_mode, too, which I suspect is the reason for the error:
+----------------------------------+--------------------------------------+----------------+--------------------------------------+------------+-------------------------+-----------------------+-------------+-----------------+-------------------+---------------+------------------+------------+--------+
| project_id | id | name | network_id | ip_version | cidr | gateway_ip | enable_dhcp | ipv6_ra_mode | ipv6_address_mode | subnetpool_id | standard_attr_id | segment_id | in_use |
+----------------------------------+--------------------------------------+----------------+--------------------------------------+------------+-------------------------+-----------------------+-------------+-----------------+-------------------+---------------+------------------+------------+--------+
| 78c44dffa72a44c58327088142091d12 | 828b3e14-307f-4d69-bd90-3f23e39b3c10 | IPV6-stateful | 57b47430-106d-489c-8219-388790d35db4 | 6 | 2001:4801:12a1:408::/64 | 2001:4801:12a1:408::1 | 1 | NULL | dhcpv6-stateful | NULL | 392 | NULL | 1 |
| 78c44dffa72a44c58327088142091d12 | a0aa908a-0c7f-4b7c-b53a-c21f997b5bbe | IPv6-horizon | 57b47430-106d-489c-8219-388790d35db4 | 6 | 6001:4801:12a1:408::/64 | 6001:4801:12a1:408::1 | 1 | dhcpv6-stateful | dhcpv6-stateful | NULL | 402 | NULL | 1 |
+----------------------------------+--------------------------------------+----------------+--------------------------------------+------------+-------------------------+-----------------------+-------------+-----------------+-------------------+---------------+------------------+------------+--------+
Looking at https://docs.openstack.org/neutron/latest/admin/config-ipv6.html, it makes sense why this would be the case. The CLI is a little too lax in that regard, since it appears to allow an invalid or unsupported configuration. Not sure if the error could be clearer. Thanks!
