Hey,

So we have created an upgrade script, which will define variables neutron_plugin_type, neutron_ml2_drivers_type and neutron_plugin_base to their prior default values in case they are undefined to /etc/openstack_deploy/user_neutron_migration.yml file:
https://opendev.org/openstack/openstack-ansible/src/branch/unmaintained/zed/scripts/upgrade-utilities/define-neutron-plugin.yml

So based on your reply I would suggest adding the following explicitly:
neutron_ml2_drivers_type: "flat,vlan,vxlan,local"
neutron_plugin_type: ml2.lxb

While these missing variables should be handled by upgrade script, I'd still defined them explicitly.
Also I would suggest to double check that user_neutron_migration.yml was not created before things come to upgrading neutron.


On Fri, 28 Mar 2025, 15:16 Rambo Rambo, <ram.ramb2412@gmail.com> wrote:
Hi Team

We are planning openstack-ansible upgrade from Yoga to Zed.

Distribution:openstack-ansible
Release: Yoga
OS - Ubuntu 20.04

I was checking the release notes and can see below point related to neutron linux bridge.
We are having linux bridge at the moment.

===========================================================

  • With marking ML2/LinuxBridge driver as ‘Experimental’ in the upstream Neutron project OpenStack-Ansible has switched a default mechanism driver to ML2/OVN. In order to upgrade any existing deployment that was relying on defaults to the new OpenStack-Ansible version you must ensure that following variables are defined explicitly to ensure parity with existing functionality:

    neutron_plugin_type: ml2.lxb
neutron_ml2_drivers_type: "flat,vlan,vxlan,local"
neutron_plugin_base:
  - router
  - metering

    Failure to define any of these variables will result in playbook failures and neutron misconfiguration.

    We have covered this step with upgrade script that will create a user_neutron_migration.yml file with assumed defaults.

===================================================
As per above point we need to add new parameters into user_variables file .
also it is written "We have covered this step with upgrade script"


Current Configuration:
/etc/neutron/plugins/ml2# cat ml2_conf.ini
[ml2]
type_drivers = flat,vlan,vxlan,local
tenant_network_types = vxlan,flat
mechanism_drivers = linuxbridge,l2population
# ML2 flat networks
extension_drivers = port_security,subnet_dns_publish_fixed_ip

user_variable file only has below related parameters :

neutron_l2_population: true
neutron_plugin_base:
  - router
  - neutron_dynamic_routing.services.bgp.bgp_plugin.BgpPlugin

neutron_ml2_conf_ini_overrides:
  ml2:
     extension_drivers:
       - port_security
       - subnet_dns_publish_fixed_ip

Can someone please confirm what should be done to take care of above point of the release notes?

Regards