Add neutron.yml to baremetal env

[claudia-lola]

Running kayobe overcloud service deploy to add baremetal mixin would get error:

TASK [kolla-ansible : Ensure the Kolla global configuration file exists] ************************************************************************
Friday 21 August 2026  07:18:43 +0000 (0:00:00.582)       0:00:07.127 *********                                                                 
[ERROR]: Task failed: Error rendering template: argument of type 'NoneType' is not iterable                                                     
                                                                                                                                                 
Task failed.                                                                                                                                     
Origin: /home/cloud-user/deployment/venvs/kayobe/share/kayobe/ansible/roles/kolla-ansible/tasks/config.yml:50:3                                 
                                                                                                                                                 
48   when: (kayobe_environment | default('')) | length > 0                                                                                       
49                                                                                                                                               
50 - name: Ensure the Kolla global configuration file exists                                                                                     
     ^ column 3
                                                                                                                                                 
<<< caused by >>>                                                                                                                                
                                                                                                                                                 
Error rendering template: argument of type 'NoneType' is not iterable                                                                            
Origin: <unknown>                                                                                                                                
                                                                                                                                                 
# yamllint disable-file --- ############################################################################# # [...]
                                    
fatal: [localhost]: FAILED! =>                                                                                                                   
    changed: false                                                                                                                               
    msg: 'Task failed: Error rendering template: argument of type ''NoneType'' is not
        iterable'

PLAY RECAP **************************************************************************************************************************************
controller0                : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
localhost                  : ok=7    changed=0    unreachable=0    failed=1    skipped=3    rescued=0    ignored=0  

Due to kolla_neutron_ml2_mechanism_drivers being undefined.

This PR adds defaults for kolla_neutron_ml2_mechanism_drivers in the baremetal env.

When added service deploy runs without error.

[coderabbitai]

Important

Review skipped

Auto incremental reviews are disabled on this repository.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Advanced

Run ID: dc0e1261-0786-4e5e-af79-6fb0a66a80f7

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

📝 Summary

Adds a baremetal Neutron configuration that sets kolla_neutron_ml2_mechanism_drivers to genericswitch and ovn. This prevents kayobe overcloud service deploy from failing with a NoneType template-rendering error.

Walkthrough

The bare-metal Neutron configuration now enables the genericswitch and ovn ML2 mechanism drivers.

Changes

Neutron configuration

Layer / File(s)	Summary
Configure ML2 mechanism drivers etc/kayobe/environments/baremetal/neutron.yml	Adds genericswitch and ovn to the Neutron ML2 mechanism driver configuration.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: 🟡 Moderate · up to 1b671

The new baremetal Neutron driver list places genericswitch before ovn, which can cause incorrect port-binding behavior. Reorder the drivers to place ovn before genericswitch before merging.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[coderabbitai]

Actionable comments posted: 1

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 66b454bc-9749-4330-b9c6-60961f36da87

📥 Commits

Reviewing files that changed from the base of the PR and between e9abece and 1b6710a.

📒 Files selected for processing (1)

• etc/kayobe/environments/baremetal/neutron.yml

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

📜 Review details

⏰ Context from checks skipped due to timeout. (5)

• GitHub Check: stackhpc/check
• GitHub Check: Ansible 2.19 lint with Python 3.12
• GitHub Check: Ansible 2.20 lint with Python 3.12
• GitHub Check: Tox docs with Python 3.12
• GitHub Check: Tox releasenotes with Python 3.12

🔇 Additional comments (1)

etc/kayobe/environments/baremetal/neutron.yml (1)

1-6: LGTM!

[mnasiadka]

I think my main problem with all this, is that management of such overrides currently in Kayobe brings in a lot of complications (as in we don't merge these lists between each other - just the last one wins).
I don't know if that should be a stopper, but numerous people have been spending additional time analysing why some values of lists are not getting populated correctly.

[oneswig]

Subject to the CodeRabbit comment about list ordering, and noting the wider discussion on why there wasn't a default, and how to work with multiple instantiations from different environments.