We have a medium size Openstack cluster deployed via Kolla-ansible. We need to make a patch to Nova to allow for a corner case on a few VMs running in this cluster.
Has anybody done this?
If so, do you have a guide on how to do it?
Ideally I would just like to patch the actual docker image for nova-compute, and not have to rebuild the entire kolla image collection (kolla-build).
Posted Nov 3, 2022, 2:25 PM UTC
u/psycocyst option is a good one, particularly if the modification can or should be applied to all nova-compute instances, and the change doesn't require variables on a per-host basis.
I understand the aversion to rebuilding all the kolla images, this alternative doesn't require touching kolla at all, instead all modifications could be made within kolla-ansible. Assuming you are already comfortable with Ansible, this could be a more flexible option.
There are quite some examples to work from already but the principle is for Ansible rather than openstack or kolla-ansible.
At a very high level the steps are:
Write a ansible playbook that modifies the nova-compute container as needed. Adding files example Be sure to also modify the relevant policy.json
Add a new subgroup in your inventory file, containing the hosts with the edge cases.
Incorporate your playbook into kolla-ansible Example
You can even use the --limit option as within kolla-ansible so that changes are applied only the required hosts.
Wow, I hadn't even considered this as a possible option. I was sort of fixated on the docker images being immutable, and hadn't even considered modifying them with Ansible after the fact.
Thanks for highlighting another avenue to pursue.
Look up template_ovwrride for Kolla. You can build individual container images or all for a project with kolla-build. I presume since you're in a decent sized deployment you're at least mirroring your local registry to local. Just replace the nova images with your own there.
Yeah. We are using harbor locally for our registry. I'll look into template_override as well.
kolla-ansible has a configuration file where you can override certain blocks of the docker file with your fixes/changes. can’t remember its name though.
Yes you can create a Dockerfile pointing to the image you want to modify and use standard dockerfile syntax to copy a file or run a command then push it up to your registry and update the image on the hosts with kolla pull and then reconfigure with limits.