As of 04/2024 it looks like under Install OS > Custom > Debian 12 when you click change partitions you can select ZFS for boot and data
Ubuntu does not list ZFS in OVH WebGUI but you bring your own Linux This way OVH can install some of its management tools too (also configures IPv6)
OV BYOL requires a QCOW image (Quemu style container) Ubuntu calls these "Cloud images" and you download it from here to your local machine The default cloud image does not contain a file required by OVH that is for custom things only
In a local Ubuntu (or WSL)
downlaod image and go to directory https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64.img (618mb)
Ubuntu Jammy has guestmount already installed so you dont need this heavy package
sudo apt update sudo apt -y install libguestfs-tools
guestmount -a jammy-server-cloudimg-amd64.img -i /mnt/byol -a add image -i instpector = mount as if a real vm mounted
Add the bootstartup script as mentioned in OVH github - this is probably where you want to add ssh and set a user and password https://github.com/ovh/bringyourownlinux/
Then you just gotta host the file somewhwere so OVH can downlaod it.
With this gist the author leverages quemu to run an iso in the recovery instance to install to host instance.
With this you have full control so you need to know excatly what you doing with partitions, network setup, ssh, and including the zfs cli as you will be manually massaging in mirror disks (if you want - you can stripe them)
I tried this and got to the end but OVH panel was screaming at me with errors and also I didnt know how to get IPv6 to work. So I ended doing step 1, easy (Not Ubuntu but Debian is just as good)
https://gist.github.com/Vitawt-The-Duke/3bcf5eab48dfa4d8ca4866cd7be9826e
Found these tools while messing around with expert install which I will definately use going forward now any way
- WebBased Server Interface - https://cockpit-project.org/
- Cockpit ZFS Plugin - https://github.com/optimans/cockpit-zfs-manager