Proxmox VE 6.x release includes a feature to add custom cloud-init configs. Unfortunately there is poor documentation, so I had to figure this out by adding pieces of information together.

The custom cloud-init files (user-data, meta-data, network-config)

The cloud-init files need to be stored in a snippet. This is not very well documented:

1. Go to Storage View -> Storage -> Add -> Directory
2. Give it an ID such as snippets, and specify any path on your host such as /snippets
3. Under Content choose Snippets and de-select Disk image (optional)
4. Upload (scp/rsync/whatever) your user-data, meta-data, network-config files to your proxmox server in /snippets/snippets/ (the directory should be there if you followed steps 1-3)

Finally, you just need to qm set with --cicustom, like this:

qm set 100 --cicustom "user=snippets:snippets/user-data,network=snippets:snippets/network-config,meta=snippets:snippets/meta-data"

Replace 100 with the ID of your VM.

Add CloudInit Drive

Your VM needs a CloudInit Drive as well, since Proxmox adds your cloud-init data from your snippets into that drive (/dev/sr0 ?). Leave the Cloud-Init UI settings to default, since they won't be used anyways.

Warning

For the moment, you can not put the user-data, meta-data, network-config in any subdirectories, so something like this will fail:

qm set 100 --cicustom "user=snippets:snippets/cloud/data/user-data,network=snippets:snippets/cloud/data/network-config,meta=snippets:snippets/cloud/data/meta-data"

Finally, to apply the new cloud-init config you'll need to power off/on the server (not reboot).

Once booted

Once booted, your platform/datasource will be seen as nocloud and not OpenStack... assuming you're familiar with cloud-init, everything else should work perfectly.

Hope this helps someone out there!