If you just got a chance to go through the proxmox templating episodes and found yourself wondering what else can I do with cloud-init…
Cloud-init works just fine with LXC containers. The proxmox GUI does not let you attach cloud-init drives but, other data sources work. ie. Anything you set in the cloud.cfg file will apply on the next reboot.
You can set up a local HTTP server to act as a data source. Basically, you add a
seedfrom: http://ip_address:port/to your cloud.cfg.