Creating a virtual ubuntu proxmox template

Install cloud-init sudo apt install cloud-init

Edit the /etc/cloud/cloud.cfg or use the one in this directory.

The cloud.cfg file in this directory have items removed.

snap,
byobu,
ubuntu-advantage,
disable-ec2-metadata,
fan,
landscape,
lxd,
puppet,
chef,
mcollective,
salt-minion,
rightscale-userdata,
reset_rmc,
refresh_rmc_and_interface

Inorder to make a template at least on ubuntu the contents of /etc/machine-id is used to assign ip adress instead of MAC id. Thus clear it out by e.g. sudo rm /etc/machine-id; sudo touch /etc/machine-id

Also check that /var/lib/dbus/machine-id is a link to /etc/machine-id. If it is not the create sudo rm /var/lib/dbus/machine-id sudo ln -s /etc/machine-id /var/lib/dbus/machine-id Clean apt and power off:

sudo apt clean
sudo poweroff

In the proxmox interface for machine in question. Select hardware and add a cloud-init disk. Then select Cloud-init and edit the field you must supply a user and password. The regenerate. Now the machine can be converted to a template, right click opn the machine.

Clone a new machine from the template and start the machine and test it e.g. check ip adress etc.