The setup involves two physical separated hosts:

• The 'main host', which needs to mount encrypted zfs datasets on boot and is expected to reboot from time to time.
• The 'provider host', which is solely used to save the password in memory. Regular reboots are not expected. A cheap single board computer like the raspberry pi is suitable for being the provider host.

When the main host boots, the password is retrieved via ssh from the provider host which stores the password in memory. The remote host can be a raspberry pi in your local network for example. In the rare case the provider host loses its memory because of a reboot, the password must be provided manually once. This can be done by executing ./provide_password.sh on the main host.

• Flash a fresh raspbian onto a sd card. I recommend using raspbian lite (without desktop) to limit the attack surface.
• Enable ssh on the rpi, disable password authentication and add your main host's public key to /root/.ssh/authorized_hosts
• I recommend giving the rpi a static ip address. In my example the rpi has the address '10.99.99.2'.

• Clone this project to some location on the host.
• Copy the automount.service to /etc/system/systemd/
• Edit the just created service file and:
  • replace the '/root/automount.sh' path to match the location of your automount.sh
  • edit the ip address to match your rpi's address
• Edit both automount.sh and provide_password.sh to use the correct ip address of your reaspberry pi.
• Edit automount.sh to contain the correct zfs paths of your encrypted datasets.
• Enable the automount service by executing systemctl enable automount && systemctl start automount.
• Manually execute ./provide_password.sh and type in your encryption password. It will be pushed to the memory of the rpi via ssh.'

Currently the automount.service is only tested on proxmox pve version 6. To make it work on other operating systems, slight modifications might be necessary. Make sure to modify the 'Before=' field to include all services which must wait for the encrypted datasets to be mounted before they start.