I found the answer here: https://askubuntu.com/questions/196444/how-do-i-auto-start-xen-guests-on-boot/906499#906499
The Short Answer
To load all config files on boot link the
auto folder directly to
ln -s /etc/xen/ /etc/xen/auto
To load only specific config files link each individually:
mkdir -p /etc/xen/auto
ln -s /etc/xen/MY_DOMU_GUEST_1.cfg /etc/xen/auto/
ln -s /etc/xen/MY_DOMU_GUEST_2.cfg /etc/xen/auto/
There's a lesser-known
xen config file
There you can find in the comments documentation for three default settings:
To summarize the docs:
XENDOMAINS_SAVE causes the VMs to be saved on a proper
XENDOMAINS_RESTORE causes the VMs to be brought back up from the saved state when saved (whether saved manually with
xl save or due to host reboot).
XENDOMAINS_AUTO specifies a folder from which to load configs for VMs when no save state exists (i.e.
XENDOMAINS_SAVE is disabled or there was a power failure or explicit
shutdown instead of a
If you create the
auto folder under
/etc/xen and give it symlinks to the config file of the virtual machine (DomU guest) you'd like to start on physical machine (Dom0 host) then generally speaking they'll restore from the saved state that happens during the physical (host) server on reboot, but when that isn't available (such as after a shutdown or power failure or crash), they'll still load anyway.
If you'd rather always have the VMs shutdown on reboot rather than save state you can set
The Old Way
It used to be that where there is now
on_crash that you could also configure
on_xend_start = 'start' and
on_xend_stop = 'shutdown'... but those are not the current practice.
Current (apply to the VM state itself):
on_shutdown = 'destroy'
on_reboot = 'restart'
on_crash = 'restart'
Ignored / Deprecated (apply to the host state):
on_xend_start = 'start'
on_xend_stop = 'shutdown'