systemd/units/systemd-nspawn@.service.in

#  SPDX-License-Identifier: LGPL-2.1-or-later
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=Container %i
Documentation=man:systemd-nspawn(1)
Wants=modprobe@tun.service modprobe@loop.service modprobe@dm_mod.service
PartOf=machines.target
Before=machines.target
After=network.target modprobe@tun.service modprobe@loop.service modprobe@dm_mod.service
RequiresMountsFor=/var/lib/machines/%i

[Service]
# Make sure the DeviceAllow= lines below can properly resolve the 'block-loop' expression (and others)
ExecStart=systemd-nspawn --quiet --keep-unit --boot --link-journal=try-guest --network-veth -U --settings=override --machine=%i
KillMode=mixed
Type=notify
RestartForceExitStatus=133
SuccessExitStatus=133
Slice=machine.slice
Delegate=yes
DelegateSubgroup=supervisor
TasksMax=16384
{{SERVICE_WATCHDOG}}

{# Enforce a strict device policy, similar to the one nspawn configures when it
 # allocates its own scope unit. Make sure to keep these policies in sync if you
 # change them! #}
DevicePolicy=closed
DeviceAllow=/dev/net/tun rwm
DeviceAllow=char-pts rw

# nspawn itself needs access to /dev/loop-control and /dev/loop, to implement
# the --image= option. Add these here, too.
DeviceAllow=/dev/loop-control rw
DeviceAllow=block-loop rw
DeviceAllow=block-blkext rw

# nspawn can set up LUKS encrypted loopback files, in which case it needs
# access to /dev/mapper/control and the block devices /dev/mapper/*.
DeviceAllow=/dev/mapper/control rw
DeviceAllow=block-device-mapper rw

[Install]
WantedBy=machines.target