[systemd-devel] How to run *ctl command using systemd-nspawn

[Koen Kooi]

Op 16 apr. 2013, om 20:14 heeft Zbigniew Jędrzejewski-Szmek <zbyszek at in.waw.pl> het volgende geschreven:

> On Tue, Apr 16, 2013 at 09:11:51AM +0200, Koen Kooi wrote:
>> Hi,
>> 
>> To help with flashing the onboard eMMC of a 100000 boards I'm using systemd-nspawn to run package postinstall scripts that generate UUIDs and some other things and it's working great for that! Every board now has a unique value in /etc/machine-id instead it being empty and systemd randomizing it on startup.
>> 
>> What doesn't work however is something like this:
>> 
>> 	systemd-nspawn -D ${PART2MOUNT} /usr/bin/timedatectl set-timezone Europe/Paris
>> 
>> or this:
>> 
>> 	systemd-nspawn -D ${PART2MOUNT} /usr/bin/hostnamectl set-hostname BeagleBoneBlack
>> 
>> I know I can run the lowlevel 'ln -sf <zoneinfo> /etc/timezone' or echo the name into /etc/hostname, but I'd like to use the *ctl commands because they work and have error handling built-in. 
>> it looks like I would need -b to get the *ctl commands to work, but -b doesn't support running single commands and exiting.
>> 
>> My goal is to be able to drop in a rootfs tarball and change timezone and hostname settings in a config file for the flasher script and avoid generating N different tarballs. For use in the office lab I use something like [1] to generate the hostnames based on board revision and serial number.
>> 
>> So, is there a way to *ctl command using systemd-nspawn in a rootfs that wasn't specially prepared (e.g. helper units/targets) for that?
> 
> With very recent systemd just run:
> 
> PID=$(head -n1 /sys/fs/cgroup/systemd/machine/$NAME/system/tasks)
> nsenter -m -u -i -n -p -t $PID /usr/bin/timedatectl set-timezone Europe/Paris
> ...
> nsenter -m -u -i -n -p -t $PID systemctl halt
> 
> where NAME is either speicified with -M or the name of the tree root.


I'll update my util-linux to get nsenter and give that a try, thanks!