Bug#823322: please build "systemd-sysusers" binary

[Alban Crequy (Kinvolk)]

On Tue, May 17, 2016 at 2:34 AM, Michael Biebl <biebl at debian.org> wrote:
> Am 17.05.2016 um 02:26 schrieb Dmitry Smirnov:
>> On Sunday, 15 May 2016 2:01:20 PM AEST Michael Biebl wrote:
>>> Can you clarify a bit more, why exactly rkt needs systemd-sysusers?
>>
>> rkt uses systemd-sysusers inside containers therefore rkt build-depend on
>> systemd-sysusers...
>
> I was looking for more details what exactly it is needing
> systemd-sysusers for. Can you explain how the binary is called by rkt
> and when and what kind of users are created (and why)?

rkt with the "host" flavor does not build-depend on systemd-sysusers,
it is only a run-time dependency. It also only runs it in the
container to create users & groups in the container (not on the host).
It works like the following:

When rkt starts a pod / a container, it copies systemd-sysusers from
$PATH at run-time into rkt's stage1 rootfs:
https://github.com/coreos/rkt/blob/master/stage1/init/init.go#L168

systemd inside the pod uses the following service file to run the copy
of systemd-sysusers and create users & groups in the pod (not on the
host):
https://github.com/coreos/rkt/blob/master/stage1/units/units/sysusers.service

The code to generate the $ROOTFS/usr/lib/sysusers.d/ files is there:
https://github.com/coreos/rkt/blob/master/stage1/init/common/pod.go#L246