systemd-nspawn: starting multiple shells

[Nikolaus@xxxxxxxx (Nikolaus Rath)]

On Jul 02 2018, Lennart Poettering <lennart at poettering.net> wrote:
>> Still not quite working, now there seems to be a problem with
>> /proc/self/fd in the new shell:
>> 
>> $ sudo systemd-nspawn -M $MACHINE \
>>      --private-users=1379532800:65536 --private-network \
>>      --as-pid2
[...]
>> 
>> What's happening here?
>
> the stdin/stdout/stderr fds of the nsenter process reference pipes
> that belong to the host side, and the kernel doesn't allow them to be
> reopened if user namespacing is used, for security reasons.
>
> "systemd-run -M $MACHINE -t /bin/sh" should generally be the better
> choice than "nsenter",

Yeah, but:

$ sudo systemd-run -M iofabric -t /bin/sh
[sudo] password for nikratio: 
Failed to create bus connection: No such file or directory

Does this maybe require a systemd instance running in the container? My
problem was that I can't run "machinectl shell" because the systemd
version in the container is too old..

Best,
-Nikolaus

-- 
GPG Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F

             »Time flies like an arrow, fruit flies like a Banana.«