Bug#1004339: /usr/bin/systemctl: `systemctl start --user --wait` fails with "Failed to connect to bus: No such file or directory"

[Adam Dinwoodie]

Package: systemd
Version: 250.3-1
Severity: normal
File: /usr/bin/systemctl

Dear Maintainer,

According to the systemctl.1 man page, it should be possible to specify
`--wait` to systemctl commands that will start units, to have the
systemctl command block until the units terminate again. This seems to
work as expected for system units, but not for user units.

The attached short script provides a simple test case: given appropriate
ssh configuration, when run with `sudo bash test.sh` it will create a
new user called "test" with a simple example service template unit, then
log in through using ssh to start that unit twice, once without
`--wait`, and once with. Expected behaviour is for this script to
start both unit instances, with the second one sleeping before the
script finishes. Actual behaviour is that the first unit starts as
expected, but the second unit is never started, and the attempt gives a
return code of 1 and the following error printed to the terminal:

Failed to connect to bus: No such file or directory

As I say, the `--wait` function works as expected for system units; it's
only with user units that it seems to fail.

Kind regards,

Adam

-- Package-specific info:

-- System Information:
Debian Release: 11.2
APT prefers stable
APT policy: (990, 'stable'), (500, 'unstable'), (500, 'testing'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-10-cloud-amd64 (SMP w/2 CPU threads)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages systemd depends on:
ii adduser 3.118
ii libacl1 2.2.53-10
ii libapparmor1 2.13.6-10
ii libaudit1 1:3.0-2
ii libblkid1 2.36.1-8
ii libc6 2.33-3
ii libcap2 1:2.44-1
ii libcrypt1 1:4.4.18-4
ii libcryptsetup12 2:2.4.3-1
ii libfdisk1 2.36.1-8
ii libgcrypt20 1.9.4-5
ii libgnutls30 3.7.2-5
ii libgpg-error0 1.38-2
ii libip4tc2 1.8.7-1
ii libkmod2 28-1
ii liblz4-1 1.9.3-2
ii liblzma5 5.2.5-2
ii libmount1 2.36.1-8
ii libpam0g 1.4.0-9+deb11u1
ii libseccomp2 2.5.1-1+deb11u1
ii libselinux1 3.1-3
ii libsystemd0 250.3-1
ii libzstd1 1.4.8+dfsg-2.1
ii mount 2.36.1-8
ii util-linux 2.36.1-8

Versions of packages systemd recommends:
ii dbus [default-dbus-system-bus] 1.12.20-2
ii systemd-timesyncd [time-daemon] 250.3-1

Versions of packages systemd suggests:
ii libfido2-1 1.6.0-2
pn libtss2-esys-3.0.2-0 <none>
pn libtss2-mu0 <none>
pn libtss2-rc0 <none>
pn policykit-1 <none>
pn systemd-container <none>

Versions of packages systemd is related to:
pn dracut <none>
ii initramfs-tools 0.140
pn libnss-systemd <none>
ii libpam-systemd 250.3-1
ii udev 247.3-6

-- no debconf information

[Michael Biebl]

Control: tags -1 + moreinfo unreproducible

Am 25.01.22 um 13:13 schrieb Adam Dinwoodie:

>
> Failed to connect to bus: No such file or directory
>

Thanks for the reproducer.
I can't reproduce the issue with the instructions you provided (with
v250 from sid).

Your problem seems to be related to a missing dbus (user) bus in your
ssh session and the failing --wait is just a symptom.

Can you run busctl --user, systemctl --user status dbus.socket
dbus.service ?

Is dbus-user-session installed? Is libpam-systemd enabled?

[Adam Dinwoodie]

That was it: I'm running a fairly minimal headless system, and didn't
have dbus-user-session installed. After installing that package, my
reproduction script behaves as expected.

Mea culpa. Thank you for the help!