Systemd user units fail to auto-start

Question

The unit file works when manually started. systemctl --user enable does not auto-start the service after user login.

Unit File

[Unit]
Description = VNC Duplicate Display RDP
After = default.target

[Service]
Type = simple
ExecStart = /opt/tigervnc/usr/bin/x0vncserver -passwordfile /etc/.vncpasswd -display :0
TimeoutSec = 30
RestartSec = 10
Restart = always

[Install]
WantedBy = default.target

I have reloaded and reenabled this unit

$ systemctl --user daemon-reload
$ systemctl --user reenable x0vncserver

Status

Status after user login

● x0vncserver.service - VNC Duplicate Display RDP
   Loaded: loaded (/usr/lib/systemd/user/x0vncserver.service; enabled; vendor preset: enabled)
   Active: inactive (dead)

Target Status

$ systemctl --user --type target
UNIT           LOAD   ACTIVE SUB    DESCRIPTION
basic.target   loaded active active Basic System
default.target loaded active active Default
paths.target   loaded active active Paths
sockets.target loaded active active Sockets
timers.target  loaded active active Timers

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

5 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.

Manual Start

$ systemctl --user start x0vncserver
$ systemctl --user status x0vncserver
● x0vncserver.service - VNC Duplicate Display RDP
   Loaded: loaded (/usr/lib/systemd/user/x0vncserver.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2017-08-07 18:27:00 IST; 5s ago
 Main PID: 2999 (x0vncserver)
   CGroup: /user.slice/user-1004.slice/[email protected]/x0vncserver.service
           └─2999 /opt/tigervnc/usr/bin/x0vncserver -passwordfile /etc/.vncpasswd -display :0

Aug 07 18:27:00 Machine systemd[930]: Started VNC Duplicate Display RDP.
Aug 07 18:27:00 Machine x0vncserver[2999]: Mon Aug  7 18:27:00 2017
Aug 07 18:27:00 Machine x0vncserver[2999]:  Geometry:    Desktop geometry is set to 1920x1080+0+0
Aug 07 18:27:00 Machine x0vncserver[2999]:  Main:        XTest extension present - version 2.2
Aug 07 18:27:00 Machine x0vncserver[2999]:  Main:        Listening on port 5900

References

I've looked around and found users with similar issues but none of the proposed solutions fixed my issue

• https://stackoverflow.com/questions/39871883/systemctl-status-shows-inactive-dead
• https://bbs.archlinux.org/viewtopic.php?id=170344
• Why is my Systemd unit loaded, but inactive (dead)?
• https://github.com/systemd/systemd/issues/4301
• https://github.com/systemd/systemd/issues/2690
• https://superuser.com/questions/955922/enabled-systemd-unit-does-not-start-at-boot

Update

This happens to a particular user. systemctl --user enable works for at least one other user on the same device.

Answer 1

I had the same problem, what fixed it for me was using it as follows:

#!/bin/bash
/usr/bin/x0vncserver -PasswordFile=/home/luserid/.vnc/passwd -display=:0

it seems it won't start right without the -display=:0.

Answer 2

To let systemd run a VNC server, that server needs two things:

1. $DISPLAY
2. $XAUTHORITY

If you are running on the user-bus (which you are), these are often set automatically. I've found that when these variables are reliably set, I don't need to be explicit with --display which is good because it can change based on my configuration. Tigervnc might be different, but I would expect it to use $DISPLAY if --display isn't specified.

So how do you ensure these are reliably set when you start your service?

These may not be set immediately if your user logs in before the X-server is fully up and running. I find this happens on systems where I use auto-login from GDM, or if I log in via SSH or a TTY before logging in via display-manager.

The solution I use on my Debian system is to only run my vnc server after Xauthority is guaranteed to be available. I detect that with a *.path unit:

# ~/.config/systemd/user/vnc.path
[Path]
PathExists=%t/gdm/Xauthority

[Install]
WantedBy=default.target

# ~/.config/systemd/user/vnc.service
[Service]
ExecStart=x11vnc -shared -many -nopw

You only need to systemctl --user enable vnc.path for this to work.

The path unit will sit and wait for /run/user/1000/gdm/Xauthority to exist. That will only exist AFTER your user has access to a display. When it is created, the path unit will start vnc.service and your VNC server will start with $DISPLAY and $XAUTHORITY variables set automatically.

The path %t/gdm/Xauthority is a default path on Debian. %t is short for /run/user/1000 and I like using that short-hand because it works if your UID is not 1000. Take a look at echo $XAUTHORITY if you need a different path if you're on a different distro.

---

Side-note:

The systemd design has some targets of interest. default.target is meant to be symlinked to graphical.target which has some relationships with graphical-session.target which is implemented the desktop environment (e.g. gnome-session.target).

Theoretically, using WantedBy=graphical-session.target and After=graphical-session.target is a simpler and better solution to the *.path I mentioned, but unfortunately the implementation needs to be done by the desktop-environments, and that does not appear to have happened yet on all DEs. I've found that graphical-session.target isn't raised on all desktop environments reliably, hence the *.path solution is my recommendation.