Start Direwolf at Boot, the SystemD way

The ways to start Direwolf at boot, as provided in the manual, are quite archaic and hacky. Let’s see how we can do this in a more modern way using systemd.

Why I don’t like the solution provided in the manual

In the paragraph “5.9 Automatic Start Up After Reboot” the direwolf manual suggests using /etc/rc.local to start direwolf on boot. rc.local is an ancient way to do stuff on boot. However it has several drawbacks:

• You are not sure when it is called i.e. if all the system resources you need are already available
• AFAIK it has been deprecated since debian 9 (yet it is still working if you create it manually)
• No way to restart direwolf automatically if, for whatever reason, it fails

To address the latter problem the manual suggests to configure (dw-start.sh) a shell script as a cron job. Executing the script every minute. This will force direwolf to restart endlessly by banging the shell script every minute! But what if for some reason I really want to stop direwolf for a while? It’s impossible as the script will restart it right away… Not good…

Why it is better to do it using systemd?

• Start and stop direwolf whenever I want
• I can add other services which rely on direwolf and have them started after direwolf
• Automatically restart direwolf when it fails
• It is the way of doing such things on a modern Linux distro

Doing it the SystemD way

Using direwolf directly as a systemd (Type=simple) resulted in a strange effect: the service was never going out of the start phase, thus i decided to rely on tmux. Using tmux also brings the ability to observe what direwolf is doing at any moment, even with the fancy colored output!

Install tmux

sudo apt install tmux
Code language: Bash (bash)

Now we can create our systemd unit: create the following file /etc/systemd/system/direwolf.service

You have to adapt the command line to fit your own needs i.e. path to your config file

[Unit]
Description=Direwolf
After=network.target

[Service]
Type=forking
#Modify the end of the line below to fit your own needs i.e path to your configuration file
ExecStart=/usr/bin/tmux new-session -d -s direwolf '/usr/local/bin/direwolf -c /home/pi/direwolf.conf'
Restart=always

[Install]
WantedBy=default.target
Code language: Makefile (makefile)

Next step enable the service

sudo systemctl enable direwolf.service
Code language: Bash (bash)

If everything went OK you can now start the service using

sudo systemctl start direwolf.service
Code language: Bash (bash)

To stop it

sudo systemctl stop direwolf.service
Code language: Bash (bash)

Request its status

sudo systemctl status direwolf.service
Code language: CSS (css)

To attach to the tmux terminal in order to watch direwolf do its thing

sudo tmux attach -t direwolf

Conclusion

That’s it! We have direwolf running as a systemd service. There are a couple of things that could be improved though, but I leave them for later as I am so far happy wiht how it is working.

• Do not run as root user
• Templated systemd unit in order to specify the config file.