User services with `runit` on Void Linux

void linux howto

2019-11-23

Void Linux uses the very miminalsit service management tool runit. The runsvdir program monitors a folder for service definitions, and then supervises the processes described within. There is a system-wide instance of runsvdir for system services by default on Void, which is responsible for your ttys, sshd, maybe a logger, depending on your configuration.

There will be times when you want to run a service, or a set of services, as a user, rather than as root, and to do this you can use nested runsvdir.

Throughout these examples, replace 'voiduser' with your own username.

First, will define a system-wide service for running an instance of runsvdir for the user. This will find it's set of services in the folder $HOME/service:

$ sudo mkdir -p /etc/sv/voiduser
$ sudo touch /etc/sv/voiduser/run
$ sudo chmod +x /etc/sv/voiduser/run

Add the following to /etc/sv/voiduser/run:

#!/bin/sh

UID=$(pwd -P)
UID=${UID##*/}

if [ -d "/home/${UID}/service" ]; then
 chpst -u"${UID}" runsvdir /home/${UID}/service
fi

Now, start this service:

$ sudo ln -s /etc/sv/voiduser /var/service

Now, we create a service file for the user. In this example, it'll run syncthing, but you can adapt this for any given service:

$ mkdir -p $HOME/service/syncthing
$ touch $HOME/service/syncthing/run
$ chmod +x $HOME/service/syncthing/run

Then the contents of the run file:

#!/bin/sh

export HOME=/home/jonathan/
exec 2>&1
exec /usr/bin/syncthing

That's it. Now, your system-wide runit will start your user-level runit, and it'll run the service. You can check your process tree and see syncthing running as your own user.