How do I set an env var for systemd ExecStart command in Linux?

I've installed Snapclient on a raspi (a program which receives streaming music and plays it). It has a systemd service file which among others contains this line:

ExecStart=/usr/bin/snapclient --logsink=system $SNAPCLIENT_OPTS

I now want to set the $SNAPCLIENT_OPTS so I added the following line to /etc/environment:

SNAPCLIENT_OPTS="--host 192.168.178.79"

After a reboot and an ssh login as root I see that the env is set:

root@dietpi:~# env | grep SNAPCLIENT
SNAPCLIENT_OPTS=--host 192.168.178.79

However, the service still doesn't run with that argument:

root@dietpi:~# ps aux | grep snap
_snapcl+ 525 0.4 1.4 16632 7000 ? Ss 15:36 0:00 /usr/bin/snapclient --logsink=system

In the line above I do see that it isn't run as root though, but as the user _snapclient, which explains that the system wide env var isn't picked up. I guess I could set an env var for the user _snapclient, but that user doesn't even have a home directory. I can also change the systemd service file, but that seems like a hack.

What would be the correct way to set this env var and have it used when the snapclient service is started?

1 Answer

If snapclient.service works this way, it should also have an EnvironmentFile= setting that reads from /etc/default, /etc/conf.d, or some similar location. Put your environment variables there.

In case there's no EnvironmentFile specified, use systemctl edit to directly add Environment= directives to the service:

[Service]
Environment=SNAPCLIENT_OPTS="--host 192.168.178.79"