How to connect to pulseaudio server from service

MemoNick

3/10/24, 6:09 PM

I'm developing a simple app to duck audio automatically using the pulsectl-asyncio library. I've developed the application in Python with a virtual environment, and when I run the script from the command-line, it works fine: /path/to/venv/bin/python /path/to/main.py.

The problem is running it as a service. When I run the script as a service, I get an error: pulsectl.pulsectl.PulseError: Failed to connect to pulseaudio server. The following is my service configuration:

[Unit]
Description=Auto-ducker
After=multi-user.target
[Service]
Type=simple
Restart=always
User=myuser
Group=myuser
ExecStart=/path/to/venv/bin/python /path/to/main.py
[Install]
WantedBy=multi-user.target

I get the same error when I run the script as myself through sudo: sudo -H -u myuser bash -c '/path/to/venv/bin/python /path/to/main.py'.

Why does the script run from the command-line but not as a service? And how can I run the script as a service?

1 + 3

pulseaudio

services

Matias N Goldberg

3/10/24, 6:14 PM

Most PulseAudio apps need a working xorg session environment (or Wayland, + dbus, etc). This is sent through environment variables. I don't know if it's possible, but if so, you need to tell systemd to inherit the necessary env variables from myuser's graphical interface

Matias N Goldberg

3/10/24, 6:16 PM

If you type `env` in the console you can see all the environment variables set for that console. Start removing them until your app stops working to narrow down which ones you need

MemoNick

3/10/24, 6:35 PM

@MatiasNGoldberg Thank you, that worked!

Score:0

Ubuntu

MemoNick

3/10/24, 6:34 PM

As Matias commented, the solution was to find the missing environment variables. In my case, it was XDG_RUNTIME_DIR=/run/user/1000.

My final service looks like this:

[Unit]
Description=Auto-ducker
After=multi-user.target
[Service]
Environment=XDG_RUNTIME_DIR=/run/user/1000
Type=simple
Restart=always
User=nicholas
Group=nicholas
ExecStart=/path/to/venv/bin/python /path/to/main.py
[Install]
WantedBy=multi-user.target

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