Headless browser (chromium, gogole chrome): Failed to connect to socket /run/dbus/system_bus_socket

[malte-behrendt]

I'd like to run CI tests with a headless browser.

Minimal error message reproduction:
docker run -ti nixery.dev/shell/chromium chromium-browser --headless --no-sandbox

I get two errors:

• Fontconfig error: Cannot load default config file: No such file: (null). I guess it is the same as imagemagick commands dont work because of misconfigured fontconfig #134
• [1019/073412.146092:ERROR:bus.cc(392)] Failed to connect to the bus: Failed to connect to socket /run/dbus/system_bus_socket: No such file or directory

Failed resolution attempts:

• Adding a fontconfig file manually. Makes the error message go away, but second error remains and chromium is aborting
• Tried google-chrome instead
• Added other packages, like dbus, dependencies mentioned in chromium-browser source nix files

What am I missing? Do I need to start dbus somehow? Add a specific package?

I'm grateful for hints :-)