I have deployed roon bridge (in a container) and in the “About” section it shows as connected:
However, when I navigate to the “Audio” menu, under the roon section, I get the below Device Not Found error - even though it clearly has found it because it has the name…
Additionally, if I restart the container it seems to work and then shows up as follows:
All looks good…but then when I try to play a track it gives me the following error message:
Any idea what would cause this kind of behaviour?
Not sure why you want to run it in a container, but that could be the issue: no permissions.
So it is being detected, but writing data to it is not allowed.
This is a guess of course 
The reason for running in a container is to use it with balenaSound - so I can manage the end nodes remotely and have them do other stuff than music when they are idle…this necessitates containerised usage.
However, it isn’t a permissions error as I get no permissions issues, it is running as root, and can access the soundcard directly from the container in an SSH tunnel.
A bit more detail - it seems like the device is locked by another service, although I am not entirely sure why - as nothing else is using it. But at least I am making progress…
More progress:
root@2ec9b5a:/opt/RoonBridge# speaker-test -c2 -t wav
speaker-test 1.1.8
Playback device is default
Stream parameters are 48000Hz, S16_LE, 2 channels
WAV file(s)
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 96 to 1048576
Period size range from 32 to 349526
Using max buffer size 1048576
Periods = 4
was set period_size = 262144
was set buffer_size = 1048576
0 - Front Left
1 - Front Right
But RoonBridge still seems to fail with Failed to open the audio device - so must be something in the alsa / pulse config I guess
Weirdly it is now working with the Pi onboard audio, but on the audio card it still says device not found…
