https://github.com/theasp/docker-novnc
https://stackoverflow.com/questions/43312975/record-sound-on-ubuntu-docker-image
apt-get update
apt-get install pulseaudio socat
apt-get install alsa-utils
# Start the pulseaudio server
pulseaudio -D --exit-idle-time=-1
# Load the virtual sink and set it as default
pacmd load-module module-virtual-sink sink_name=v1
pacmd set-default-sink v1
# set the monitor of v1 sink to be the default source
pacmd set-default-source v1.monitor Then use darkice and darksnow to send to icecast2. 
