Vagrantfile to set up Ubuntu disco with ALSA

Vagrantfile

    # -*- mode: ruby -*-
  # vi: set ft=ruby :

  # This is `Vagrantfile.make`.  It specifies the provisioning and
  # configuration of the base Perkify VM (before add_ons is run).
  #
  # The ALSA-specific code is adapted from Christoph Neumann's vagrant-audio
  # Vagrantfile (in https://github.com/christoph-neumann/vagrant-audio), with
  # help from Clemens Ladisch and Eric Zuck.

  Vagrant.configure("2") do |config|
    config.ssh.forward_x11  = true

    vm              = config.vm
    vm.box          = "bento/ubuntu-19.04"
    vm.box_version  = "201906.18.0"

    # Create a forwarded port mapping which allows access to a specific port
    # within the machine from a port on the host machine and only allow access
    # via 127.0.0.1 to disable public access.

    vm.network 'forwarded_port',
      guest:    80,
      host:     8080,
      host_ip:  '127.0.0.1'

    vm.provision :shell, inline: <<-SHELL
      set -ex
      hostname perkify-make
      apt-get update

      # Provision ALSA.

      extra=linux-modules-extra-$(uname -r)
      echo "extra: $extra" #!T
      apt-get install -y linux-image-generic $extra alsa-utils

      sudo usermod -aG audio vagrant
      text='pcm.!default {\n  type plug\n  slave.pcm "hw:0,1"\n}'
      echo -e $text | tee >/dev/null /etc/asound.conf
      sudo modprobe snd
      sudo modprobe snd-hda-intel
      sleep 2
      sudo amixer -c 0 set Master playback 100% unmute

      echo 'finis'
    SHELL

    # Customize ALSA.

    config.vm.provider :virtualbox do |vb|
      audio = case RUBY_PLATFORM
        when /darwin|mac os/;                             'coreaudio'
        when /mswin|msys|mingw|cygwin|bccwin|wince|emc/;  'dsound'
        when /linux/;                                     'alsa'
      end

      vb.customize [ 'modifyvm',  :id,
        '--audio',                audio,
        '--audiocontroller',      'hda',
        '--audioout',             'on'
      ]
    end

  end