Installing on debian Ubuntu

Installing from a source distribution or a Git repo checkout on debian-based distributions

Background Information

(You can skip directly to the following sections, if you are only interested in the "how" and not the "why".)

Debian-based systems fumble with the standard Python module search paths in a way, which leaves the standard way of installing Python modules broken - be it via autotools or, as in the case of jack_mixer, via meson.

These mentioned installation methods rely on the get_paths function from the sysconfig module of the Python standard library to return the correct installation paths for third-party modules. Even though debian / Ubuntu changes the Python module search path, sysconfig.get_path() returns the unchanged standard installation paths. A module, which is installed into one of these paths, will then not be importable (without manipulating sys.path manually) on debian / Ubuntu.

The following Python interactive session on Ubuntu 20.04 demonstrates the discrepancy between sys.path and sysconfig.get_paths() (some line-breaks added for better readability):

$ python3
Python 3.8.5 (default, Jul 28 2020, 12:59:40)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.path
['', '/usr/lib/python38.zip', '/usr/lib/python3.8', '/usr/lib/python3.8/lib-dynload',
 '/usr/local/lib/python3.8/dist-packages', '/usr/lib/python3/dist-packages']
>>> import sysconfig
>>> sysconfig.get_paths(scheme='posix_prefix')
{'stdlib': '/usr/lib/python3.8', 'platstdlib': '/usr/lib/python3.8', 
 'purelib': '/usr/lib/python3.8/site-packages', 'platlib': '/usr/lib/python3.8/site-packages', 
 'include': '/usr/include/python3.8', 'platinclude': '/usr/include/python3.8', 
 'scripts': '/usr/bin', 'data': '/usr'}

Ubuntu packagers say they don't support running software not installed via their package management, so they are not going to fix this.

This means, when we want to install jack_mixer ourselves manually from a source distribution or a Git repo checkout, we have to take some extra steps to adapt the jack_mixer start script to take the peculiarities of the Python module search paths on debian / Ubuntu into account.

This is not supported out-of-box in the vanilla jack_mixer sources, since we don't want to start catering to the vagaries of specific distributions. We'd rather have that meson on debian/Ubuntu is fixed to install Python modules to the directories the debian Python policy prescribes.

Ubuntu 20.04

Step 1: Install build and run-time requirements:

sudo apt-get install \
    build-essential \
    jackd2 \
    libglib2.0-dev \
    libjack-jackd2-dev \
    meson \
    pkgconf \
    python3-gi \
    python3-xdg

Step 2: Get the sources from the Git repo:

For this, we need some additional build dependencies:

sudo apt-get install cython3 git python3-docutils

Then clone the jack_mixer Git repository:

git clone https://github.com/jack-mixer/jack_mixer
cd jack_mixer

Step 2 (alternative): Get and unpack the source distribution:

wget https://rdio.space/jackmixer/tarballs/jack_mixer-15.tar.xz{,.sha256sum}
sha256sum -c jack_mixer-15.tar.xz.sha256sum && \
tar -xJf jack_mixer-15.tar.xz
cd jack_mixer-15

Step 3: Edit the jack_mixer start script to let it find the jack_mixer module:

sed -i -e \
  's|import sys$|import sys, sysconfig\nsys.path.insert(0, sysconfig.get_path("purelib"))|' \
  jack_mixer/__main__.py

Step 4: Then build and install jack_mixer:

meson setup builddir --prefix=/usr --buildtype=release
ninja -C builddir
sudo ninja -C builddir install

With meson versions >= 0.54.0 you can also use meson compile -C builddir and sudo meson install -C builddir instead, for the last two commands.

Ubuntu 18.04

Step 1: Install build and run-time requirements:

sudo apt-get install \
    build-essential \
    jackd2 \
    libglib2.0-dev \
    libjack-jackd2-dev \
    ninja-build \
    pkgconf \
    python-gi \
    python-xdg

Step 1a: The version of meson packaged for Ubuntu 18.04 (0.45.x) is too old to build jack_mixer, so we need to install meson >= 0.53.0 from PyPI under /usr/local:

sudo apt-get install python3-pip
sudo python3 -m pip install -U meson

Then continue with steps 2, 3 and 4 as described above for Ubuntu 20.04.