diskimage-builder/diskimage_builder/elements/dib-python
Ian Wienand 8662297517 Deprecate dib-python; remove from in-tree elements
We are at the point that all distributions we are building have Python
3, so any tools running in the chroot can assume Python 3 exists.
This makes dib-python redundant; mark it as deprecated and start to
remove it from elements where it is no longer required.

Change-Id: I5d852843ec65d3b04444b77c54c5b82424455cd8
2020-08-07 10:38:16 +10:00
..
cleanup.d Clean up dib-python symlink 2017-04-12 14:33:57 +10:00
environment.d Add support for CentOS 8 Stream 2020-06-22 10:36:30 +02:00
pre-install.d Add support for CentOS 8 Stream 2020-06-22 10:36:30 +02:00
README.rst Deprecate dib-python; remove from in-tree elements 2020-08-07 10:38:16 +10:00

==========
dib-python
==========

.. note::

   This element is deprecated.  All distributions support Python 3 so
   tools running in the chroot can simply use ``/usr/bin/python3``.

Adds a symlink to ``/usr/local/bin/dib-python`` which points at either a
``python2`` or ``python3`` executable as appropriate.

In-chroot scripts should use this as their interpreter
(``#!/usr/local/bin/dib-python``) to make scripts that are compatible
with both ``python2`` and ``python3``.  We can not assume
``/usr/bin/python`` exists, as some platforms have started shipping with
only Python 3.

``DIB_PYTHON`` will be exported as the python interpreter.  You should
use this instead of ``python script.py`` (e.g. ``${DIB_PYTHON}
script.py``).  Note you can also call ``/usr/local/bin/dib-python
script.py`` but in some circumstances, such as creating a ``virtualenv``,
it can create somewhat confusing references to ``dib-python`` that
remain in the built image.

This does not install a python if one does not exist, and instead fails.

This also exports a variable ``DIB_PYTHON_VERSION`` which will either be
'2' or '3' depending on the python version which dib-python points to.


.. note::

  The ``dib-python`` interpreter will be removed in ``cleanup.d``.  It
  is only intended for build scripts.