[[setup-py]]
=== setup.py (Python3, CLI)

Here is an example of creating a simple Debian package from a Python3 CLI program using the *setup.py* as its build system.

Let's assume its upstream tarball to be *debhello-1.1.tar.gz*.

This type of source is meant to be installed as a non-system file as:

----
 $ tar -xzmf debhello-1.1.tar.gz
 $ cd debhello-1.1
 $ python3 setup.py install
----

Debian packaging requires to change the last line to ``*python3 setup.py install --install-layout=deb*'' to install files to the target system image location.  This issue is automatically addressed when using the *dh* command for the Debian packaging.

Let's get the source and make the Debian package.

.Download *debhello-1.1.tar.gz*
----
include::../debhello-1.1-pkg1/step000.slog[]
----

Here, the *hello* script and its associated *hello_py* module are as follows.

.*hello* (v=1.1)
----
include::../debhello-1.1-pkg1/step101.slog[]
----

.*hello_py/\_\_init__.py* (v=1.1)
----
include::../debhello-1.1-pkg1/step102.slog[]
----

These are packaged using the Python https://docs.python.org/3.4/library/distutils.html#module-distutils[distutils] with the *setup.py* and *MANIFEST.in* files.

.*setup.py* (v=1.1)
----
include::../debhello-1.1-pkg1/step103.slog[]
----

.*MANIFEST.in* (v=1.1)
----
include::../debhello-1.1-pkg1/step104.slog[]
----

TIP: Many modern Python packages are distributed using https://setuptools.pypa.io/en/latest/setuptools.html[setuptools].  Since setuptools is an enhanced alternative to distutils, this example is useful for them.

Let's package this with the *debmake* command.  Here, the *-b\':py3'* option is used to specify the generated binary package contain Python3 script and module files.

----
sys::[head -n12  ../debhello-1.1-pkg1/step200.slog]
...
----

Let's inspect notable template files generated.

.*debian/rules* (template file, v=1.1):
----
include::../debhello-1.1-pkg1/step202.slog[]
----

This is essentially the standard *debian/rules* file with the *dh* command.

The use of ``*--with python3*'' option invokes *dh_python3* to calculate Python dependencies, adds maintainer scripts to byte compile files, etc. See *dh_python3*(1).

The use of ``*--buildsystem=pybuild*'' option invokes various build systems for requested Python versions in order to build modules and extensions.  See *pybuild*(1).

.*debian/control* (template file, v=1.1):
----
include::../debhello-1.1-pkg1/step203.slog[]
----

Since this is the Python3 package, the *debmake* command sets ``*Architecture: all*'' and ``*Multi-Arch: foreign*''.  Also, it sets required *substvar* parameters as ``*Depends: $\{python3:Depends}, $\{misc:Depends}*''.  These are explained in <<basics>>.

Let's make this Debian package better as the maintainer.

.*debian/rules* (maintainer version, v=1.1):
----
include::../debhello-1.1-pkg1/step301.slog[]
----

.*debian/control* (maintainer version, v=1.1):
----
include::../debhello-1.1-pkg1/step302.slog[]
----

The *hello* command does not come with the upstream provided manpage, let's add it as the maintainer.

.*debian/manpages* etc. (maintainer version, v=1.1):
----
include::../debhello-1.1-pkg1/step303.slog[]
----

There are several other template files under the *debian/* directory.  These also needs to be updated.

The rest of the packaging activities are practically the same as the one in <<makefile-sh>>.

.Template files under *debian/*. (v=1.1):
----
include::../debhello-1.1-pkg1/step400.slog[]
----

Here is the generated dependency list of binary packages.

.The generated dependency list of binary packages (v=1.1):
----
include::../debhello-1.1-pkg1/step702.slog[]
----

