5. Creating Built Distributions
*******************************

A “built distribution” is what you’re probably used to thinking of
either as a “binary package” or an “installer” (depending on your
background).  It’s not necessarily binary, though, because it might
contain only Python source code and/or byte-code; and we don’t call it
a package, because that word is already spoken for in Python.  (And
“installer” is a term specific to the world of mainstream desktop
systems.)

A built distribution is how you make life as easy as possible for
installers of your module distribution: for users of RPM-based Linux
systems, it’s a binary RPM; for Windows users, it’s an executable
installer; for Debian-based Linux users, it’s a Debian package; and so
forth.  Obviously, no one person will be able to create built
distributions for every platform under the sun, so the Distutils are
designed to enable module developers to concentrate on their
specialty—writing code and creating source distributions—while an
intermediary species called *packagers* springs up to turn source
distributions into built distributions for as many platforms as there
are packagers.

Of course, the module developer could be their own packager; or the
packager could be a volunteer “out there” somewhere who has access to
a platform which the original developer does not; or it could be
software periodically grabbing new source distributions and turning
them into built distributions for as many platforms as the software
has access to.  Regardless of who they are, a packager uses the setup
script and the **bdist** command family to generate built
distributions.

As a simple example, if I run the following command in the Distutils
source tree:

   python setup.py bdist

then the Distutils builds my module distribution (the Distutils itself
in this case), does a “fake” installation (also in the "build"
directory), and creates the default type of built distribution for my
platform.  The default format for built distributions is a “dumb” tar
file on Unix, and a simple executable installer on Windows.  (That tar
file is considered “dumb” because it has to be unpacked in a specific
location to work.)

Thus, the above command on a Unix system creates
"Distutils-1.0.*plat*.tar.gz"; unpacking this tarball from the right
place installs the Distutils just as though you had downloaded the
source distribution and run "python setup.py install".  (The “right
place” is either the root of the filesystem or  Python’s "*prefix*"
directory, depending on the options given to the **bdist_dumb**
command; the default is to make dumb distributions relative to
"*prefix*".)

Obviously, for pure Python distributions, this isn’t any simpler than
just running "python setup.py install"—but for non-pure distributions,
which include extensions that would need to be compiled, it can mean
the difference between someone being able to use your extensions or
not.  And creating “smart” built distributions, such as an RPM package
or an executable installer for Windows, is far more convenient for
users even if your distribution doesn’t include any extensions.

The **bdist** command has a "--formats" option, similar to the
**sdist** command, which you can use to select the types of built
distribution to generate: for example,

   python setup.py bdist --format=zip

would, when run on a Unix system, create
"Distutils-1.0.*plat*.zip"—again, this archive would be unpacked from
the root directory to install the Distutils.

The available formats for built distributions are:

+---------------+--------------------------------+-----------+
| Format        | Description                    | Notes     |
|===============|================================|===========|
| "gztar"       | gzipped tar file (".tar.gz")   | (1)       |
+---------------+--------------------------------+-----------+
| "bztar"       | bzipped tar file (".tar.bz2")  |           |
+---------------+--------------------------------+-----------+
| "xztar"       | xzipped tar file (".tar.xz")   |           |
+---------------+--------------------------------+-----------+
| "ztar"        | compressed tar file (".tar.Z") | (3)       |
+---------------+--------------------------------+-----------+
| "tar"         | tar file (".tar")              |           |
+---------------+--------------------------------+-----------+
| "zip"         | zip file (".zip")              | (2),(4)   |
+---------------+--------------------------------+-----------+
| "rpm"         | RPM                            | (5)       |
+---------------+--------------------------------+-----------+
| "pkgtool"     | Solaris **pkgtool**            |           |
+---------------+--------------------------------+-----------+
| "sdux"        | HP-UX **swinstall**            |           |
+---------------+--------------------------------+-----------+
| "wininst"     | self-extracting ZIP file for   | (4)       |
|               | Windows                        |           |
+---------------+--------------------------------+-----------+
| "msi"         | Microsoft Installer.           |           |
+---------------+--------------------------------+-----------+

Changed in version 3.5: Added support for the "xztar" format.

Notes:

1. default on Unix

2. default on Windows

3. requires external **compress** utility.

4. requires either external **zip** utility or "zipfile" module
   (part of the standard Python library since Python 1.6)

5. requires external **rpm** utility, version 3.0.4 or better (use
   "rpm --version" to find out which version you have)

You don’t have to use the **bdist** command with the "--formats"
option; you can also use the command that directly implements the
format you’re interested in.  Some of these **bdist** “sub-commands”
actually generate several similar formats; for instance, the
**bdist_dumb** command generates all the “dumb” archive formats
("tar", "gztar", "bztar", "xztar", "ztar", and "zip"), and
**bdist_rpm** generates both binary and source RPMs.  The **bdist**
sub-commands, and the formats generated by each, are:

+----------------------------+---------------------------------------+
| Command                    | Formats                               |
|============================|=======================================|
| **bdist_dumb**             | tar, gztar, bztar, xztar, ztar, zip   |
+----------------------------+---------------------------------------+
| **bdist_rpm**              | rpm, srpm                             |
+----------------------------+---------------------------------------+
| **bdist_wininst**          | wininst                               |
+----------------------------+---------------------------------------+
| **bdist_msi**              | msi                                   |
+----------------------------+---------------------------------------+

The following sections give details on the individual **bdist_***
commands.


5.1. Creating RPM packages
==========================

The RPM format is used by many popular Linux distributions, including
Red Hat, SuSE, and Mandrake.  If one of these (or any of the other
RPM-based Linux distributions) is your usual environment, creating RPM
packages for other users of that same distribution is trivial.
Depending on the complexity of your module distribution and
differences between Linux distributions, you may also be able to
create RPMs that work on different RPM-based distributions.

The usual way to create an RPM of your module distribution is to run
the **bdist_rpm** command:

   python setup.py bdist_rpm

or the **bdist** command with the "--format" option:

   python setup.py bdist --formats=rpm

The former allows you to specify RPM-specific options; the latter
allows  you to easily specify multiple formats in one run.  If you
need to do both, you can explicitly specify multiple **bdist_***
commands and their options:

   python setup.py bdist_rpm --packager="John Doe <jdoe@example.org>" \
                   bdist_wininst --target-version="2.0"

Creating RPM packages is driven by a ".spec" file, much as using the
Distutils is driven by the setup script.  To make your life easier,
the **bdist_rpm** command normally creates a ".spec" file based on the
information you supply in the setup script, on the command line, and
in any Distutils configuration files.  Various options and sections in
the ".spec" file are derived from options in the setup script as
follows:

+--------------------------------------------+------------------------------------------------+
| RPM ".spec" file option or section         | Distutils setup script option                  |
|============================================|================================================|
| Name                                       | "name"                                         |
+--------------------------------------------+------------------------------------------------+
| Summary (in preamble)                      | "description"                                  |
+--------------------------------------------+------------------------------------------------+
| Version                                    | "version"                                      |
+--------------------------------------------+------------------------------------------------+
| Vendor                                     | "author" and "author_email", or  — &           |
|                                            | "maintainer" and "maintainer_email"            |
+--------------------------------------------+------------------------------------------------+
| Copyright                                  | "license"                                      |
+--------------------------------------------+------------------------------------------------+
| Url                                        | "url"                                          |
+--------------------------------------------+------------------------------------------------+
| %description (section)                     | "long_description"                             |
+--------------------------------------------+------------------------------------------------+

Additionally, there are many options in ".spec" files that don’t have
corresponding options in the setup script.  Most of these are handled
through options to the **bdist_rpm** command as follows:

+---------------------------------+-------------------------------+---------------------------+
| RPM ".spec" file option or      | **bdist_rpm** option          | default value             |
| section                         |                               |                           |
|=================================|===============================|===========================|
| Release                         | "release"                     | “1”                       |
+---------------------------------+-------------------------------+---------------------------+
| Group                           | "group"                       | “Development/Libraries”   |
+---------------------------------+-------------------------------+---------------------------+
| Vendor                          | "vendor"                      | (see above)               |
+---------------------------------+-------------------------------+---------------------------+
| Packager                        | "packager"                    | (none)                    |
+---------------------------------+-------------------------------+---------------------------+
| Provides                        | "provides"                    | (none)                    |
+---------------------------------+-------------------------------+---------------------------+
| Requires                        | "requires"                    | (none)                    |
+---------------------------------+-------------------------------+---------------------------+
| Conflicts                       | "conflicts"                   | (none)                    |
+---------------------------------+-------------------------------+---------------------------+
| Obsoletes                       | "obsoletes"                   | (none)                    |
+---------------------------------+-------------------------------+---------------------------+
| Distribution                    | "distribution_name"           | (none)                    |
+---------------------------------+-------------------------------+---------------------------+
| BuildRequires                   | "build_requires"              | (none)                    |
+---------------------------------+-------------------------------+---------------------------+
| Icon                            | "icon"                        | (none)                    |
+---------------------------------+-------------------------------+---------------------------+

Obviously, supplying even a few of these options on the command-line
would be tedious and error-prone, so it’s usually best to put them in
the setup configuration file, "setup.cfg"—see section Writing the
Setup Configuration File.  If you distribute or package many Python
module distributions, you might want to put options that apply to all
of them in your personal Distutils configuration file
("~/.pydistutils.cfg").  If you want to temporarily disable this file,
you can pass the "--no-user-cfg" option to "setup.py".

There are three steps to building a binary RPM package, all of which
are handled automatically by the Distutils:

1. create a ".spec" file, which describes the package (analogous
   to the Distutils setup script; in fact, much of the information in
   the setup script winds up in the ".spec" file)

2. create the source RPM

3. create the “binary” RPM (which may or may not contain binary
   code, depending on whether your module distribution contains Python
   extensions)

Normally, RPM bundles the last two steps together; when you use the
Distutils, all three steps are typically bundled together.

If you wish, you can separate these three steps.  You can use the "--
spec-only" option to make **bdist_rpm** just create the ".spec" file
and exit; in this case, the ".spec" file will be written to the
“distribution directory”—normally "dist/", but customizable with the "
--dist-dir" option.  (Normally, the ".spec" file winds up deep in the
“build tree,” in a temporary directory created by **bdist_rpm**.)


5.2. Creating Windows Installers
================================

Executable installers are the natural format for binary distributions
on Windows.  They display a nice graphical user interface, display
some information about the module distribution to be installed taken
from the metadata in the setup script, let the user select a few
options, and start or cancel the installation.

Since the metadata is taken from the setup script, creating Windows
installers is usually as easy as running:

   python setup.py bdist_wininst

or the **bdist** command with the "--formats" option:

   python setup.py bdist --formats=wininst

If you have a pure module distribution (only containing pure Python
modules and packages), the resulting installer will be version
independent and have a name like "foo-1.0.win32.exe". Note that
creating "wininst" binary distributions in only supported on Windows
systems.

If you have a non-pure distribution, the extensions can only be
created on a Windows platform, and will be Python version dependent.
The installer filename will reflect this and now has the form
"foo-1.0.win32-py2.0.exe".  You have to create a separate installer
for every Python version you want to support.

The installer will try to compile pure modules into *bytecode* after
installation on the target system in normal and optimizing mode.  If
you don’t want this to happen for some reason, you can run the
**bdist_wininst** command with the "--no-target-compile" and/or the "
--no-target-optimize" option.

By default the installer will display the cool “Python Powered” logo
when it is run, but you can also supply your own 152x261 bitmap which
must be a Windows ".bmp" file with the "--bitmap" option.

The installer will also display a large title on the desktop
background window when it is run, which is constructed from the name
of your distribution and the version number.  This can be changed to
another text by using the "--title" option.

The installer file will be written to the “distribution directory” —
normally "dist/", but customizable with the "--dist-dir" option.


5.3. Cross-compiling on Windows
===============================

Starting with Python 2.6, distutils is capable of cross-compiling
between Windows platforms.  In practice, this means that with the
correct tools installed, you can use a 32bit version of Windows to
create 64bit extensions and vice-versa.

To build for an alternate platform, specify the "--plat-name" option
to the build command.  Valid values are currently ‘win32’, and  ‘win-
amd64’. For example, on a 32bit version of Windows, you could execute:

   python setup.py build --plat-name=win-amd64

to build a 64bit version of your extension.  The Windows Installers
also support this option, so the command:

   python setup.py build --plat-name=win-amd64 bdist_wininst

would create a 64bit installation executable on your 32bit version of
Windows.

To cross-compile, you must download the Python source code and cross-
compile Python itself for the platform you are targeting - it is not
possible from a binary installation of Python (as the .lib etc file
for other platforms are not included.)  In practice, this means the
user of a 32 bit operating system will need to use Visual Studio 2008
to open the "PCbuild/PCbuild.sln" solution in the Python source tree
and build the “x64” configuration of the ‘pythoncore’ project before
cross-compiling extensions is possible.

Note that by default, Visual Studio 2008 does not install 64bit
compilers or tools.  You may need to reexecute the Visual Studio setup
process and select these tools (using Control Panel->[Add/Remove]
Programs is a convenient way to check or modify your existing
install.)


5.3.1. The Postinstallation script
----------------------------------

Starting with Python 2.3, a postinstallation script can be specified
with the "--install-script" option.  The basename of the script must
be specified, and the script filename must also be listed in the
scripts argument to the setup function.

This script will be run at installation time on the target system
after all the files have been copied, with "argv[1]" set to
"-install", and again at uninstallation time before the files are
removed with "argv[1]" set to "-remove".

The installation script runs embedded in the windows installer, every
output ("sys.stdout", "sys.stderr") is redirected into a buffer and
will be displayed in the GUI after the script has finished.

Some functions especially useful in this context are available as
additional built-in functions in the installation script.

directory_created(path)
file_created(path)

   These functions should be called when a directory or file is
   created by the postinstall script at installation time.  It will
   register *path* with the uninstaller, so that it will be removed
   when the distribution is uninstalled. To be safe, directories are
   only removed if they are empty.

get_special_folder_path(csidl_string)

   This function can be used to retrieve special folder locations on
   Windows like the Start Menu or the Desktop.  It returns the full
   path to the folder. *csidl_string* must be one of the following
   strings:

      "CSIDL_APPDATA"

      "CSIDL_COMMON_STARTMENU"
      "CSIDL_STARTMENU"

      "CSIDL_COMMON_DESKTOPDIRECTORY"
      "CSIDL_DESKTOPDIRECTORY"

      "CSIDL_COMMON_STARTUP"
      "CSIDL_STARTUP"

      "CSIDL_COMMON_PROGRAMS"
      "CSIDL_PROGRAMS"

      "CSIDL_FONTS"

   If the folder cannot be retrieved, "OSError" is raised.

   Which folders are available depends on the exact Windows version,
   and probably also the configuration.  For details refer to
   Microsoft’s documentation of the "SHGetSpecialFolderPath()"
   function.

create_shortcut(target, description, filename[, arguments[, workdir[, iconpath[, iconindex]]]])

   This function creates a shortcut. *target* is the path to the
   program to be started by the shortcut. *description* is the
   description of the shortcut. *filename* is the title of the
   shortcut that the user will see. *arguments* specifies the command
   line arguments, if any. *workdir* is the working directory for the
   program. *iconpath* is the file containing the icon for the
   shortcut, and *iconindex* is the index of the icon in the file
   *iconpath*.  Again, for details consult the Microsoft documentation
   for the "IShellLink" interface.


5.4. Vista User Access Control (UAC)
====================================

Starting with Python 2.6, bdist_wininst supports a "--user-access-
control" option.  The default is ‘none’ (meaning no UAC handling is
done), and other valid values are ‘auto’ (meaning prompt for UAC
elevation if Python was installed for all users) and ‘force’ (meaning
always prompt for elevation).
