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Distributing Python Modules |  |
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Distributing Python Modules | |
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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 Windows world. ** do Mac people use it? **)
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 of packager springs up to turn source distributions into built distributions for as many platforms as there are packagers.
Of course, the module developer could be his 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 the nature of the beast, 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 an 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-0.9.1.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 a huge win--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 a big win 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-0.8.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 |
|---|---|---|
| gzipped tar file (.tar.gz) | (1),(3) | |
| compressed tar file (.tar.Z) | (3) | |
| tar file (.tar) | (3) | |
| zip file (.zip) | (4) | |
| RPM | (5) | |
| source RPM | (5) ** to do! ** | |
| self-extracting ZIP file for Windows | (2),(4) |
Notes:
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, ztar, gztar, and
zip), and bdist_rpm generates both binary and source
RPMs. The bdist sub-commands, and the formats generated by
each, are:
| Command | Formats |
|---|---|
| tar, ztar, gztar, zip | |
| rpm, srpm | |
| wininst |
The following sections give details on the individual bdist_*
commands.
** Need to document absolute vs. prefix-relative packages here, but first I have to implement it! **
The RPM format is used by many of 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@python.net>" \
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 | licence |
| Url | url |
| %description (section) | long_description |
Additionally, there 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 section | bdist_rpm option |
default value |
|---|---|---|
| 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) |
There are three steps to building a binary RPM package, all of which are handled automatically by the Distutils:
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.)
** this isn't implemented yet--is it needed?! ** You can also specify a custom .spec file with the --spec-file option; used in conjunction with --spec-only, this gives you an opportunity to customize the .spec file manually:
> python setup.py bdist_rpm --spec-only # ...edit dist/FooBar-1.0.spec > python setup.py bdist_rpm --spec-file=dist/FooBar-1.0.spec
(Although a better way to do this is probably to override the standard
bdist_rpm command with one that writes whatever else you want
to the .spec file; see section
Executable Windows installers are the natural format for binary distributions on Windows. They display a nice GUI interface, display some information of the module distribution to be installed, taken from the meta-dada in the setup script, let the user select a few (currently maybe too few) options, and start or cancel the installation.
Since the meta-data 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 --format 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. These installers can even be created on Unix or MacOS platforms.
If you have a non-pure distribution, the extensions can only be created on a Windows platform, and will be Python version dependend. 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.
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Distributing Python Modules | |
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