a6bba674a2
[Peter: fix s/BUILD_TYPE/SETUP_TYPE/ typo in manual as noted by Samuel] Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
160 lines
6.5 KiB
Plaintext
160 lines
6.5 KiB
Plaintext
// -*- mode:doc; -*-
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// vim: set syntax=asciidoc:
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Infrastructure for Python packages
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This infrastructure applies to Python packages that use the standard
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Python setuptools mechanism as their build system, generally
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recognizable by the usage of a +setup.py+ script.
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[[python-package-tutorial]]
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+python-package+ tutorial
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^^^^^^^^^^^^^^^^^^^^^^^^^
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First, let's see how to write a +.mk+ file for a Python package,
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with an example :
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------------------------
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01: ################################################################################
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02: #
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03: # python-foo
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04: #
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05: ################################################################################
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06:
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07: PYTHON_FOO_VERSION = 1.0
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08: PYTHON_FOO_SOURCE = python-foo-$(LIBFOO_VERSION).tar.xz
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09: PYTHON_FOO_SITE = http://www.foosoftware.org/download
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10: PYTHON_FOO_LICENSE = BSD-3c
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11: PYTHON_FOO_LICENSE_FILES = LICENSE
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12: PYTHON_FOO_ENV = SOME_VAR=1
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13: PYTHON_FOO_DEPENDENCIES = libmad
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14: PYTHON_FOO_SETUP_TYPE = distutils
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15:
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16: $(eval $(python-package))
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------------------------
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On line 7, we declare the version of the package.
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On line 8 and 9, we declare the name of the tarball (xz-ed tarball
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recommended) and the location of the tarball on the Web. Buildroot
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will automatically download the tarball from this location.
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On line 10 and 11, we give licensing details about the package (its
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license on line 10, and the file containing the license text on line
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11).
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On line 12, we tell Buildroot to pass custom options to the Python
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+setup.py+ script when it is configuring the package.
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On line 13, we declare our dependencies, so that they are built
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before the build process of our package starts.
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On line 14, we declare the specific Python build system being used. In
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this case the +distutils+ Python build system is used. The two
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supported ones are +distutils+ and +setuptools+.
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Finally, on line 16, we invoke the +python-package+ macro that
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generates all the Makefile rules that actually allow the package to be
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built.
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[[python-package-reference]]
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+python-package+ reference
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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As a policy, packages that merely provide Python modules should all be
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named +python-<something>+ in Buildroot. Other packages that use the
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Python build system, but are not Python modules, can freely choose
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their name (existing examples in Buildroot are +scons+ and
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+supervisor+).
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In their +Config.in+ file, they should depend on +BR2_PACKAGE_PYTHON+
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so that when Buildroot will enable Python 3 usage for modules, we will
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be able to enable Python modules progressively on Python 3.
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The main macro of the Python package infrastructure is
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+python-package+. It is similar to the +generic-package+ macro. It is
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also possible to create Python host packages with the
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+host-python-package+ macro.
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Just like the generic infrastructure, the Python infrastructure works
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by defining a number of variables before calling the +python-package+
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or +host-python-package+ macros.
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All the package metadata information variables that exist in the
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xref:generic-package-reference[generic package infrastructure] also
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exist in the Python infrastructure: +PYTHON_FOO_VERSION+,
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+PYTHON_FOO_SOURCE+, +PYTHON_FOO_PATCH+, +PYTHON_FOO_SITE+,
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+PYTHON_FOO_SUBDIR+, +PYTHON_FOO_DEPENDENCIES+, +PYTHON_FOO_LICENSE+,
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+PYTHON_FOO_LICENSE_FILES+, etc.
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Note that:
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* Setting +PYTHON_FOO_INSTALL_STAGING+ to +YES+ has no effect (unless
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a +PYTHON_FOO_INSTALL_STAGING_CMDS+ variable is defined), since
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Python modules generally don't need to be installed to the
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+staging+ directory.
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* It is not necessary to add +python+ or +host-python+ in the
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+PYTHON_FOO_DEPENDENCIES+ variable of a package, since these basic
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dependencies are automatically added as needed by the Python
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package infrastructure.
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* Similarly, it is not needed to add +host-setuptools+ and/or
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+host-distutilscross+ dependencies to +PYTHON_FOO_DEPENDENCIES+ for
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setuptools-based packages, since these are automatically added by
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the Python infrastructure as needed.
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One variable specific to the Python infrastructure is mandatory:
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* +PYTHON_FOO_SETUP_TYPE+, to define which Python build system is used
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by the package. The two supported values are +distutils+ and
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+setuptools+. If you don't know which one is used in your package,
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look at the +setup.py+ file in your package source code, and see
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whether it imports things from the +distutils+ module or the
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+setuptools+ module.
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A few additional variables, specific to the Python infrastructure, can
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optionally be defined, depending on the package's needs. Many of them
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are only useful in very specific cases, typical packages will
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therefore only use a few of them, or none.
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* +PYTHON_FOO_ENV+, to specify additional environment variables to
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pass to the Python +setup.py+ script (for both the build and install
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steps). Note that the infrastructure is automatically passing
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several standard variables, defined in +PKG_PYTHON_DISTUTILS_ENV+
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(for distutils target packages), +HOST_PKG_PYTHON_DISTUTILS_ENV+
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(for distutils host packages), +PKG_PYTHON_SETUPTOOLS_ENV+ (for
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setuptools target packages) and +HOST_PKG_PYTHON_SETUPTOOLS_ENV+
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(for setuptools host packages).
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* +PYTHON_FOO_BUILD_OPT+, to specify additional options to pass to the
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Python +setup.py+ script during the build step. For target distutils
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packages, the +PKG_PYTHON_DISTUTILS_BUILD_OPT+ options are already
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passed automatically by the infrastructure.
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* +PYTHON_FOO_INSTALL_OPT+, to specify additional options to pass to
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the Python +setup.py+ script during the installation step. Note that
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the infrastructure is automatically passing some options, defined in
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+PKG_PYTHON_DISTUTILS_INSTALL_OPT+ (for target distutils packages),
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+HOST_PKG_PYTHON_DISTUTILS_INSTALL_OPT+ (for host distutils
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packages), +PKG_PYTHON_SETUPTOOLS_INSTALL_OPT+ (for target
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setuptools packages) and +HOST_PKG_PYTHON_SETUPTOOLS_INSTALL_OPT+
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(for host setuptools packages).
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With the Python infrastructure, all the steps required to build and
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install the packages are already defined, and they generally work well
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for most Python-based packages. However, when required, it is still
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possible to customize what is done in any particular step:
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* By adding a post-operation hook (after extract, patch, configure,
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build or install). See xref:hooks[] for details.
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* By overriding one of the steps. For example, even if the Python
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infrastructure is used, if the package +.mk+ file defines its own
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+PYTHON_FOO_BUILD_CMDS+ variable, it will be used instead of the
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default Python one. However, using this method should be restricted
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to very specific cases. Do not use it in the general case.
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