:warning: Python 2 will soon be unsupported and removed from the feed - see below :warning:
This section describes specifics for the Python packages that are present in this repo, and how things are structured.
In terms of license, contributing guide, etc, all of that information is described in the top README.md file, and it applies here as well. This document attempts to cover only technical aspects of Python/Python3 packages, and maybe some explanations about how things are (and why they are as they are).
Python 2 will not be maintained past 1 January 2020. As such, we will be transitioning Python 2 programs and libraries to Python 3, and Python 2 packages will be removed in early 2020.
(Discussion for how to handle this transition can be found in #8520.)
A mass removal event ("The Snap") will occur on 31 March 2020, or 2 weeks before the freeze for a 20.x release, whichever is sooner. The exact date will be confirmed when the 20.x release schedule is known, or by 15 March 2020.
All Python 2 packages (the Python 2 interpreter, programs that depend on Python 2, and Python 2-only libraries) will be removed during this event.
Leading up to "The Snap":
In general, new Python 2 packages are no longer accepted
The Python 2 interpreter will remain in the feed until "The Snap"
Programs that depend on Python 2 will be transitioned to Python 3 (see #8893)
Python 2 libraries will remain in the feed until "The Snap"
This sub-tree came to exist after a number of contributions (Python packages) were made to this repo, and the lang subtree grew to a point where a decision was made to move all Python packages under lang/python.
It contains the 2 Python interpreters (Python & Python3) and Python packages. Most of the Python packages are downloaded from pypi.org. Python packages from pypi.org are typically preferred when adding new packages.
If more packages (than the ones packaged here) are needed, they can be downloaded via pip or pip3. Note that the versions of pip & setuptools [available in this repo] are the ones that are packaged inside the Python & Python3 packages (yes, Python & Python3 come packaged with pip & setuptools).
In the feeds.conf (or feeds.conf.default file, whatever is preferred), the packages repo should be present.
Example
src-git packages https://git.openwrt.org/feed/packages.git
src-git luci https://git.openwrt.org/project/luci.git
src-git routing https://git.openwrt.org/feed/routing.git
src-git telephony https://git.openwrt.org/feed/telephony.git
#
#
src-git someotherfeed https://github.com/<github-user>/<some-other-package>
Assuming that there are Python packages in the <some-other-package>, they should include python[3]-package.mk like this:
include $(TOPDIR)/feeds/packages/lang/python/python-package.mk
include $(TOPDIR)/feeds/packages/lang/python/python3-package.mk
Same rules apply for python[3]-package.mk as the Python packages in this repo.
And if only 1 of python-package.mk or python3-package.mk is needed, then only the needed mk file should be included (though it's not an issue if both are included).
One important consideration:: if the local name is not packages, it's something else, like openwrt-packages. And in feeds.conf[.default] it's:
src-git openwrt-packages https://git.openwrt.org/feed/packages.git
Then, the inclusions also change:
include $(TOPDIR)/feeds/openwrt-packages/lang/python/python-package.mk
include $(TOPDIR)/feeds/openwrt-packages/lang/python/python3-package.mk
Each maintainer[s] of external packages feeds is responsible for the local name, and relative inclusion path back to this feed (which is named packages by default).
In case there is a need/requirement such that the local package feed is named something else than packages, one approach to make the package flexible to change is:
PYTHON_PACKAGE_MK:=$(wildcard $(TOPDIR)/feeds/*/lang/python/python-package.mk)
# verify that there is only one single file returned
ifneq (1,$(words $(PYTHON_PACKAGE_MK)))
ifeq (0,$(words $(PYTHON_PACKAGE_MK)))
$(error did not find python-package.mk in any feed)
else
$(error found multiple python-package.mk files in the feeds)
endif
else
$(info found python-package.mk at $(PYTHON_PACKAGE_MK))
endif
include $(PYTHON_PACKAGE_MK)
Same can be done for python3-package.mk.
This should solve the corner-case where the python[3]-package.mk can be in some other feed, or if the packages feed will be named something else locally.
In order to build the Python[3] interpreters, a host Python/Python3 interpreter needs to be built, in order to process some of the build for the target Python/Python3 build. The host Python[3] interpreters are also needed so that Python bytecodes are generated, so the host interpreters need to be the exact versions as on the target. And finally, the host Python[3] interpreters also provide pip & pip3, so that they may be used to install some Python[3] packages that are required to build other Python[3] packages. That's why you'll also see a Python/Python3 build & staging directories.
As you're probably thinking, this sounds [and is] somewhat too much complication [just for packaging], but the status of things is-as-it-is, and it's probably much worse than what's currently visible on the surface [with respect to packaging Python[3] & packages].
As mentioned earlier, Python[3] packages are shipped with bytecodes, and the reason for this is simply performance & size. The thought/discussion matrix derives a bit like this:
python-src & python3-src can be provided for people that want the source codeBy default, automatic Python[3] byte-code generation is disabled when running a Python script, in order to prevent a disk from accidentally filling up. Since some disks reside in RAM, this also means not filling up the RAM. If someone wants to convert Python source to byte-code then he/she is free to compile it [directly on the device] manually via the Python interpreter & library.
The basis of all these packages are:
These 2 are normal OpenWrt packages, which will build the Python interpreters. They also provide python[3]-pip & python[3]-setuptools. Each Python or Python3 package is actually split into multiple sub-packages [e.g. python-email, python-sqlite3, etc]. This can be viewed inside lang/python/python/files & lang/python/python3/files.
The reason for this splitting, is purely to offer a way for some people to package Python/Python3 in as-minimal-as-possible-and-still-runable way, and also to be somewhat maintainable when packaging. A standard Python[3] installation can take ~20-30 MBs of disk, which can be somewhat big for some people, so there are the python[3]-base packages which bring that down to ~5 MBs. This seems to be good enough (and interesting) for a number of people.
The Python[3] interpreters are structured like this:
python-base (and python3-base), which is just the minimal package to startup Python[3] and run basic commandspython (and python3) are meta-packages, which install almost everything (python[3]-base [plus] Python[3] library [minus] some unit-tests & some windows-y things)python-light (and python3-light) are python (and python3) [minus] packages that are in lang/python/python/files or lang/python/python3/files ; the size of these 2 packages may be sensible (and interesting) to another group of peopleAll other Python & Python3 packages (aside from the 2 intepreters) typically use these files:
Note that Python/Python3 packages don't need to use these files (i.e. python[3]-package.mk & python[3]-host.mk), but they do provide some ease-of-use & reduction of duplicate code, especially when packaging for both Python & Python3. And they do contain some learned-lessons about packaging Python/Python3 packages, so it's a good idea to use them.
A Python package can be packaged for either Python or Python3 or both.
This section will describe both, and then it can be inferred which is for which.
Packaging for both Python & Python3 uses the VARIANT mechanism for packaging inside OpenWrt. (#### FIXME: find a link for this later if it exists)
It's important when packaging for both Python & Python3 to override this variable, so that the build directory differs for each variant.
Typically it's just something like:
PKG_BUILD_DIR:=$(BUILD_DIR)/$(BUILD_VARIANT)-pyasn1-$(PKG_VERSION)
Where pyasn1 should be some other name, or maybe PKG_NAME
This should be added before this include:
include $(INCLUDE_DIR)/package.mk
In many cases, this needs to be overriden. This is usually because the way Python packages are archived, don't follow the convention of other tar.gz packages.
So, something like:
PKG_UNPACK=$(HOST_TAR) -C $(PKG_BUILD_DIR) --strip-components=1 -xzf $(DL_DIR)/$(PKG_SOURCE)
should be added.
It's not important whether this is after or before include $(INCLUDE_DIR)/package.mk
If packaging for Python, add this after include $(INCLUDE_DIR)/package.mk
include ../python-package.mk
If packaging for Python3, add this after include $(INCLUDE_DIR)/package.mk
include ../python3-package.mk
Order doesn't matter between python-package.mk & python3-package.mk.
These will make sure that build rules for Python or Python3 can be specified and picked up for build.
This part is similar to default OpenWrt packages.
It's usually recommended to have a Package/<PKG_NAME>/Default section that's common for both Python & Python3.
Example:
define Package/python-lxml/Default
SECTION:=lang
CATEGORY:=Languages
SUBMENU:=Python
URL:=https://lxml.de
DEPENDS:=+libxml2 +libxslt +libexslt
endef
Then for each variant do something like:
define Package/python-lxml
$(call Package/python-lxml/Default)
TITLE:=python-lxml
DEPENDS+=+PACKAGE_python-lxml:python-light +PACKAGE_python-lxml:python-codecs
VARIANT:=python
endef
define Package/python3-lxml
$(call Package/python-lxml/Default)
TITLE:=python3-lxml
DEPENDS+=+PACKAGE_python3-lxml:python3-light
VARIANT:=python3
endef
Some considerations here (based on the example above):
DEPENDS are correct for both variants; as seen in the example above, python-codecs is needed only for python-lxml (see note-encodings)+PACKAGE_python-lxml:<dep> as seen in the above example ; the reason for this is build-time reduction ; if you want to build Python3 only packages, this won't build Python & Python packages + dependencies ; this is a known functionality of OpenWrt build deps
+PACKAGE_python-lxml conditional deps creates circular dependencies, then open an issue so this can be resolved again.VARIANT=python or VARIANT=python3 must be addedPackage/python-<something> & Package/python3-<something> ; this convention makes things easier to follow, though it could work without naming things this wayTITLE can be something a bit more verbose/neat ; typically the name is short as seen abovenote-encodings: That's because some character encodings are needed, which are present in python3-base but not in python-light (but are present in python-codecs) ; this is because Python3 is designed to be more Unicode friendly than Python2 (it's one of the fundamental differences between the 2), and Python3 won't start without those encodings being present.
Following these, 2 more definitions are required:
define Package/python-lxml/description
The lxml XML toolkit is a Pythonic binding
for the C libraries libxml2 and libxslt.
endef
define Package/python3-lxml/description
$(call Package/python-lxml/description)
.
(Variant for Python3)
endef
Typically, the description is the same for both, so just mentioning that one is a variant of the other is sufficient.
If all the above prerequisites have been met, all that's left is:
$(eval $(call PyPackage,python-lxml))
$(eval $(call BuildPackage,python-lxml))
$(eval $(call Py3Package,python3-lxml))
$(eval $(call BuildPackage,python3-lxml))
The $(eval $(call PyPackage,python-lxml)) part will instantiate all the default Python build rules so that the final Python package is packaged into an OpenWrt.
And $(eval $(call BuildPackage,python-lxml)) will bind all the rules generated with $(eval $(call PyPackage,python-lxml)) into the OpenWrt build system.
These packages will contain byte-codes and binaries (shared libs & other stuff).
If a user wishes to ship source code, adding 2 more lines creates 2 more packages that ship Python source code:
$(eval $(call PyPackage,python-lxml))
$(eval $(call BuildPackage,python-lxml))
$(eval $(call BuildPackage,python-lxml-src))
$(eval $(call Py3Package,python3-lxml))
$(eval $(call BuildPackage,python3-lxml))
$(eval $(call BuildPackage,python3-lxml-src))
The name *-src must be the Python package name; so for python-lxml-src a equivalent python-lxml name must exist.
Some packages need custom build rules (because they do).
The default package build and install processes are defined in python[3]-package.mk.
The default build process calls setup.py install inside the directory where the Python source package is extracted (PKG_BUILD_DIR). This "installs" the Python package to an intermediate location (PKG_INSTALL_DIR) where it is used by the default install process.
There are several Makefile variables that can be used to customize this process (all optional):
PYTHON_PKG_SETUP_DIR / PYTHON3_PKG_SETUP_DIR: Path where setup.py can be found, relative to the package directory (PKG_BUILD_DIR).setup.py is in the package directory)PYTHON_PKG_SETUP_VARS / PYTHON3_PKG_SETUP_VARS: Additional environment variables to set for the call to setup.py. Should be in the form of VARIABLE1=value VARIABLE2=value ....PYTHON_PKG_SETUP_GLOBAL_ARGS / PYTHON3_PKG_SETUP_GLOBAL_ARGS: Additional command line arguments to pass to setup.py, before / in front of the install command.PYTHON_PKG_SETUP_ARGS / PYTHON3_PKG_SETUP_ARGS: Additional command line arguments to pass to setup.py, after the install command.--single-version-externally-managedConceptually, these variables are used in this way (using a Python 2 package as an example):
cd $(PKG_BUILD_DIR)/$(PYTHON_PKG_SETUP_DIR)
$(PYTHON_PKG_SETUP_VARS) python setup.py $(PYTHON_PKG_SETUP_GLOBAL_ARGS) install $(PYTHON_PKG_SETUP_ARGS)
The default build process can be completely overridden by defining custom PyBuild/Compile & Py3Build/Compile rules in the package Makefile.
The default install process copies some/all of the files from PKG_INSTALL_DIR, placed there by the build process, to a location passed to the install rule as the first argument ($(1)). The OpenWrt build system will then take those files and create the actual .ipk package archives.
This default process uses 2 build rules:
PyPackage/<package>/filespec & Py3Package/<package>/filespec which are Python library files relative to /usr/lib/pythonX.Y ; by default this is /usr/lib/python$(PYTHON[3]_VERSION)/site-packages (PYTHON[3]_PKG_DIR) ; most Python[3] packages generate files that get installed in this sub-folderPyPackage/<package>/install & Py3Package/<package>/install is similar to Package/<package>/install ; these allow binary (or other files) to be installed on the targetBoth the 2 above rules generate a Package/<package>/install build rule, which gets picked up by the build system. Both can be used together (they are not mutually exclusive), and provide a good enough flexibility for specifying Python[3] packages.
The PyPackage/<package>/filespec & Py3Package/<package>/filespec rules contain one or more lines of the following format (whitespace added for clarity):
<one of: +-=> | <file/directory path> | <file permissions>
The initial character controls the action that will be taken:
+: Install the given path. If the path is a directory, all files and subdirectories inside are installed.
-: Remove the given path. Useful when most of a directory should be installed except for a few files or subdirectories.
=: Assign the given file permissions to the given path. File permissions is required in this case.As mentioned, the default PyPackage/<package>/filespec & Py3Package/<package>/filespec install PYTHON[3]_PKG_DIR:
define PyPackage/python-example/filespec
+|$(PYTHON_PKG_DIR)
endef
If there is an examples directory and test_*.py files that can be omitted to save space, this can be specified as:
define PyPackage/python-example/filespec
+|$(PYTHON_PKG_DIR)
-|$(PYTHON_PKG_DIR)/examples
-|$(PYTHON_PKG_DIR)/test_*.py
endef
These can be installed via pip and ideally they should only be installed like this, because it's a bit simpler than running them through the OpenWrt build system. Build variants on the host-side build are more complicated (and nearly impossible to do sanely) in the current OpenWrt build system.
Which is why [for example] if you need python cffi on the host build, it's easier to just add it via:
HOST_PYTHON_PACKAGE_BUILD_DEPENDS:="cffi==$(PKG_VERSION)"
HOST_PYTHON3_PACKAGE_BUILD_DEPENDS:="cffi==$(PKG_VERSION)"
[cffi is one of those packages that needs a host-side package installed for both Python & Python3].
This works reasonably well in the current OpenWrt build system, as binaries get built for this package and get installed in the staging-dir $(STAGING_DIR)/usr/lib/pythonX.Y/site-packages.