Daniel Stender: Collected notes from Python packaging
Here are some collected notes on some particular problems from packaging Python stuff for Debian, and more are coming up like this in the future.
Some of the issues discussed here might be rather simple and even benign for the experienced packager, but maybe this is be helpful for people coming across the same issues for the first time, wondering what's going wrong.
But some of the things discussed aren't easy.
Here are the notes for this posting, there is no particular order.
UnicodeDecoreError on open() in Python 3 running in non-UTF-8 environments
I've came across this problem again recently packaging httpbin 0.5.0.
The build breaks the following way e.g. trying to build with sbuild in a chroot,
that's the first run of
One comes across
This is a problem for Python 3.5 (and other Python 3 versions) when
The reason for this error is, the default encoding for file object returned by
Non-UTF-8 build environments because
A problem like this is solved mostly elegant by installing some workaround in
This problem ideally should be taken care of upstream.
In Python 3, the default
non-deterministic order of requirements in egg-info/requires.txt
This problem appeared in prospector/0.11.7-5 in the reproducible builds test builds, that was the first package of Prospector running on Python 32.
It was revealed that there were differences in the sorting order of the
Reproducible builds folks recognized this to be a toolchain problem and set up the issue randonmness_in_python_setuptools_requires.txt to cover this.
Plus, a wishlist bug against python-setuptools was filed to fix this.
The patch which was provided by Chris Lamb adds sorting of dependencies in
O.k. In the toolchain, nothing sorts these requirements alphanumerically to make differences disappear, but what is the reason for these differences in the Prospector packages, though?
The problem is somewhat subtle.
In
The result, the new
That list comprehension iterates over the other dictionary entries to gather the value of
In comparison to the list method
setup.py with the default Python 3 interpreter:
I: pybuild base:184: python3.5 setup.py clean Traceback (most recent call last): File "setup.py", line 5, in <module> os.path.join(os.path.dirname(__file__), 'README.rst')).read() File "/usr/lib/python3.5/encodings/ascii.py", line 26, in decode return codecs.ascii_decode(input, self.errors)[0] UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 2386: ordinal not in range(128) E: pybuild pybuild:274: clean: plugin distutils failed with: exit code=1: python3.5 setup.py clean
UnicodeDecodeError-s quite oftenly on different occasions,
mostly related to Python 2 packaging (like here).
Here it's the case that in setup.py the long_description is tried to be read from the opened UTF-8 encoded file README.rst:
long_description = open(
os.path.join(os.path.dirname(__file__), 'README.rst')).read()
setup.py is executed by an interpreter run in a non-UTF-8 environment1:
$ LANG=C.UTF-8 python3.5 setup.py clean running clean $ LANG=C python3.5 setup.py clean Traceback (most recent call last): File "setup.py", line 5, in <module> os.path.join(os.path.dirname(__file__), 'README.rst')).read() File "/usr/lib/python3.5/encodings/ascii.py", line 26, in decode return codecs.ascii_decode(input, self.errors)[0] UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 2386: ordinal not in range(128) $ LANG=C python2.7 setup.py clean running clean
open() e.g. in
Python 3.5 is platform dependent, so that read() fails on that when there's a mismatch:
>>> readme = open('README.rst')
>>> readme
<_io.TextIOWrapper name='README.rst' mode='r' encoding='ANSI_X3.4-1968'>
$LANG isn't particularly set at all or set to C are common or even default in Debian packaging, like in the continuous integration resp. test building for reproducible builds the primary environment features that (see here).
That's also true for the base system of the sbuild environment:
$ schroot -d / -c unstable-amd64-sbuild -u root (unstable-amd64-sbuild)root@varuna:/# locale LANG= LANGUAGE= LC_CTYPE="POSIX" LC_NUMERIC="POSIX" LC_TIME="POSIX" LC_COLLATE="POSIX" LC_MONETARY="POSIX" LC_MESSAGES="POSIX" LC_PAPER="POSIX" LC_NAME="POSIX" LC_ADDRESS="POSIX" LC_TELEPHONE="POSIX" LC_MEASUREMENT="POSIX" LC_IDENTIFICATION="POSIX" LC_ALL=
debian/rules.
A quick and easy fix is to add export LC_ALL=C.UTF-8 here, which supersedes the locale settings of the build environment.
$LC_ALL is commonly used to change the existing locale settings, it overrides all other locale variables with the same value (see here).
C.UTF-8 is an UTF-8 locale which is available by default in a base system, it could be used without installing the locales package (or worse, the huge locales-all package):
(unstable-amd64-sbuild)root@varuna:/# locale -a C C.UTF-8 POSIX
open() is io.open(), for which the specific encoding could be given, so that the UnicodeDecodeError disappears.
Python 2 uses os.open() for open(), which doesn't support that, but has io.open(), too.
A fix which works for both Python branches goes like this:
import io long_description = io.open( os.path.join(os.path.dirname(__file__), 'README.rst'), encoding='utf-8').read()
[with_everything] dependencies resp. requirements in prospector-0.11.7.egg-info/requires.txt if the package was build on varying systems:
$ debbindiff b1/prospector_0.11.7-5_amd64.changes b2/prospector_0.11.7-5_amd64.changes ... prospector_0.11.7-5_all.deb file list @@ -1,3 +1,3 @@ -rw-r--r-- 0 0 0 4 2016-04-01 20:01:56.000000 debian-binary --rw-r--r-- 0 0 0 4343 2016-04-01 20:01:56.000000 control.tar.gz +-rw-r--r-- 0 0 0 4344 2016-04-01 20:01:56.000000 control.tar.gz -rw-r--r-- 0 0 0 74512 2016-04-01 20:01:56.000000 data.tar.xz control.tar.gz control.tar ./md5sums md5sums Files in package differ data.tar.xz data.tar ./usr/share/prospector/prospector-0.11.7.egg-info/requires.txt @@ -1,12 +1,12 @@ [with_everything] +pyroma>=1.6,<2.0 frosted>=1.4.1 vulture>=0.6 -pyroma>=1.6,<2.0
requires.txt for Setuptools by adding sorted() (stdlib) to _write_requirements() in command/egg_info.py:
--- a/setuptools/command/egg_info.py +++ b/setuptools/command/egg_info.py @@ -406,7 +406,7 @@ def warn_depends_obsolete(cmd, basename, filename): def _write_requirements(stream, reqs): lines = yield_lines(reqs or ()) append_cr = lambda line: line + '\n' - lines = map(append_cr, lines) + lines = map(append_cr, sorted(lines)) stream.writelines(lines)
setup.py, [with_everything] is a dictionary entry of _OPTIONAL (which is used for extras_require) that is created by a list comprehension out of the other values in that dictionary.
The code goes like this:
_OPTIONAL =
'with_frosted': ('frosted>=1.4.1',),
'with_vulture': ('vulture>=0.6',),
'with_pyroma': ('pyroma>=1.6,<2.0',),
'with_pep257': (), # note: this is no longer optional, so this option will be removed in a future release
_OPTIONAL['with_everything'] = [req for req_list in _OPTIONAL.values() for req in req_list]
_OPTIONAL dictionary including the key with_everything (which w/o further sorting is the source of the list of requirements requires.txt) e.g. looks like this (code snipped run through in my IPython):
In [3]: _OPTIONAL
Out[3]:
'with_everything': ['vulture>=0.6', 'pyroma>=1.6,<2.0', 'frosted>=1.4.1'],
'with_vulture': ('vulture>=0.6',),
'with_pyroma': ('pyroma>=1.6,<2.0',),
'with_frosted': ('frosted>=1.4.1',),
'with_pep257': ()
with_everything, and Python programmers know that of course dictionaries are not indexed and therefore the order of the key-value pairs isn't fixed, but is determined by certain conditions.
That's the source for the non-determinism of this Debian package revision of Prospector.
This problem has been fixed by a patch,
which just presorts the list of requirements before it gets added to _OPTIONAL:
@@ -76,8 +76,8 @@
'with_pyroma': ('pyroma>=1.6,<2.0',),
'with_pep257': (), # note: this is no longer optional, so this option will be removed in a future release
-_OPTIONAL['with_everything'] = [req for req_list in _OPTIONAL.values() for req in req_list]
-
+with_everything = [req for req_list in _OPTIONAL.values() for req in req_list]
+_OPTIONAL['with_everything'] = sorted(with_everything)
sort(), the function sorted() does not change iterables in-place, but returns a new object.
Both could be used.
As a side note, egg-info/requires.txt isn't even needed, but that's another issue.
I mentioned this briefly yesterday, but now I'll try to summarize the
story of a great surprise and a big moment for me.
The Debian Python Modules Team is 
And while I was on it, I thought I could do the same for the GNOME and GStreamer teams:
(hint: pox-guest and piotr in python-modules are the same person)
* Congrats to 