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
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
One comes across
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()
This is a problem for Python 3.5 (and other Python 3 versions) when
setup.py is executed by an interpreter run in a non-UTF-8 environment
:
$ 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
The reason for this error is, the default encoding for file object returned by
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'>
Non-UTF-8 build environments because
$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=
A problem like this is solved mostly elegant by installing some workaround in
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
This problem ideally should be
taken care of upstream.
In Python 3, the default
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()
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 3
.
It was revealed that there were differences in the sorting order of the
[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
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
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)
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
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]
The result, the new
_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': ()
That list comprehension iterates over the other dictionary entries to gather the value of
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)
In comparison to the list method
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.
During this year s ESSLLI (European Summer School in Logic, Language and Information) I was teaching a course on Algebraic Specification and Verification with CafeOBJ. Now that the course is over I can relax a bit and enjoy the beauty of the surrounding North Tyrol.
For those who couldn t attend the ESSLLI or the course, here are the course materials:
Once I got 
I read this tweet a couple of weeks ago:
To be clear: for Stretch we recommend that reproducible builds are done in the same build path as the "original" build.
Finally, and just for our future references, when we enabled build path variation on Saturday, August 20th 2016, the numbers for unstable were:
As you may already know, next DebConf will be held at Coll ge de Maisonneuve in Montreal from August 6 to August 12, 2017. We are already thinking about the conference schedule, and the content team is open to suggestions for invited speakers.
Priority will be given to speakers who are not regular DebConf attendees, who are more likely to bring diverse viewpoints to the conference.
Please keep in mind that some speakers may have very busy schedules and need to be booked far in advance. So, we would like to start inviting speakers in the middle of September 2016.
If you would like to suggest a speaker to invite, please follow the procedure described on the 
A release of 
From the list of new packages I want to pick out the group of phf* packages that seem from a quick reading over the package documentations as very interesting.
But most important is the incorporation of tex4ht into the TeX Live packages, so please report bugs and shortcomings to the BTS. Thanks.
New packages
Gathering from some recent discussions it seems to be not that well
known that 