pkg_resources.require() throws a DistributionNotFound exception if python-setuptools is not installed

[Gediminas Paulauskas]

Many packages now depend only on python-pkg-resources and not python-setuptools, so the latter may be removed if it was automatically installed. However, in that case the whole mechanism stops working:

$ python
>>> import pkg_resources
>>> pkg_resources.require('zope.interface')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "pkg_resources.py", line 648, in require
    needed = self.resolve(parse_requirements(requirements))
  File "pkg_resources.py", line 546, in resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: distribute

This happens because zope.interface has setuptools in it's *.egg-info/requires.txt, like many other packages, but in reality only needs pkg_resources, and that's what is installed. Distribute is not needed at all, so it is a bug that this breaks in such a way.

ProblemType: Crash
DistroRelease: Ubuntu 10.04
Package: python-pastescript 1.7.3-5ubuntu1
ProcVersionSignature: Ubuntu 2.6.32-20.29-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-20-generic i686
NonfreeKernelModules: nvidia
Architecture: i386
Date: Wed Apr 14 13:12:48 2010
ExecutablePath: /usr/bin/paster
InterpreterPath: /usr/bin/python2.6
PackageArchitecture: all
ProcCmdline: python /usr/bin/paster serve --user=schooltool --group=schooltool --daemon --pid-file=/var/run/schooltool/schooltool-2009.pid --log-file=/var/log/schooltool/paste.log --quiet /etc/schooltool/schooltool-2009/paste.ini start
ProcEnviron: Error: [Errno 13] Permission denied: '/proc/32252/environ'
PythonArgs: ['/usr/bin/paster', 'serve', '--user=schooltool', '--group=schooltool', '--daemon', '--pid-file=/var/run/schooltool/schooltool-2009.pid', '--log-file=/var/log/schooltool/paste.log', '--quiet', '/etc/schooltool/schooltool-2009/paste.ini', 'start']
SourcePackage: pastescript
Title: paster crashed with DistributionNotFound in resolve()
UserGroups:

[Matthias Klose (doko)]

I'll fix that for zope.interface

> As far as I can see this bug only occurs when require()'ing a python package using python-central. python-support using package is found successfully

why would that make a difference?

[Launchpad Janitor (janitor)]

This bug was fixed in the package zope.interface - 3.5.3-1ubuntu1

---------------
zope.interface (3.5.3-1ubuntu1) lucid; urgency=low

  * The egg doesn't require setuptools. LP: #563060.
 -- Matthias Klose <email address hidden> Wed, 14 Apr 2010 15:47:40 +0200

[Gediminas Paulauskas (menesis)]

zope.interface was only an example of a package (there are many of them) that declares a dependency on setuptools (in egg-info/requires.txt) but only has python-pkg-resources dependency.

The purpose of the splitted python-pkg-resources package was to be used as a runtime dependency for exactly this purpose. But now this does not work. So this a regression of python-pkg-resources (distribute).

Also, sorry, python-support or python-central doesn't make a difference after all.

[Gediminas Paulauskas (menesis)]

Please revert the zope.interface "fix", it is wrong. The package should depend on python-pkg-resources (that is done automatically) because it installs a file that uses it:

$ cat src/zope/__init__.py
# this is a namespace package
try:
    import pkg_resources
    pkg_resources.declare_namespace(__name__)
except ImportError:
    import pkgutil
    __path__ = pkgutil.extend_path(__path__, __name__)

True, this is optional, but the preferred way to declare namespaces.

And it does not fix this crash at all.

[aguynamedben (benstandefer)]

Yes, this is a problem with python-pkg-resources (distribute), not zope.interface, and this affects me too. python-pylibmc does the same thing. When loading pylibmc through pkg_resources, I get DistributionNotFound: pylibmc. This bug is made even worse by the fact that in 10.04 you cannot actually get the real setuptools as a work-around because Ubuntu now gives you distribute when you ask for setuptools, so you're stuck with an impossible dependency.

[Neal McBurnett (nealmcb)]

I just got the same error when doing a setup.py sdist under lucid for my ElectionAudits project, which worked under Hardy. What is the status?

The workaround that seems to have worked for me is to apt-get install python-setuptools, so I'm confused by comment #6.

[Gediminas Paulauskas (menesis)]

Python packages that have 'setuptools' in they install_requires have this dependency translated to python-pkg-resources by van.pydeb. It works most of the time, except when pkg_resources.require is used (like paster from python-pastescript does). This was solved in Bug #572609.

So in the end the behaviour of van.pydeb that "fixed" http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=543551 is incorrect.

[Clive Darra (osde8info)]

see also https://bugs.launchpad.net/ubuntu/+source/funkload/+bug/659783

[Julian Taylor (jtaylor)]

this bug was reintroduced again into oneiric:
clean chroot:

$ apt-get install python-zope.interface

$ apt-cache policy python-zope.interface
python-zope.interface:
  Installed: 3.6.1-1build1
  Candidate: 3.6.1-1build1
  Version table:
 *** 3.6.1-1build1 0
        500 http://de.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages
        100 /var/lib/dpkg/status

$ python -c 'import pkg_resources; print pkg_resources.require("zope.interface")'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 654, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 552, in resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: distribute

[Gediminas Paulauskas (menesis)]

I have reverted the fix made in 3.5.3-1ubuntu1 when I packaged a newer version for maverick, because that solution (removing setuptools from requires.txt) is not sufficient, other zope.* packages also have setuptools in their setup.py install_requires and will have the same problem.

[Brian Sutherland (jinty)]

yes, this affects many packages (almost any namespace package) and should really be fixed at the build helper level.

We shouldn't need to apply the same patch to every zope.* package.

[Julian Taylor (jtaylor)]

this issue should be fixed by a rebuild due to the recent python-defaults sync:
https://launchpad.net/ubuntu/+source/python-defaults/2.7.2-4ubuntu1

python-defaults (2.7.2-2) experimental; urgency=low

  [ Piotr Ożarowski ]
    - remove setuptools from requires.txt (it is replaced with
      python-pkg-resources Debian dependency)

[Julian Taylor (jtaylor)]

this issue was fixed with rebuild due to the recent upload