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On 4/23/2016 3:10 PM, Amrith Kumar wrote:
> The reason this change is being submitted is because people are advised
> to use upper-constraints.txt as the versions that have been tested but
> they don't always do that.
>
> As a result, blocking in requirements.txt is also recommended.

Yeah, good point, I've +2'ed Tony's versions of the backports since the 
commit messages were more correct per the backport process [1].

>
> Incidental to that, one thing that has always confused me about
> upper-constraints.txt has been the notion of capping. I notice that you
> say that "Routes in upper-constraints is capped at 2.2". I'm struck by
> the choice of the word 'capped'.
>
> When I was first debugging this problem with Routes, I ran this little
> experiment.
>
>         # Make a little venv for this test.
>
>         amrith at amrith-work:/tmp$ virtualenv t1
>         New python executable in /tmp/t1/bin/python
>         Installing setuptools, pip, wheel...done.
>         amrith at amrith-work:/tmp$ cd t1
>
>         # then activate it
>
>         amrith at amrith-work:/tmp/t1$ source bin/activate
>
>         # is Routes in the venv, it won't be ...
>
>         (t1) amrith at amrith-work:/tmp/t1$ pip freeze | grep Routes
>
>         # create some requirements and upper-constraints files
>
>         (t1) amrith at amrith-work:/tmp/t1$ cat requirements.txt
>         Routes!=2.0,!=2.1,<=2.3.0,>=1.12.3;python_version=='2.7' # MIT
>         (t1) amrith at amrith-work:/tmp/t1$ cat upper-constraints.txt
>         Routes===2.3.1
>
>         # install with those two ...
>
>         (t1) amrith at amrith-work:/tmp/t1$ pip install -c
>         upper-constraints.txt -r requirements.txt
>         Collecting Routes===2.3.1 (from -c upper-constraints.txt (line
>         1))
>         Collecting six (from Routes===2.3.1->-c upper-constraints.txt
>         (line 1))
>           Using cached six-1.10.0-py2.py3-none-any.whl
>         Collecting repoze.lru>=0.3 (from Routes===2.3.1->-c
>         upper-constraints.txt (line 1))
>         Installing collected packages: six, repoze.lru, Routes
>         Successfully installed Routes-2.3.1 repoze.lru-0.6 six-1.10.0
>
>         # what just happened?
>
>         (t1) amrith at amrith-work:/tmp/t1$ pip freeze | grep Routes
>         Routes==2.3.1
>         (t1) amrith at amrith-work:/tmp/t1$ python --version
>         Python 2.7.6
>
>
> I don't think upper-constraints.txt serves as an upper bound on the
> version of a library that must be used, rather as a constraint that
> overrides the requirements.txt file, EVEN IF IT CONTRADICTS IT.
>
> Above, notice that requirements.txt says <= 2.3.0 and
> upper-constraints.txt says 2.3.1, well 2.3.1 got installed.
>
> Or this ...
>
>         (t1) amrith at amrith-work:/tmp/t1$ pip uninstall Routes
>         Uninstalling Routes-2.3.1:
>           /tmp/t1/lib/python2.7/site-packages/Routes-2.3.1.dist-info/DESCRIPTION.rst
>           /tmp/t1/lib/python2.7/site-packages/Routes-2.3.1.dist-info/INSTALLER
>           /tmp/t1/lib/python2.7/site-packages/Routes-2.3.1.dist-info/METADATA
>           /tmp/t1/lib/python2.7/site-packages/Routes-2.3.1.dist-info/RECORD
>           /tmp/t1/lib/python2.7/site-packages/Routes-2.3.1.dist-info/WHEEL
>           /tmp/t1/lib/python2.7/site-packages/Routes-2.3.1.dist-info/metadata.json
>           /tmp/t1/lib/python2.7/site-packages/Routes-2.3.1.dist-info/top_level.txt
>           /tmp/t1/lib/python2.7/site-packages/routes/__init__.py
>           /tmp/t1/lib/python2.7/site-packages/routes/__init__.pyc
>           /tmp/t1/lib/python2.7/site-packages/routes/base.py
>           /tmp/t1/lib/python2.7/site-packages/routes/base.pyc
>           /tmp/t1/lib/python2.7/site-packages/routes/mapper.py
>           /tmp/t1/lib/python2.7/site-packages/routes/mapper.pyc
>           /tmp/t1/lib/python2.7/site-packages/routes/middleware.py
>           /tmp/t1/lib/python2.7/site-packages/routes/middleware.pyc
>           /tmp/t1/lib/python2.7/site-packages/routes/route.py
>           /tmp/t1/lib/python2.7/site-packages/routes/route.pyc
>           /tmp/t1/lib/python2.7/site-packages/routes/util.py
>           /tmp/t1/lib/python2.7/site-packages/routes/util.pyc
>         Proceed (y/n)? y
>           Successfully uninstalled Routes-2.3.1
>         (t1) amrith at amrith-work:/tmp/t1$ cat upper-constraints.txt
>         Routes===2.1
>         (t1) amrith at amrith-work:/tmp/t1$ pip install -c
>         upper-constraints.txt -r requirements.txt
>         Collecting Routes===2.1 (from -c upper-constraints.txt (line 1))
>         /tmp/t1/local/lib/python2.7/site-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:315: SNIMissingWarning: An HTTPS request has been made, but the SNI (Subject Name Indication) extension to TLS is not available on this platform. This may cause the server to present an incorrect TLS certificate, which can cause validation failures. For more information, see https://urllib3.readthedocs.org/en/latest/security.html#snimissingwarning.
>           SNIMissingWarning
>         /tmp/t1/local/lib/python2.7/site-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:120: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. For more information, see https://urllib3.readthedocs.org/en/latest/security.html#insecureplatformwarning.
>           InsecurePlatformWarning
>           Downloading Routes-2.1.tar.gz (179kB)
>             100% |################################| 184kB 2.1MB/s
>         Requirement already satisfied (use --upgrade to upgrade):
>         repoze.lru>=0.3 in ./lib/python2.7/site-packages (from
>         Routes===2.1->-c upper-constraints.txt (line 1))
>         Building wheels for collected packages: Routes
>           Running setup.py bdist_wheel for Routes ... done
>           Stored in
>         directory: /home/amrith/.cache/pip/wheels/84/93/eb/68589a0c49b27d9b3a4965c1d2d626235a0a4e03572772810b
>         Successfully built Routes
>         Installing collected packages: Routes
>         Successfully installed Routes-2.1
>         (t1) amrith at amrith-work:/tmp/t1$
>
> I think upper-constraints.txt doesn't cap requirements, it just
> overrides it ... Is that how it is supposed to work?

Probably going to need to chat with lifeless about this.

[1] 
http://docs.openstack.org/project-team-guide/stable-branches.html#proposing-fixes

-- 

Thanks,

Matt Riedemann