An attempt to better manage dependencies in requirements files inspired by Ruby's Gem Bundler
Pundler is an attempt to better manage python requirements files.
Pundler is inspired by Ruby’s Gem Bundler.
Specifically the goal is to process requirements.in or requirements.txt into a frozen lock file similar to Gemfile and Gemfile.lock in the ruby world.
The advantage of doing something like this is that your requirements file specifies only versions of things that you specifically depend on and dependencies brought in by those dependencies can be easily identified and separated out.
For example, if I install the requirement jinja2==2.7 I don’t actually care about also installing jinja2’s dependency markupsafe but it will be installed. By running Pundler I end up with a nicely pinned requirements.txt that I can just regenerate from my “real” requirements.in whenever requirements I actually care about change.
For example, say I have in requirements.in:
a==1.0 b==2.0 c==3.0
And if we include the dependencies of those packages we have:
a==1.0 adep1==1.0 adep2==1.0 b==2.0 bdep1==2.0 c==3.0
Say we eventually upgrade a to version 2.0:
a==2.0 adep1==1.0 adep2==1.0 b==2.0 bdep1==2.0 c==3.0
In a==2.0 the dependency adep1==1.0 is no longer needed. If we have one requirements file with all versions pinned it isn’t clear that that dependency can now be removed.
If instead we simply updated the original requirements.in we could regenerate the full requirements (as a requirements.txt) and it would be clear that adep1==1.0 was no longer required.
Simply run pundler in a directory with your requirements.in:
python setup.py develop pundler
Pundler will process the file and create a requirements.txt that has all packages pinned to specific versions and identifies clearly what depends on what packages depend on what.
Given the following requirements.example.in:
pyramid==1.4.2 jinja2 txtemplate
Pundler will generate the this requirements.example.txt:
# requirement 'pyramid==1.4.2' depends on: WebOb==1.2.3 pyramid==1.4.2 translationstring==1.1 repoze.lru==0.6 Mako==0.8.1 MarkupSafe==0.18 PasteDeploy==1.5.0 Chameleon==2.11 venusian==1.0a8 zope.deprecation==4.0.2 zope.interface==4.0.5 setuptools==0.6c11 # requirement 'jinja2' depends on: jinja2==2.7 markupsafe==0.18 # requirement 'txtemplate' depends on: genshi==0.7 #jinja2==2.7 twisted==13.0.0 #markupsafe==0.18 txtemplate==1.0.2 #zope.interface==4.0.5 #setuptools==0.6c11