Python virtualenv --system-site-packages - 意外的pip行为

Question

I have a number of python services that each use virtualenvs. I sometimes rebuild these environments, and would like to save time doing it. mkvirtualenv --system-site-packages seems close to what I want, but it still has behavior I don't understand.

One package I use is gevent (beta version), which I install directly from GitHub: sudo pip install -e git://github.com/surfly/gevent.git@1.0b4#egg=gevent . This is done outside of a virtualenv, so it goes into the system's site-packages . This works fine, and if I create a new virtualenv with --system-site-packages , it seems to be present, but with a different rev and egg specified:

[msherry@hostname:~]$ mkvirtualenv test --system-site-packages
New python executable in test/bin/python2.7
Also creating executable in test/bin/python
Installing setuptools............done.
Installing pip...............done.
[msherry@hostname:~]$ workon test
[msherry@hostname:~]$ pip freeze|grep gevent
-e git://github.com/surfly/gevent.git@15418fc8ff4460069cf42b4b0341969c54455ddd#egg=gevent-dev

It at least looks installed, though. However, when I run pip install -e git://github.com/surfly/gevent.git@1.0b4#egg=gevent , the (slow) install process for gevent begins again -- it looks like I gain nothing by using --system-site-packages .

Ideally, I'd like pip to notice that the version of gevent I'm requesting is already present, and not try to install it again. Is there any way to do what I'm attempting?

Answer 1

When installing system wide, try a slightly different syntax.

sudo pip install git+git://github.com/surfly/gevent.git@1.0b4#egg=gevent

That is nearly the same as yours, except without the -e and includes the <vcs> prefix to your url. Without this, pip says

AssertionError: Sorry, 'git://github.com/surfly/gevent.git' is a malformed VCS url. The format is <vcs>+<protocol>://<url>, eg svn+http://myrepo/svn/MyApp#egg=MyApp

I also noticed the same thing you did when installing packages via pip in 'editable' mode: I get the commit hash version, as you did with the output of your pip freeze | grep gevent pip freeze | grep gevent

-e git://github.com/surfly/gevent.git@15418fc8ff4460069cf42b4b0341969c54455ddd#egg=gevent-dev

which corresponds to that version of gevent .