Add pip to analysis releases, 1.0 branch (2017.11.28.)

While trying to make cookiecutter work on lxplus, I finally decided to just take a deep breath, and finally provide a functional pip installation as part of the analysis releases. Since analysers using Python have been asking for this for quite a while now.

I tested that with the update I was able to use pip for some basic installs on all of our regular installation platforms. Though I was probably not as thorough with this as I could've been...

@lheinric, this is how I'd solve the problem of using cookiecutter on lxplus. @will, you should know about this as well, as I'm modifying AthAnalysisExternals slightly as well. Finally, @ksuruliz should probably also see this change.

Hi @akraszna,

up to now I've done scl enable python27 in lxplus to get a shell that has pip/virtualenv installed for py27 (which then usually works w/ the analysis releases as well). But I agree installing pip as part of the release is very useful.

Jenkins Build SUCCESS

Results available at: Jenkins [AE-MERGE-REQUEST #282]

That's good to keep in mind. I myself only tried to set up Python 2.7 through AtlasLocalRootBase (lsetup python), but that didn't work. That didn't set up a different pip than /usr/bin/pip, so of course the command just failed.

Since people have been complaining since a while that they would like to use some python externals on the grid, this could potentially allow them to do so. As long as they tell pip explicitly in their run job to install stuff into the build directory, and not to the grid user's home directory. (I have no idea what sort of protections are in place against somebody doing that...)

Yeah pip install X --user should work. It would actually also be nice to add virtualenv

Okay, I pondered a bit in the last few hours whether I should really do things like this. But this still seems like a good thing to do, even if we end up using cookiecutter in some other way on lxplus.

As for virtualenv: Let's not bite off more than we can chew. Since I've never used virtualenv so far, I'll need a bit of convincing about that first...

merged

mentioned in commit 8d0c37a4

mentioned in commit 91b32f19

mentioned in merge request !194 (merged)