Build tensorflow from source not whl files.

[jjhelmus]

Currently the tensorflow recipe is repackaging the whl files provided by Google into conda packages. The whl files link against a newer version of glibc which limited what Linux distribution that the conda package works on and are only available for Python 2.7 and 3.4 on Linux.

A "better" solution would be to build the package from source, but this requires installing Bazel which requires Java JDK 8. I have successfully built a conda package for 0.8.0 from source using a Ubunutu 14.04 Docker container with Java+Bazel. We could do the same here but it would require quite a bit of customization of this feedstock. Anyone have opinion on this topic?

[rgommers]

There's 3 people reporting at numpy/numpy#8076 that installing tensorflow breaks numpy, and it looks related to this wheel repackaging business.

[rgommers]

This comment says that indeed tensorflow pulls in a numpy wheel somehow. So that's pretty badly broken.

[jakirkham]

Ouch! Yeah the build situation here is not great. It is unfortunately quite difficult to build tensorflow from source. That said, @jjhelmus added bazel recently (merged today), which should help.

[hajapy]

I'm a little confused, our build recipe installs tensorflow wheel via pip with --no-deps, so the only numpy should be one specified by the meta.yaml run time requirements.

[rgommers]

I also don't really understand it, but it's reported by 4 people so should be reproducible.

[jakirkham]

Of course, I think it is more surprise at the issue's existence than any doubt that people are running into an issue. Though you make a good point, steps to reproduce the issue would be very helpful in debugging it. Was that in the issue and I simply missed it?

[rgommers]

No, they all said "installed tensorflow with conda, then numpy broke". Asked for exact install commands.

[jakirkham]

Great, thanks Ralf.

[pgunn]

Is it possible to copy the build instructions from the non-conda-forge builds of tensorflow? Those versions don't seem to have the GLIBC version dependency (tested on RHEL7, which has a very dated glibc).

[jakirkham]

There is some work for this in PR ( #69 ). That said, this is not easy work. So please feel free to chip in if it is of interest and you have cycles.

[jjhelmus]

Done in #74