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Notes on EasyBuild HashDist conf call (20121126)

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boegel edited this page Nov 26, 2012 · 2 revisions
  • attending conf call: Dag Sverre Seljebotn, Jens Timmerman, Kenneth Hoste

HashDist in general

  • goalf of HashDist: switch software stacks like you could switch git branches
  • hash includes build configuration, dependencies, OS, ...
  • NIX/GNIX goes very far, they include everything in the hash
  • goal of HashDist is not that extreme
  • software installations are done in prefix path that includes hash
  • software stack is then a profile that combines a bunch of these packages together
  • updating is simply building what's missing and updating the profiles
  • previous builds are cached, HashDist detects what was built before and reuses those builds
  • initial version will be specific to HPC, but intention is to support also OS X, Windows, ...

HashDist and EasyBuild

  • HashDist is not meant to be user-facing, but more intended like an internal package managing tool
  • e.g. for software like Sage that manages a whole bunch of (sub)packages itself
  • in one sense, HashDist is more like a replacement for environment modules
  • supporting HashDist in EasyBuild would be a bit more invasive than the support for environment modules
  • e.g. HashDist would want control over the installation prefix
  • easy to add by putting the required hooks in place in EasyBuild
  • EasyBuild could serve as an example of how to integrate HashDist into existing tools

summarized

HashDist is basically a list of 4 tools:

  1. LD_PRELOAD tool to figure out whether system libraries not explicitely specified are being used for build
  • e.g. "LD_PRELOAD=jail.so gcc ..."
  1. manager of db of installation prefixes based on hashes
  2. make symlinked profiles that represent a software stack
  • more complex for e.g. Python
  • you would need to make the 'python' binary search for packages in paths other than the ones in the Python search path
  • by writing a wrapper around python, or wrapping around the loader that looks for the required packages
  • setting LD_LIBRARY_PATH may break stuf, especially on a desktop environment
  • e.g. printing to a printer from Python code, using a self-built Python distribution (e.g. using EasyBuild)
  • instead of setting LD_LIBRARY_PATH, you could link with -Wl,-R${ORIGIN}/../../<hash>
  • ${ORIGIN} will be replaced with actual location of library, making stuff relocatable just like with setting LD_LIBRARY_PATH
  1. an alternative for environment modules, that would also work in non-HPC environments

licensing

  • GPLv2 license is an issue in the Python scientific software community, which is very much BSD
  • if EasyBuild wants to become the defacto standard in the Python community, reclicensing would probably be required
  • HashDist (support) would have to be in a separate repo
  • we should contact NUMfocus mailing list, poll whether how much GPLv2 licensing would matter for a tool that is just to be used, cfr. Linux kernel

related stuff

  • python-hpcmp: DoD effort to package bunch of Python packages
  • they basically have a huge Makefile together with some config files
  • https://github.com/erdc-cm/python-hpcmp
  • WAF: build tool that does configure/building of software
  • support for building numpy/scipy support is in development, as an alternative to distutils
  • but distutils probably won't disappear, too much legacy
  • http://code.google.com/p/waf/
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