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HSF Packaging Meeting #37, 09 October, 2019

Agenda

https://indico.cern.ch/event/848215/

Participants: Ben Morgan, Graeme Stewart, Chris Green, Patrick Gartung, Javier Cervantes, Ben Couturier, Marco Clemencic, Chris Burr, André Sailer

Introduction (Graeme)

• Discussion on visit from CMake developers
  • Mostly on building C++ modules
  • Compiler needs to give enough information to build C++ modules, which needs better interfaces for passing information
• New CVMFS repo /cvmfs/sf.hsf.io
  • Stratum 0 at CERN
  • For any software of interest for wider use before production
  • Initial use for TAU performance tools from Tools WG -Contact Graeme if you have any packages you would like to add
• AOB:
  • Monday 14th Oct meeting of Tools WG on TAU utility
  • Looks particularly useful for mixed Python/C++
  • Next HSG/WLCG meeting 11-15th May 2020 in Lund, Sweden.
  • Next Packaging meeting: with CHEP and other commitments, suggest meeting in early December. As always, let Graeme and Ben know of any presentations
  • Chris G: Will distribute CHEP slides in the next week or so for comments

Best practices for package relocation (Ben)

• Still useful to do this well, even when taking into account helper scripts from package managers like Spack
• Relative paths good for “internal” items, but not for external dependencies
• External dependencies fixed with full paths
• argv[0] needs some help to fix corner cases, but it works
• binreloc will return a reliable absolute path
  • But it only works for dynamic libraries (not static)
• Python, Rust, Go provide “native” means to find paths
  • Some C/C++ toolkits do it (Qt, Poco)
  • But no absolutely general solution for C/C++, binreloc is the best current soluion
• Good practice to follow CMake guidelines
  • Write a FooConfig.cmake, not a FindFoo.cmake
  • CMake will help you!
• Use target properties, not fiddling with CMake path variables directly
  • Then the targets carry their requirements around with them
• Helper module is very useful
  • Namespace for extra security…
• Use find_dependency for each external dependency
• Chris G: Are all of the examples written?
  • Ben: Everything bar the Config file template is actually generated by CMake for us. Can write by hand in non-CMake based projects, though need to use correct sequence of commands.
• CMake Summary:
  • Use target properties
  • Be relative to CMAKE_INSTALL_PREFIX
  • Export use-time targets, instead of set_LIBRARIES
  • Refind external targets in the config file, so that things are correctly transitive
• Chris G - this very helpful! How would you encode this into a system like CET buildtools/modules?
  • Replace include directories with target include directories
  • Does require some changes in use by users.
    • Maybe use an alias to a namespace target
  • People have tended to use variables directly, which complicates the issues
• Ben C - can we publish this on the HSF website so we don’t lose it?
  • Should update the HSF tool for bootstrapping projects and include this best practice use of CMake

AOB

• Chris:
  • Will have a SpackDev talk at CHEP - talk will be given by Liz.
  • Setting up a build cache for sci-soft, should be up and running in the next few weeks.
  • Have a PR for spackdev extension, discussions with reviewer ongoing.
  • Upcoming Spack 0.13 release, but concretiser overhaul not ready (which is a big one for us).
  • Have an application in for a person to help.
• Patrick:
  • Have been installing some things on CVMFS at FNAL. Some requests to install OS X binaries on to linux based CVMFS. This is now implemented in Spack!
  • Borrowed the conda routine for patching paths, with same restriction (new path must be shorter than old)
  • See Spack HEP channel for details.

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