Nix From The Dark Ages: Without Root

Academic Clusters

Why?

Where’s Nix?

• Nix is the solution [dolstraNixSafePolicyFree2004]
  • Used by some scientific software too [goswamiDSEAMSDeferredStructural2020]

Does no one use it then?

• Some clusters have nix support

• They actually support it though
• GRICAD has [bzeznikNixHPCPackage2017]
• The Flatiron Institute and Compute Canada also support nix

• What if no-one cared?

• Then you end up here (post)

Methodology Review

Acknowledgements

Who worked on it first?

• jefdaj/nix-no-root
  • Built upto 2.0.4 apparently
• pjotrp/nix-no-root
  • Seemingly abandoned after 2015

What went wrong?

• Massive waste of resources
  • Though they can be traced to the user
• Effectively builds on the login node (~ 3 hours)
  • Can’t be helped without integration with a queue

Better Permission Handling

• e.g. building ruby involves:

watch -n1 -x chmod 777 -R /tmp/nix-build-ruby-2.6.6.drv-0/source/lib/

• Less gratuitous permissions might be set

Better NFS Locks

• Maybe even build in a temporary directory until the lock is released
  • Currently one of the “fixes” includes:

nix-build
# something about a .nfs lockfile in some .nix/$HASH-pkg/.nfs0234234
mv .nix/$HASH-pkg/ .diePKGs/
nix-build # profit

Bills and Queues

Union Mount

• Proposed here
  • by catern
• Would reduce compilation
• Currently does not actually replace the global store
  • Discussion here

Personal Goals

• Native file path test
  • Hash relative to a prefix
• Cleaner Setup
  • Maybe a derivation
• Return Next Year!
  • Hopefully with cleaner methods

Bibliography

• [bzeznikNixHPCPackage2017] Bzeznik, Henriot, Reis, Richard & Tavard, Nix as HPC Package Management System, 1-6, in in: Proceedings of the Fourth International Workshop on HPC User Support Tools - HUST'17, edited by ACM Press
• [dolstraNixSafePolicyFree2004] Dolstra, de Jonge & Visser, Nix: A Safe and Policy-Free System for Software Deployment, , 15 .
• [goswamiDSEAMSDeferredStructural2020] Goswami, Goswami & Singh, D-SEAMS: Deferred Structural Elucidation Analysis for Molecular Simulations, Journal of Chemical Information and Modeling, 60(4), 2169-2177 . doi.