Reproducible environments

[Konrad Hinsen]

Hi everyone,

I am exploring the use of Guix for reproducible environments in scientific 
computing. My goals are very similar to those described in the paper 
"Reproducible and User-Controlled Software Environments in HPC with Guix".

Section 4.1 of that paper says that a given environment, defined by a Guix 
profile, can be reproduced given (1) a manifest and (2) the Guix commit 
defining all the packages.

Problem #1: After reading the manual twice, I still don't see how I can tell 
"guix package" to use a given Guix commit.

Problem #2: What if my profile contains packages from several Guix commits 
(typically for getting specific older versions)? Or if it contains packages 
defined outside of the Guix distribution, in Guile modules on GUIX_PACKAGE_PATH?

If my understanding of Guix is correct, all the required information for 
rebuilding everything identically is available at a lower level, in the 
derivation files. Would it be feasible to collect all the derivation files 
underlying a profile in a tar archive, and then have them rebuilt and added to 
a fresh profile in an automatized way?

Konrad.