There are two main CI systems on math-comp repo:
- An OPAM based CI using gitlab, configured in
.gitlab-ci.ymland using Docker images from https://hub.docker.com/r/coqorg/coq/ and OPAM packages from https://github.com/coq/opam-coq-archive This CI is outside the scope of the current document. - A Nix based CI based on top of packages of nixpkgs https://github.com/NixOS/nixpkgs and the coq-nix-toolbox https://github.com/coq-community/coq-nix-toolbox This is further document here.
See this great wiki page https://github.com/math-comp/math-comp/wiki/Using-nix for how to install Nix and use it locally to enjoy CI caching and speed up your development process.
You can take example of the files .github/workflows/nix-action-coq-*.yml
For instance, to rerun multinomials for Coq 8.12 :
% nix-build --argstr bundle "coq-8.12" --argstr job multinomialsThe list of bundles can be found in .nix/config.nix.
For simple overlays, it's enough to add a line in the .nix/config.nix file (look for "overlay" there).
For more elaborate overlays (for instance editing package dependencies),
a simple way to test modification of the CI configuration (new version
or configuration change of some package for instance) is through
overlays, see the corresponding paragraph at
https://github.com/coq-community/coq-nix-toolbox#overlays (for sha256
hashes, one can just put an empty string, run the nix-build command
above and an error will give the correct value).
Once overlays are satisfactory, they should eventually be merged into the nixpkgs package repository.
The file .nix/coq-nix-toolbox.nix contains the git commit hash of
the version of coq-nix-toolbox used (c.f.,
https://github.com/coq-community/coq-nix-toolbox ). Coq-nix-toolbox
itself contains the git commit hash of the version of nixpkgs it uses
(c.f. https://github.com/NixOS/nixpkgs/ ). So in order to add or
remove a Nix derivation (package), one needs to first update nixpkgs,
then coq-nix-toolbox and finally the .nix/coq-nix-toolbox.nix file
here. See the coq-nix-toolbox README
for details of the process.
Basic concepts of the Nix package manager: https://nixos.org/manual/nix/stable/ (I particularly recommend Part I. introduction and Chapter 9. Basic Package Management)
Nix is based on its own functional language: Part IV. Writing Nix Expressions
Specifics for Coq packages: 15.5. Coq and coq packages
The CI uses caching provided by https://www.cachix.org/ and there is a token in the math-comp organization to authenticate and store the results. Any CI build is stored globally and can be used on one's own computer as described in https://github.com/math-comp/math-comp/wiki/Using-nix