tree 5747b52eb7b24aad7ace513ff930a4526aae1dda
parent 6abe4fa771fc5a47809ad844807dcdcda9219af3
author Serge Bazanski <q3k@hackerspace.pl> 1601065457 +0000
committer Serge Bazanski <q3k@hackerspace.pl> 1601742698 +0200

WORKSPACE: use nix for python/go if available

This introduces Nix, the package manager, and nixpkgs, the package
collection, into hscloud's bazel build machinery.

There are two reasons behind this:

 - on NixOS, it's painful or at least very difficult to run hscloud out
   of the box. Especially with rules_go, that download a blob from the
   Internet to get a Go toolchain, it just fails outright. This solves
   this and allows hscloud to be used on NixOS.

 - on non-NixOS platforms that still might have access to Nix this
   allows to somewhat hermeticize the build. Notably, Python now comes
   from nixpkgs, and is fabricobbled in a way that makes pip3_import
   use Nix system dependencies for ncurses and libpq.

This has been tested to run ci_presubmit on NixOS 20.09pre and Gentoo
~amd64.

Change-Id: Ic16e4827cb52a05aea0df0eed84d80c5e9ae0e07