[Nix-dev] dead sources

[Mathijs Kwik]

Hi all,

This weekend, I wanted to try out the stdenv-updates branch.
I was prepared for it to take some time to build, as my
build-expression builds everything for all my systems, including a
livecd, and as such it covers quite a lot of dependencies.

But instead of just having to wait for a while, the whole experience
was a lot less pleasant, as the build process errored out every hour
or so, because of missing source downloads. As I was not present the
whole time, but only check/fix/restarted occasionally, I'm not even
halfway done yet :(


I think it's important to be able to build nixos/nixpkgs fully from
source, or at least know upfront if any download-related errors will
occur.
I can think of 3 ways which could improve the current situation.

a) --download-only option for nix-build
That way, before attempting long builds, I can make sure I have all
the sources, and don't even need an internet connection during the
real build.

b) have sources available from nixos.org
This can be in a channel, or some other way. I understand using a
channel would mean these downloads would always be tried on nixos.org
first, while we probably want the original source tried first, so
perhaps fetchurl can be extended to try nixos.org as a last-resort
mirror somehow.

c) have hydra try from-scratch (almost empty store) builds every few
weeks and report to the list so maintainers can fix/look for sources
elsewhere.


Would any of these solutions be easy to implement?
Or are there other options I didn't consider?

Thanks,
Mathijs


PS:
One of the main offenders are the sources for the many versions of iwlwifi.
The official site for these, intellinuxwireless.org is down, and seems
to have been so since july 2010 [1]. I found most of the sources
mirrored elsewhere (mainly fedora), but an overview of all most recent
versions seems lacking.
I haven't investigated the status of this any further, as I don't own
such hardware, but relying on old mirrored copies without active
development will probably hurt some day.

[1] http://wayback.archive.org/web/20110801000000*/http://intellinuxwireless.org