[Nix-dev] dead sources

[Mathijs Kwik]

On Sun, Jan 6, 2013 at 6:10 PM, Michael Raskin <7c6f434c at mail.ru> wrote:
>>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 guess specifying -k (--keep-going) flag to nix-build would help.
>
> nix-build /etc/nixos/nixos -k -A system

Didn't think of that, but it might indeed get me a bit further.
Depends a bit on how high/low in the dependency-tree the missing
source sits though.
For example if some X11 source is not found, building anything
graphical will be skipped.

>
>>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.
>
> I am not sure how the flags get passed around inside...
>
> Right now you could use nix-reduce-build script inside nix repository...
> Among its functionality is
>
> nix-reduce-build /etc/nixos/nixos:-A:system -- nix-self-fixed://
>
> It is not installed by default because it can do so many things that its
> precise purpose is unclear.

Didn't know about it. Looks like a useful tool :)

>
> It looks like NixOS system refers to some downloads that are not needed
> even when building from near-scratch (and so some failures from
> nix-reduce-build are not significant), but it keeps trying the remaining
> things on single failures so it downloads whatever it is possible.
>
>
>