[Nix-dev] Using nix under debian stable

[Pjotr Prins]

On Tue, Oct 28, 2008 at 04:21:45PM +0100, Benjamin Franksen wrote:
> I am trying to evaluate using nix as deployment system on top of debian
> gnu/linux for software we write for in-house use. Unfortunately I cannot
> use /nix as the nix store path because I don't have root permissions on the
> relevant machine(s). I could get our admin to create me a symlink /nix to
> somewhere but giving me a 'real' directory (which probably means a
> dedicated partition) would require lots of arguing. So that means I cannot
> use pre-built binaries which makes things a bit slow... Since this is a
> test/evaluation system only, wouldn't it make sense to relax the strict
> no-symlink policy in such cases? It would be ideal if I could configure
> this somewhere when building nix from source. I am willing to patch the nix
> sources if someone could give me a hint where this check is implemented.

Ask him to make a hard link. You can also do away with the
pre-compiled packages. I find it is no problem and you can share
precompiled binaries with other systems as long as the path is the
same. BTW current server farm pre-compiled packages are useless if you
are compiling against other kernel headers (like I do).

> Another question w.r.t. to the nixpkgs (I am using the the current version
> form the svn repo): I noticed that the first time I 'nix-env -i
> some-package' nix downloads and installs linux kernel headers. Now, what it
> installs is version 2.6.23.16, but the kernel my stuff will run under is
> 2.6.18. I am not sure but I think this is potentially unsafe; hence I have
> changed my nix expression to use the same kernel version as I have in my
> host system. This doesn't make a great difference to me at the moment
> because I have to compile everything from source anyway (see above) but it
> could make one in the future so I am asking for your opinion on this.

Add the following to ~/.nixpkgs/config.nix:

{
  git = { svnSupport = true; guiSupport = true; }; # example
  subversion = { perlBindings = true; };

  packageOverrides = pkgs : { 
    kernelHeaders = pkgs.kernelHeaders_2_6_18; 
  };
}

or similar. I also use Debian stable nix-env (Nix) 0.12pre12824.
There is a problem compiling Nix on Debian with regard to a MAXINT -
the gcc compiler may balk. See the fix in a posting earlier
today.

> Yet another thought that occurred to me is: what if I forget about nixpkgs
> and use nix /only/ for our own stuff. Can I write my own nix expression and
> import the OS stuff (compiler tool chain, headers, etc) from outside of the
> nix store? This would be very 'impure' of course, and would limit
> reproducability on other machines, but it might be easier to start
> experimenting with. Any opinions, warnings, hints?

Not easier and fraud with problems. Besides no one else benefits from your
work. Checkout the package tree with svn into 'path' and add your stuff by
compiling:

  nix-env -f path -i mypackage

It will lead to a rock-solid setup. I use Debian stable as a platform. All the
regular tools I have in Nix now.

Pj.