[Nix-dev] Using bundlerEnv to create a rails development environment

[ml+nixos at 6x9.fr]

Hello,

I am trying to use bundlerEnv to create a development environment I'll
use with nix-shell in the context of a rails application.

When I am launching nix-shell, I would like the following to happen:

- having all the needed gems my application depend on installed
- start any dependent services (databases for example) until the shell
  is gone

Currently I have the following `default.nix` in my test dev folder:

-----------------------------------------------------------------------
with (import <nixpkgs> {});

let
   project_name = "myproject";
   ruby = pkgs.ruby_2_2_0;

   env = bundlerEnv {
      name = project_name;

      inherit ruby;
      gemfile = ./Gemfile;
      lockfile = ./Gemfile.lock;
      gemset = ./gemset.nix;
   };
in

stdenv.mkDerivation {
   name = project_name;
   src = null;
   buildInputs = [ env postgresql ];

   shellHook = ''
      set -e;
      export PGDATA="/var/dev-srv/pg-${project_name}"
      export PATH=${env}/bin:$PATH
      export GEM_HOME=${env}/lib

      if [ ! -d $PGDATA ]; then
         initdb
      fi

      if [ $autostart-postgres ]; then
         pg_ctl -D $PGDATA -l ~/code/myproject/log/pg.log start
         trap 'pg_ctl -D $PGDATA stop' EXIT
      fi
   '';
}
-----------------------------------------------------------------------

Which is basically a tentative to smach together multiple stuff I found
for other development environment and bundlerEnv.

This start and stop the postgresql database when I go in nix-shell, but
it does not load all the gems correctly (they are installed, but not all
available to ruby). This is what happen when i call rake in the
nix-shell:

-----------------------------------------------------------------------
Could not find i18n-0.7.0 in any of the sources
Run `bundle install` to install missing gems.
-----------------------------------------------------------------------

Note that I am a total noob when it come to Nix currently, so it does
not surprise me that this is not working!

Can somebody help me on this?

Best regards,

-- 
Mayeu a.k.a Matthieu
http://6x9.fr
GPG: A016 F2D8 0472 1186 1B33  A419 22B1 0496 B00D A693
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