Add 'nixpkgs/' from commit '2436c27541b2f52deea3a4c1691216a02152e729'

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diff --git a/nixpkgs/doc/languages-frameworks/ruby.xml b/nixpkgs/doc/languages-frameworks/ruby.xml
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+<section xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xml:id="sec-language-ruby">
+ <title>Ruby</title>
+
+ <para>
+  There currently is support to bundle applications that are packaged as Ruby gems. The utility "bundix" allows you to write a <filename>Gemfile</filename>, let bundler create a <filename>Gemfile.lock</filename>, and then convert this into a nix expression that contains all Gem dependencies automatically.
+ </para>
+
+ <para>
+  For example, to package sensu, we did:
+ </para>
+
+<screen>
+<![CDATA[$ cd pkgs/servers/monitoring
+$ mkdir sensu
+$ cd sensu
+$ cat > Gemfile
+source 'https://rubygems.org'
+gem 'sensu'
+$ $(nix-build '<nixpkgs>' -A bundix --no-out-link)/bin/bundix --magic
+$ cat > default.nix
+{ lib, bundlerEnv, ruby }:
+
+bundlerEnv rec {
+  name = "sensu-${version}";
+
+  version = (import gemset).sensu.version;
+  inherit ruby;
+  # expects Gemfile, Gemfile.lock and gemset.nix in the same directory
+  gemdir = ./.;
+
+  meta = with lib; {
+    description = "A monitoring framework that aims to be simple, malleable, and scalable";
+    homepage    = http://sensuapp.org/;
+    license     = with licenses; mit;
+    maintainers = with maintainers; [ theuni ];
+    platforms   = platforms.unix;
+  };
+}]]>
+</screen>
+
+ <para>
+  Please check in the <filename>Gemfile</filename>, <filename>Gemfile.lock</filename> and the <filename>gemset.nix</filename> so future updates can be run easily.
+ </para>
+
+ <para>
+  Updating Ruby packages can then be done like this:
+ </para>
+
+<screen>
+<![CDATA[$ cd pkgs/servers/monitoring/sensu
+$ nix-shell -p bundler --run 'bundle lock --update'
+$ nix-shell -p bundix --run 'bundix'
+]]>
+</screen>
+
+ <para>
+  For tools written in Ruby - i.e. where the desire is to install a package and then execute e.g. <command>rake</command> at the command line, there is an alternative builder called <literal>bundlerApp</literal>. Set up the <filename>gemset.nix</filename> the same way, and then, for example:
+ </para>
+
+<screen>
+<![CDATA[{ lib, bundlerApp }:
+
+bundlerApp {
+  pname = "corundum";
+  gemdir = ./.;
+  exes = [ "corundum-skel" ];
+
+  meta = with lib; {
+    description = "Tool and libraries for maintaining Ruby gems.";
+    homepage    = https://github.com/nyarly/corundum;
+    license     = licenses.mit;
+    maintainers = [ maintainers.nyarly ];
+    platforms   = platforms.unix;
+  };
+}]]>
+</screen>
+
+ <para>
+  The chief advantage of <literal>bundlerApp</literal> over <literal>bundlerEnv</literal> is the executables introduced in the environment are precisely those selected in the <literal>exes</literal> list, as opposed to <literal>bundlerEnv</literal> which adds all the executables made available by gems in the gemset, which can mean e.g. <command>rspec</command> or <command>rake</command> in unpredictable versions available from various packages.
+ </para>
+
+ <para>
+  Resulting derivations for both builders also have two helpful attributes, <literal>env</literal> and <literal>wrappedRuby</literal>. The first one allows one to quickly drop into <command>nix-shell</command> with the specified environment present. E.g. <command>nix-shell -A sensu.env</command> would give you an environment with Ruby preset so it has all the libraries necessary for <literal>sensu</literal> in its paths. The second one can be used to make derivations from custom Ruby scripts which have <filename>Gemfile</filename>s with their dependencies specified. It is a derivation with <command>ruby</command> wrapped so it can find all the needed dependencies. For example, to make a derivation <literal>my-script</literal> for a <filename>my-script.rb</filename> (which should be placed in <filename>bin</filename>) you should run <command>bundix</command> as specified above and then use <literal>bundlerEnv</literal> like this:
+ </para>
+
+<programlisting>
+<![CDATA[let env = bundlerEnv {
+  name = "my-script-env";
+
+  inherit ruby;
+  gemfile = ./Gemfile;
+  lockfile = ./Gemfile.lock;
+  gemset = ./gemset.nix;
+};
+
+in stdenv.mkDerivation {
+  name = "my-script";
+  buildInputs = [ env.wrappedRuby ];
+  script = ./my-script.rb;
+  buildCommand = ''
+    install -D -m755 $script $out/bin/my-script
+    patchShebangs $out/bin/my-script
+  '';
+}]]>
+</programlisting>
+</section>