nixpkgs/doc/languages-frameworks/ruby.xml
2017-07-05 09:12:03 -07:00

99 lines
3.9 KiB
XML

<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)/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>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;
};
}]]>
<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>Resulting derivations for both builders also have two helpful attributes, <literal>env</literal> and <literal>wrapper</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.wrapper ];
script = ./my-script.rb;
buildCommand = ''
mkdir -p $out/bin
install -D -m755 $script $out/bin/my-script
patchShebangs $out/bin/my-script
'';
}]]>
</programlisting>
</section>