rbenv: multiple instances of SAME ruby

Question

I have two scripts which require the same version of Ruby. However, each script also requires a DIFFERENT version of a gem (nokogiri). One of the scripts will run with both versions of nokogiri (1.6.2.1 and 1.6.1). However the other script will ONLY run with version 1.6.1; and if 1.6.2.1 is installed, the script will not execute normally.

I know how to install multiple versions of Ruby with rbenv. But is it possible to install multiple instances of the SAME version of Ruby (2.1.2)? If so, how?

Answer 1

Make a local copy of a ruby-installer definition file using a custom name.

$ cp ~/.rbenv/plugins/ruby-build/share/ruby-build/2.1.5 2.1.5-nokogiri161

Install this as a custom definition file, no edits required.

$ rbenv install ./2.1.5-nokogiri161

Now you have a ruby version with a custom name and you can install custom gems on it.

$ rbenv shell 2.1.5-nokogiri161
$ gem install nokogiri -v 1.6.1

This is also useful for installing ruby versions with custom build flags. For example, a debug build with no compiler optimizations.

$ cp ~/.rbenv/plugins/ruby-build/share/ruby-build/2.1.5 2.1.5-debug
$ RUBY_CONFIGURE_OPTS="optflags=-O0" rbenv install ./2.1.5-debug
$ rbenv shell 2.1.5-debug

Answer 2

I see two options:

1. You could have different Gemfiles and let bundler take care of setting the right gem-version. If the scripts are in different directories, it should be no problem.

2. You could use rbenv-gemset to have separate gem-environments

There are undoubtly more, but those two seem the easiest for your setup.