gem_installer.rb

require 'fileutils'
require 'rubygems'
require 'rubygems/gem_runner'
require 'rubygems/exceptions'
require File.expand_path('./logger', __dir__).to_s

ENV['GEM_HOME'] = File.expand_path('gems', __dir__).to_s
FileUtils.mkdir_p(ENV['GEM_HOME'])
ENV['GEM_PATH'] = "#{ENV['GEM_HOME']}:/var/lib/ruby/gems/1.8"
Gem.clear_paths

module GemInstaller
  def install(lib)
    suppress_output do
      return false if `gem list #{lib}`.include?(lib)
      Logger.info("running 'install #{lib} --no-ri --no-rdoc'")
      Gem::GemRunner.new.run(['install', lib, '--no-ri', '--no-rdoc'])
      Logger.info("failed to 'install #{lib} --no-ri --no-rdoc'")
      false
    end
  rescue Gem::SystemExitException
    Logger.info("Successfully Installed #{lib}")
    true
  end

  def reinstall(lib)
    suppress_output do
      return install(lib) unless `gem list #{lib}`.include?(lib)
      Logger.info("Uninstalling #{lib}")
      Gem::GemRunner.new.run(['uninstall', lib, '-a'])
      Logger.info("Failed to uninstall #{lib}")
      install(lib)
    end
  rescue StandardError => exception
    Logger.error("Failure #{exception.message}")
  end

  def suppress_output
    original_stdout, original_stderr = $stdout.clone, $stderr.clone
    $stderr.reopen File.new('/dev/null', 'w')
    $stdout.reopen File.new('/dev/null', 'w')
    yield
  ensure
    $stdout.reopen original_stdout
    $stderr.reopen original_stderr
  end
end