Isolate is a very simple RubyGems sandbox. It provides a way to express and install your code’s Gem dependencies.
When Isolate runs, it uses GEM_HOME, GEM_PATH, and a few other tricks to completely separate your code from the system’s RubyGems configuration, leaving it free to run in blissful solitude.
While Isolate doesn’t make any assumptions about what sort of code you’re writing, it was extracted from a few Rails apps, so it’s naturally going to be most useful with stuff like Rails, Merb, or Sinatra.
Isolate is very, very, very stupid simple. For a much more full-featured Gem bundler, check out Yehuda Katz and Carl Lerche’s Bundler: It does a lot of fancy AOT dependency resolution, supports non-gem resources, and is probably a better fit for you. For a widely used Gem manager and installer, check out Chad Woolley’s GemInstaller.
YMMV, but I haven’t tried Isolate with anything older than RubyGems 1.3.5.
It’s pretty easy: gem
is similar to RubyGems’ method of the same name. Version specifiers are optional, and any hash args tacked on to the end are passed through to Gem::DependencyInstaller as flags.
require "rubygems" require "isolate" Isolate.gems "vendor/isolated" do gem "johnson", "~> 1.1" # or maybe... gem "jbarnette-johnson", :source => "http://gems.github.com" end
At the end of the Isolate.gems
block, you’re completely isolated. GEM_PATH
and GEM_HOME
are set, and all your specified gems have been activated.
Sometimes different sets of gems are appropriate at different times. Isolate allows you to restrict gems by ‘environment’ (which is really just a string passed in when things are activated).
Isolate.gems "vendor/isolated" do gem "intercession" environment :test, :cucumber do gem "mocha" end end
Unsurprisingly, the mocha
gem will only be activated in the test
and cucumber
environments. See the Rails example below for an example of how to use RAILS_ENV
to set your environment.
Isolate.gems "vendor/isolated", :install => true, :verbose => true do gem "intercession" end
Isolate can install your gems automatically. Just pass an :install
option to Isolate.gems
. Pass :verbose
if you want to see what’s going on.
Here’s a quick example (extracted from a real project) of how to use Isolate with Rails. This project doesn’t use vendored Rails, and doesn’t want to depend on any system gems (except isolate, of course).
Gem dependencies are defined in config/preinitializer.rb
. If you want, you could just as easily put them in config/{gems,deps,whatever}.rb
, just make sure it’s loaded in the preinitializer:
require "rubygems" require "isolate" Isolate.gems "vendor/isolated", :install => true, :verbose => true do gem "rails", "= 2.2.2" # async emails! gem "ar_mailer", "~> 1.3", '>= 1.3.3' # Facebook integration gem "facebooker", ">= 1.0.31" # Google contacts integration gem "gmail_contacts", "~> 1.7" # View templates gem "haml", "~> 2.0" # Session as model gem "intercession", "~> 1.0" # XML/HTML parsing in Facebooker and tests gem "nokogiri", ">= 1.2.3" # Twitter authentication gem "oauth", "~> 0.3" environment :development, :test do gem "modelizer" # easy model factories gem "sqlite3-ruby" # database support gem "vlad" # deployment gem "webrat" # integration tests end environment :cucumber do gem "cucumber" # stories! end end
Since this is in the preinitializer, Isolate will install and activate the fundamental gems before Rails loads.
This is early enough in Rails’ lifecycle that RAILS_ENV
isn’t set, so we need a way to activate gems for the current environment. Let’s add one line to config/environment.rb
, right below where boot.rb
is required:
require File.join(File.dirname(__FILE__), 'boot') Isolate.activate RAILS_ENV
Pow. Isolated!
$ gem install isolate
Copyright 2009 John Barnette (jbarnette@rubyforge.org)
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.