How do I freeze gems into Rails application in Rails 3?

Question

I want to freeze a specific gem into my Rails application.

In rails 2 there was this command:

rake gems:unpack

I can't find that command in Rails 3.

Answer 1

I haven't had to do this yet, but I believe it's all handled by bundler.

When you create a new rails3 app, the rails dependencies are put into your Gemfile. You can run bundle install to install them. By default, they are installed into your BUNDLE_PATH.

If you want to install them within your app, you can specify where: bundle install vendor/gems.

Answer 2

Assuming you already have bundler gem installed:

• $ bundle lock
• $ git add Gemfile.lock

Answer 3

So, the short answer is, you don't.

When you modify your Gemfile, and then run bundle install or bundle update, bundler handles the dependency resolution for you and determines the best (newest) versions of each gem you've required that satisfies the entire dependency chain (you won't get a new version that breaks another gem in the dependency list, etc.). You can also of course place a specific version, or a '>= 1.2.3' specification or whathaveyou in the Gemfile using the familiar syntax from the config.gem days, and bundler will make sure to satisfy that as well (or won't produce a Gemfile.lock if there is no valid resolution).

When Bundler does its business, it creates the Gemfile.lock file, which (and this is provided you use bundler alone for managing your gem on all workstations/environments/deployments) performs the same function as freezing all of the gems you've required. For free! (Check this file into version control!) If your new development intern pulls down your source on a fresh machine, it takes one bundle install and the exact same versions of the gems that you have installed are on her machine. Push to deployment, and do a bundle install --deployment there (or more likely, throw it in your Capfile), and the same gems are installed (this time into vendor/bundle, configurable). Bundler is used in Rails 3 to manage loading all of the gems, so wherever you've told bundler to install them (whatever your normal gem install location is by default, or BUNDLE_PATH (which is recorded in .bundle/config if you install with bundle install --path=foo otherwise), bundler will load the right ones, even when they differ from system gems.

You don't need to unpack the gems and check them in to your app, because it doesn't matter: you're guaranteeing the same versions are being called regardless of where they are installed, which will likely vary from machine to machine anyways (.bundle/ should not be checked in to the repo) - so why stick another 60-80 MB of files into your repo that you won't ever be changing or using? (incidentally, this is why I wouldn't recommend a bundle install --path=vendor/gems like nfm suggested - it's not necessarily wrong, there's just no benefit to it over the normal bundler workflow, and now your repo size just ballooned up).