How to deal with different gem dependencies within Bundler for scripts within a single Rails project?

Our Rails application pulls feeds from multiple sources. The workers that pull these feeds need gem dependencies for rmagick, oracle databases, and many other gems. In short, they have very different dependency needs than the main web application. Until Rails 3 and Bundler, life was good.

These worker gem dependencies are irre开发者_JS百科levant to our actual production website. Under Rails 3, one Gemfile is expected to contain all these dependencies. This has the nasty side effect of requiring all gem dependencies to be loaded within the production app, which would cause pointless bloat, possible security issues, memory leaks, complicate deployment, and other ills. Sadly, Bundler breaks the standard require mechanism, which would have provided a way out of the quagmire by allowing us to simply require the necessary gems only in the worker and have them somewhere on the system, not in the bundle. The workers use our rails models to file their data.

Can anyone suggest solutions to make the system practical in Rails 3? I am tempted to make the Gemfile use conditional environment variables in places to drive the gem commands, however, it seems the Gemfile.lock could make this problematic going from working on one worker script (for the feeds) to the next, which would have different dependencies. Help???

I've been contemplating a similar problem, and although I don't have a solution in use anywhere yet, your question did make me think it out some more. I think you should be able to use a group to accomplish this. You can add something like this to your Gemfile:

group :workers do
  gem "extra_gem_1"
  gem "extra_gem_2"
end

Then, you can call

Bundler.require(:default, :workers)

and that should load your gems. How this works will depend on your setup, you might be able to add logic to config/application.rb, or you might need to do this elsewhere. This might be hackish, but it works in the console anyway.

When installing your gems, you can call:

bundle install --without workers

to exclude those gems from production.

Alternatively, you can use two Gemfiles, but that seems like a mess as well since presumably there's some crossover.