How to tell which version of a gem a rails app is using

Question

I\'m investigating a rails app - the prod server has two version of a specific gem installed, how can I tell which version the prod app is using?

Answer 1

There probably is a more direct way to find this out, but if you load up a console and require a specific version like so:

gem 'RedCloth', '3.0.4'

It will tell you what version is already activated:

=> Gem::LoadError: can't activate RedCloth (= 3.0.4, runtime) for [], already activated RedCloth-4.2.2

Answer 2

Try using script/about. Your config/environment.rb also has information about it.

In your config/environment.rb you can specify which version of a particular gem the application should use. However if you have multiple versions of a gem installed on your machine and you do not specify the version, the latest version of that gem will be used by the application.

Answer 3

In Gemfile , there should be the answer:

gem 'rails', '4.0.0.rc1'