How do you use multiple rails versions with rbenv?

Question

Is it possible to use multiple versions of rails using rbenv (e.g. 2.3 and 3.1)? This was easy with gemsets in rvm, but I'm wondering what the best way is to do it now that I've switched to rbenv (also, I'm looking for a way to do it without rbenv-gemset).

Answer 1

not sure if you got an answer to this, but I thought I'd offer what I did and it seemed to work.

So once you get rbenv installed, and you use it to install a specific ruby version, you can install multiple versions of rails to for that ruby.

STEP 1. Install whatever version(s) of rails you want per ruby version

% RBENV_VERSION=1.9.2-p290 rbenv exec gem install rails --version 3.0.11

By using the "RBENV_VERSION=1.9.2-p290" prefix in your command line, you're specifying which ruby rbenv should be concerned with.

Then following that with the "rbenv exec" command, you can install rails. Just use the version flag as in the example to specify which version you want. Not sure if you can install multiple versions in one shot, but I just run this command as many times as needed to install each version I want.

Note: This will all be managed within your rbenv directory, so it's perfectly safe and contained.

STEP 2. Build a new rails project by specifying the rails version you want.

% RBENV_VERSION=1.9.2-p290 rbenv exec rails _3.0.11_ new my_project

STEP 3. Don't forget to go into that project and set the local rbenv ruby version.

% cd my_project
% rbenv local 1.9.2-p290

---

Now if you want to delete this project, just delete it as normal.

If you want to delete / manage a rails version from rbenv gems, you can use regular gem commands, just prefix your command line with:

% RBENV_VERSION=1.9.2-p290 rbenv exec gem {some command}

And of course, you can delete a complete ruby version and all its shims, etc that are managed within rbenv pretty easily. I like how self contained everything is.

Hope this helps.

For reference, this is a pretty good walk through of at least some of this stuff:

http://ascarter.net/2011/09/25/modern-ruby-development.html