How do you use multiple rails versions with rbenv? - ruby-on-rails

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

Answer 2

There is a rbenv plugin called rbenv-gemset which should behave similar to the rvm gemset-command but since rbenv was never intended to work this way, I haven't tried it.
I usually manage Rails versions with Bundler as Nathan suggested in the comments of one of the other answers. I create a Gemfile with my desired Rails version, run bundle install, create the Rails application, let it replace the Gemfile and let Bundler take over:
mkdir my-rails-app
cd my-rails-app
echo "source 'https://rubygems.org'" > Gemfile
echo "gem 'rails', '3.2.17'" >> Gemfile
bundle install
bundle exec rails new . --force --skip-bundle
bundle update
If you want more detail, I wrote an article on my blog about it.
Hope it helps!

Answer 3

If you have setup ruby using rbenv the following will work.
Installing rails, the latest version (7.x as of Oct 2022)
gem install rails -v 7.0.2.4
# Find exe
rbenv rehash
To create a rails project with the latest rails version,
rails new project_1
This will create a rails application with the latest version, to verify we can see the rails version in the Gemspec file (or) see the logs during the installation,
Installing rails, 6.x.x.x version
Assuming we are going to install rails 6.0.4.8, then issue the following commands
gem install rails -v 6.0.4.8
rbenv rehash
Now, to create a rails project with 6.0.4.8 version (which is installed previously), specify the rails version along with the rails command.
rails _6.0.4.8_ new project_2
This will create a rails application with the 6.x version, to verify we can see the rails version in the Gemspec file (or) see the logs during the installation,
Other notes
Similarly, we can manage any no of rails versions in any number of
projects.
rbenv rehash Installs shims for all Ruby executables known to
rbenv
In this approach, you don't need to set or modify any ruby
environment variables.
You don't need to modify Gemspec file by yourself.
The instructions work as of Oct 2022.