How to manage multiple gemsets and ruby versions with RVM?

Question

I am really confused by the explanations given in RVM website. The relation between different ruby interpretors and gemsets are not clear to me. According to me, it is like this -

1. My Account in my Mac have one rvm
2. That rvm installs and manages set of different versions of ruby interpretors.
3. each ruby version has set of gemsets.

Am i getting things clear... Any more amount of explanations are welcome. I am in a position to work on (Ruby 1.8.7 + rails 2.3.8 and its dependencies) and (Ruby 1.9.2 and Rails 3.0 and its dependencies)...

If any one is well versed with handling many ruby versions and gemsets with the help of rvm, please explain to me... thanks for the help

Answer 1

Here is how I like to do it...

1. Install a ruby with RVM
2. Switch to/use that ruby
3. Create a gemset for a project
4. Switch to/use that gemset
5. Install gems needed
6. create an alias that points to my chosen ruby & gemset
7. switch to/use that new alias (again, associated w/ a project)

Do this as many times necessary for your different projects that you want to keep separate from eachother.

Example:

$ rvm install ruby-1.9.2
...
$ rvm list

rvm rubies

=> ree-1.8.7-head [ i386 ]
   ruby-1.9.2-head [ i386 ]
   ruby-1.9.2-preview3 [ i386 ]

$ rvm use ruby-1.9.2-preview3

info: Using ruby 1.9.2 preview3
$  rvm gemset create my_project

info: Gemset 'my_project' created.
rvm gemset use my_project

info: Now using gemset 'my_project'
$ gem install httparty
When you HTTParty, you must party hard!
Successfully installed crack-0.1.8
Successfully installed httparty-0.6.1
2 gems installed
$ rvm alias create my_project ruby-1.9.2-preview3@my_project

info: Creating alias my_project for ruby-1.9.2-preview3@my_project.

info: Recording alias my_project for ruby-1.9.2-preview3@my_project.
$ rvm use my_project

info: Using ruby 1.9.2 preview3 with gemset my_project
$ ....

Now I have an entire environment dedicated to a particular project. This is great because I can experiment with all sorts of different gems/versions without worrying about stomping all over other projects that have very specific requirements.

Good luck!

Answer 2

To add onto Brian's answer above, you can also use .rvmrc files to dynamically switch gemsets when entering new project directories.

simply run the following:

rvm rvmrc create ruby-1.8.7-p358@my_project

This will help stop confusion which I had when switching and forgetting to change gemsets

UPDATE .rvmrc files are in the process of being dropped for the newer .ruby-version file see discussion here: https://gist.github.com/fnichol/1912050