Getting Chef + RVM playing nicely together

I know that all of maybe 3 people read this blog. I typically forget about it myself. But, I wanted to jot this down someplace, and here seemed as good as any.

We've recently started to move into the world of Rails. We use Chef to manage our infrastructure. There are some quirks to getting them all lined up right, and finding a straight up tutorial is surprisingly tricky. So, here goes:

• Install Chef via Omnibus as recommended by them.
• Get the RVM cookbook, maintained by fnichol.
• Pick a non-root user to run your rails app(s) as. 
• Install RVM/Ruby as that user, via the user recipe in the cookbook.

Any place in your other cookbooks that you are going to call ruby scripts (bundle install, rake db migrate, etc...):

• include rvm::default
• wrap the commands with the rvm_shell LWRP from the rvm cookbook. This ensures that the user's rvm environment is inherited properly. 

Here's an example of the recipe I'm using to install RVM:

node.normal['rvm']['user_installs'] = [
    {
        'user'  => node['fleet']['systemuser'],
        'default_ruby' => node['rvm']['default_ruby'],
        'global_gems' => [
            { 'name'    => 'bundler' },
            { 'name'    => 'rake' }
        ]
    }
] 

include_recipe "rvm::user"

I'm using normal for the attributes to ensure that the defaults in the rvm cookbook are overridden. In my case node['fleet']['systemuser'] and node['rvm']['default_ruby'] are defined elsewhere in the run list.


Then some code (bundle install)

include_recipe 'rvm::default'

rvm_shell "Running Bundle install" do
  user node['fleet']['systemuser']
  group node['fleet']['systemgroup']
  ruby_string node['rvm']['default_ruby']
  cwd node['app']['dir']['deploy']
  environment 'RAILS_ENV' => node['app']['rails_env']
  code %{bundle install}
end

 Again, some attributes are defined elsewhere, but you should be able to get the idea.

This may not be perfect, but it works for me!

Other gotchas:

If you try to install RVM system-wide, chef-client gets sad. You end up changing the environment such that the omnibus ruby is no longer what env ruby finds, so you end up needing to install chef gems into your RVM ruby.

Ugly!

Chef-client always runs as root, and your app should never run as root. So, there shouldn't really be any conflicts here.