Add a chruby_gem LWRP

[Atalanta]

It would be great to be able to specify gems to install per Ruby:

For example:

chruby_gem "bundler" do
ruby "1.9.3-p429"
end

[Atalanta]

Ignore above comment. That should be for issue #4

Re: LWRP: Postmodern suggests using chruby-exec.

Investigating.

[postmodern]

I would lean towards a bundler style syntax:

chruby '1.9.3' do
  gem 'foo'
end

chruby '1.9.3', 'jruby' do
  gem 'foo'
end

[atalanta-cookbooks]

There's some restriction around the way LWRPs work - the DSL keyword needs to be chruby_something

How about:

chruby_gem '1.9.3' do
  gem 'foo'
end

chruby_gem ['1.9.3', 'ree'] do
  gem 'bar'
end

Easiest to implement would be:

chruby_gem 'rspec' do
  version ['1.9.3', 'jruby']
end

I think this is how the rbenv_gem works.

What do you think?

[postmodern]

I don't know how LWRPs work, but I would favour the least repetitious / "blocky" syntax.

[atalanta-cookbooks]

chruby-exec doesn't quite behave as I expected:

$ chruby
   1.9.3-p392
 * 1.9.3-p429
   embedded

$ chruby-exec 392 -- gem install chess
Fetching: chess-0.0.3.gem (100%)
Building native extensions.  This could take a while...
Successfully installed chess-0.0.3
1 gem installed
Installing ri documentation for chess-0.0.3...
Installing RDoc documentation for chess-0.0.3...

$ gem list

*** LOCAL GEMS ***

bigdecimal (1.1.0)
chess (0.0.3)
io-console (0.3)
json (1.5.5)
minitest (2.5.1)
rake (0.9.2.2)
rdoc (3.9.5)
ubuntu@ip-10-240-109-90:~$ ruby --versio
ruby: invalid option --versio  (-h will show valid options) (RuntimeError)
ubuntu@ip-10-240-109-90:~$ ruby --version
ruby 1.9.3p429 (2013-05-15 revision 40747) [x86_64-linux]

$ chruby embedded
ubuntu@ip-10-240-109-90:~$ gem list

*** LOCAL GEMS ***

bigdecimal (1.1.0)
bundler (1.1.5)
chef (11.4.4)
chess (0.0.3)
erubis (2.7.0)
highline (1.6.18)
io-console (0.3)
ipaddress (0.8.0)
json (1.5.4)
mime-types (1.23)
minitest (2.5.1)
mixlib-authentication (1.3.0)
mixlib-cli (1.3.0)
mixlib-config (1.1.2)
mixlib-log (1.6.0)
mixlib-shellout (1.1.0)
net-ssh (2.6.7)
net-ssh-gateway (1.2.0)
net-ssh-multi (1.2.0, 1.1)
ohai (6.16.0)
rake (0.9.2.2)
rdoc (3.9.4)
rest-client (1.6.7)
ruby-shadow (2.2.0)
systemu (2.5.2)
yajl-ruby (1.1.0)

I would expect chruby-exec 392 to only install the Gem for that Ruby. But it seems that Gem is available to all Rubies? Is this what you would expect? Or have I missed something?

[postmodern]

Actually this is an artifact of how chruby sets GEM_HOME. chruby doesn't take into account RUBY_PATCHLEVEL, in order to allow re-using gems between patch-level upgrades.

[atalanta-cookbooks]

Aha; So embedded Ruby is also 1.9.3; so if I asked ruby_build to install something other than 1.9.3, and then ran chruby_exec somthingelse -- gem install, we'd get the behaviour I expected.

[postmodern]

Correct. GEM_HOME is defined as $HOME/.gem/$RUBY_ENGINE/$RUBY_VERSION.

[Atalanta]

Tested with 2.0.0-p195 - behaves as expected.

Next question is how to call chruby-exec from Chef. Two obvious options:

• bash resource
• execute resource

chruby-exec is actually a Bash function, I guess, so I'll need to source chruby first. Something like:

bash "Install rspec" do
  user "ubuntu"
  code <<-EOH
  source /etc/profile.d/chruby
  chruby-exec 2.0 -- gem install rspec --no-ri --no-rdoc
  EOH
end

[Atalanta]

$ sudo chef-apply chruby_gem.rb
Recipe: (chef-apply cookbook)::(chef-apply recipe)
  * bash[Install rspec] action run
    - execute "bash"  "/tmp/chef-script20130602-28477-anwnhq"
ubuntu@ip-10-240-109-90:/tmp$ ruby --version
ruby 2.0.0p195 (2013-05-14 revision 40734) [x86_64-linux]
ubuntu@ip-10-240-109-90:/tmp$ gem list rspec

*** LOCAL GEMS ***

rspec (2.13.0)
rspec-core (2.13.1)
rspec-expectations (2.13.0)
rspec-mocks (2.13.1)

[Atalanta]

Wonder what the best way to guarantee idempotence is. Best would be to look at the file or directory it creates, which could be calculated.

Alternative would be to run gem list and look for the thing we're trying to install.

Thoughts?

[postmodern]

Current chruby-exec is a shell script that invokes $SHELL -l -i -c. I have plans to rewrite it as a shell function, that way someone doesn't try to run chruby-exec from dash.

[Atalanta]

Aha okay, so I guess I don't need to source chruby in that case. Any thoughts on idempotence?