[rails3]
name=rails3
baseurl=http://tuxdna.fedorapeople.org/packaging/rubygems/f16/
enabled=1
gpgcheck=0

Now when I installed Rails 3.1.0, I got into a in issue:

$ sudo yum install rubygem-rails-3.1.0
...OUTPUT SKIPPED...
--> Running transaction check
---> Package rubygem-polyglot.noarch 0:0.3.3-1.fc16 will be installed
---> Package rubygem-sprockets.noarch 0:2.0.3-1.fc16 will be installed
--> Processing Dependency: rubygem(tilt) < 1.3.0 for package: rubygem-sprockets-2.0.3-1.fc16.noarch
--> Finished Dependency Resolution
Error: Package: rubygem-sprockets-2.0.3-1.fc16.noarch (psb)
           Requires: rubygem(tilt) < 1.3.0
           Installed: rubygem-tilt-1.3.3-1.fc16.noarch (@psb)
               rubygem(tilt) = 1.3.3
           Available: rubygem-tilt-1.3.2-1.fc16.noarch (fedora)
               rubygem(tilt) = 1.3.2
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest

On the surface it seems that rubygem-sprockets wants rubygem-tilt with a version less than 1.3.0 ( we have only 1.3.3 and 1.3.2 available here). However rubygem-sprockets also accepts rubygem-tilt with a version greater than 1.3.0, which is evident from the dependency list:

$ sudo yum deplist rubygem-sprockets-2.0.3-1.fc16.noarch 
Loaded plugins: auto-update-debuginfo, langpacks, presto, refresh-packagekit
Finding dependencies: 
package: rubygem-sprockets.noarch 2.0.3-1.fc16
...OUTPUT SKIPPED...
  dependency: rubygem(tilt) >= 1.1
   provider: rubygem-tilt.noarch 1.3.3-1.fc16
  dependency: rubygem(tilt) > 1.3.0
   provider: rubygem-tilt.noarch 1.3.3-1.fc16
  dependency: rubygem(tilt) < 1.3.0
   Unsatisfied dependency
  dependency: rubygem(tilt) < 2
   provider: rubygem-tilt.noarch 1.3.3-1.fc16

To verify that it is actually a problem specific to RPM, I downloaded the RPMs and tried installing with rpm command rather than yum:

$ yumdownloader rubygem-tilt-1.3.3-1.fc16.noarch
$ yumdownloader rubygem-sprockets-2.0.3-1.fc16.noarch
$ ls
rubygem-sprockets-2.0.3-1.fc16.noarch.rpm  rubygem-tilt-1.3.3-1.fc16.noarch.rpm
$ sudo rpm -i rubygem-sprockets-2.0.3-1.fc16.noarch.rpm 
error: Failed dependencies:
	rubygem(hike) >= 1.2 is needed by rubygem-sprockets-2.0.3-1.fc16.noarch
	rubygem(hike) < 2 is needed by rubygem-sprockets-2.0.3-1.fc16.noarch
	rubygem(tilt) < 1.3.0 is needed by rubygem-sprockets-2.0.3-1.fc16.noarch

Cleary RPM doesn’t handle package version intervals well even though the information is available inside the package – rubygem-sprockets requires

rubygem-tilt: >= 1.1, < 1.3.0, > 1.3.0, < 2.0.0

I have RPM version 4.9.1.2 running on Linux 3.2.7-1.fc16.x86_64.

Same arguments apply to Ruby Gems as well. That is to say, Ruby Gems already have a gem command to install and update packages. However it is still not a complete packaging system in itself.

Consider the situation where you need to install a gem called A which dependes on B and C. So you will do:

gem install A

Problem 1: Handling of install failure

This would obviously install the gems in this order B, C and A. It does works for mostly perfect situations. However if C fails to install, “gem” won’t rollback ( i.e. uninstall B ) any steps till C’s failure. This is a problem.

Problem 2: Creating RPM packages with ease

If you ever happen to use Python’s distutils, you will find that it has ability to generate RPM packages from the setup.py itself. Which means an even wider adoption of Python packages.

python setup.py bdist_rpm

What takes for “gem” to support such a functionality? Since creating, installing, packaging and distributing Ruby gems is such a common activity for Ruby developers, I believe such should be available within the standard Ruby distribution.

For now I am using gem2rpm gem which requires a lot of manual intervention. Here is how it works ( as in my earlier post ):


gem fetch rubygem-my-favorite
gem2rpm -s rubygem-my-favorite.gem


Checkout its documentation for more details.

sudo yum install rubygem-rvm
rvm-install

To include RVM into your bash shell, add following line to ~/.bashrc:

[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm" # This loads RVM into a shell session.

Now install JRuby and use it as default Ruby interpreter:

source ~/.bashrc
rvm install jruby-1.5.6
rvm use jruby-1.5.6

Setup Rails environment:

gem install rails
gem install bundler

Lets create a new Rails application:

rails new rails-app
cd rails-app
bundle install
rails g scaffold Person name:string
rake db:migrate
rails s

Now go to http://localhost:3000/people/
Yay! Your new Rails application is up and running, powered by JRuby ( setup using RVM ).