How can I use rdiscount on Heroku?

Question

I am trying to push a small test app to Heroku. Here is the App and the Gem file:

App:

require 'sinatra'
require 'haml'
require 'rdiscount'

set :markdown, :layout_engine => :haml, :layout => :layout


get '/' do 
  haml :index
end

get '/blog' do 
  markdown :test
end

Gemfile:

source :rubygems
gem 'sinatra'
gem 'thin'
gem 'haml'
gem 'rdiscount'

Before pushing to Heroku I run bundle install. But pushing to Heroku fails when trying to install the rdiscount gem:

-----> Ruby/Rack app detected
-----> Installing dependencies using Bundler version 1.3.0.pre.5
   Running: bundle install --without development:test --path vendor/bundle --binstubs   vendor/bundle/bin --deployment
   Fetching gem metadata from http://rubygems.org/..........
   Fetching gem metadata from http://rubygems.org/..
   Using daemons (1.1.9)
   Using eventmachine (1.0.0)
   Using haml (3.1.7)
   Using rack (1.4.3)
   Using rack-protection (1.3.2)
   installing rdiscount (2.0.7)
   Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
   /usr/local/bin/ruby extconf.rb
   checking for random()... yes
   checking for srandom()... yes
   checking for rand()... yes
   checking for srand()... yes
   checking size of unsigned long... long
   checking size of unsigned int... int
   no int with size 4
   *** extconf.rb failed ***
   Could not create Makefile due to some reason, probably lack of
   necessary libraries and/or headers.  Check the mkmf.log file for more
   details.  You may need configuration options.
   Provided configuration options:
   --with-opt-dir
   --without-opt-dir
   --with-opt-include
   --without-opt-include=${opt-dir}/include
   --with-opt-lib
   --without-opt-lib=${opt-dir}/lib
   --with-make-prog
   --without-make-prog
   --srcdir=.
   --curdir
   --ruby=/usr/local/bin/ruby
   --with-rdiscount-dir
   --without-rdiscount-dir
   --with-rdiscount-include
   --without-rdiscount-include=${rdiscount-dir}/include
   --with-rdiscount-lib
   --without-rdiscount-lib=${rdiscount-dir}/lib
   Gem files will remain installed in /tmp/build_3aijv3ga0dy1y/vendor/bundle/ruby/1.9.1/gems/rdiscount-2.0.7 for inspection.
   Results logged to /tmp/build_3aijv3ga0dy1y/vendor/bundle/ruby/1.9.1/gems/rdiscount-2.0.7/ext/gem_make.out
   An error occurred while installing rdiscount (2.0.7), and Bundler cannot continue.
   Make sure that `gem install rdiscount -v '2.0.7'` succeeds before bundling.
 !
 !     Failed to install gems via Bundler.
 !
 !     Heroku push rejected, failed to compile Ruby/rack app

I do understand that rdiscount might depend on some other Gems or libraries and this dependency does not seem to be resolved. However, I do not understand how to solve this problem. Could you give me some advice on how to get this to work?

Answer 1

There seems to be an issue with Ruby 1.9.2 on Heroku and how may bytes it thinks int is.

Try to add ruby "1.9.3" to you Gemfile like this:

source :rubygems
ruby "1.9.3"

gem 'sinatra'
gem 'thin'
gem 'haml'
gem 'rdiscount'

My own testing reproduced your error on 1.9.2 and succeeded on 1.9.3