Using Hunspell With Heroku - ruby-on-rails

Question

I'm building a Rails app that uses Hunspell and the hunspell-ffi gem so that Ruby can interface with it. I'm deploying the app to heroku, but unfortunately it needs Hunspell to be installed on the server in order for the gem to work.
Is there any way for me to install Hunspell on Heroku? Or am I going to have to migrate to EC2?
Thanks in advance :)

Answer 1

You need to build the required Hunspell library and include it in your Heroku project directly.
Heroku runs on 64-bit Ubuntu therefore the binary has to be compiled under that system. The best approach is to simply use Heroku's Vulcan build server to compile on a Heroku instance.
Compiling for Heroku
gem install vulcan
vulcan create vulcan-compile-me last argument is your own app name.
Download Hunspell source
Extract
vulcan build -v -s ./hunspell-1.3.2 Tells Vulcan to build it and downloads the finished product automatically to /tmp/hunspell..
The build server requires the cloudant add-on, this is installed automatically but you have to make sure to have a verified (credit card added) Heroku account. If you get errors in step six of no build output then do heroku addons:add cloudant --app vulcan-compile-me
Adding to Your Project
Extract the Heroku Vulcan build tar from /tmp
Copy the entire lib folder to vendor/hunspell in your project root directory
Tell Heroku where to look for libraries: heroku config:add LD_LIBRARY_PATH=vendor/hunspell/lib.
Install Dictionaries
Download some dictionaries from Open Office and add them to your project. A good location is a folder called dictionaries at root level. This path is then referenced when initializing Hunspell in Ruby.
http://extensions.services.openoffice.org/dictionary
ftp://sunsite.informatik.rwth-aachen.de/pub/mirror/OpenOffice/contrib/
Using
Install your favorite Hunspell gem, I use hunspell-ffi. There is a newer gem for Hunspell but I prefer the previous FFI gem. To use initialize the Hunspell object with your dictionaries folder path and language (language match the dictionary file name).
dict = Hunspell.new("dictionaries", "en_US")
if dict.check('caribean') == false
suggestions = dict.suggest('caribean')
if (suggestions.size)
correction = suggestions.first # returns 'caribbean'
end
end
Vendoring for More Complex Projects
You can also vendor the library into your project by putting the tar built by the Vulcan server in the first step into a public accessible server such as Google Storage and then changing the Heroku build pack to download the tar on each instance startup.
heroku config:set BUILDPACK_URL=https://github.com/peterkeen/heroku-buildpack-vendorbinaries.git
The vendor build pack looks for a .vendor_urls file at the root level with HTTP links to the tar balls to install (needs to end in a new line to work).
http://commondatastorage.googleapis.com/developer.you.com/hunspell-heroku-1.3.tgz
Vendoring unpacks the tar into the root folder so the lib path for the Heroku settings would then just be "lib". heroku config:add LD_LIBRARY_PATH=lib

Answer 2

Unless I am mistaken or something has changed (I cannot find any evidence of this), you cannot install external native libraries on Heroku. If the library is not already installed (this is the case, I think, for ImageMagick, and perhaps others), you will not be able to use the gem.

Answer 3

Checkout this url: http://gems-summary.heroku.com/2011-07-19
It's freaking amazing how much support Heroku has for the gem community. So all you need to to is add the gem to your bundle since Hunspell is on rubygems, bundle install, and then deploy.
Gemfile
source 'http://rubygems.org'
gem 'rails', '3.0.5'
gem 'hunspell'
Then add to git:
git add .
git commit -m 'added hunspell'
Then bundle:
bundle
And deploy:
git push heroku

Answer 4

With Bundler, you should be able to install any gem. According to http://devcenter.heroku.com/articles/how-do-i-install-gems-for-my-app, "Almost any gem - even those with native dependencies - can be installed using Bundler. If there’s a specific gem that won’t install on Heroku, please submit a support ticket."
AFAIK, when your app is spun up, gems in the Gemfile are installed on-the-fly to the server your app is spun up to.
The Aspen stack has pre-installed gems, but you still should be able to add gems not pre-installed.
The bamboo stack has no pre-installed gems, so all gem dependencies must be declared explicitly. I believe that is the same for the Celadon stack.