RubyInline in Shared Rails Environments

As an end-to-end web production company, we have a vested interest in making Rails applications easier to deploy for both development and production purposes. We’ve developed Tyrant, a Rails app for running Rails apps, and we’re eagerly watching as new solutions are created and refined.

But it’s a new market, and current solutions are not without their share of obstacles. In working with both Tyrant and Phusion Passenger, we’ve encountered difficulties running applications that use RubyInline to embed C into Ruby code (e.g., ImageScience, my image processing library of choice). Try to start up an app that uses RubyInline code in a shared environment, and you might encounter the following error:

 /Library/Ruby/Gems/1.8/gems/RubyInline-3.6.7/lib/inline.rb:325:in `mkdir': Permission denied - /home/users/www-data/.ruby_inline (Errno::EACCES)

RubyInline uses the home directory of the user who started the server to compile the inline code; problems occur when the current process is owned by a different user. “Simple,” you think. “I’ll just open that directory up to everybody.” Not so fast, hotshot. Try to start the app again, and you get the following:

 /home/users/www-data/.ruby_inline is insecure (40777). It may not be group or world writable. Exiting.

Curses! Fortunately, VigetExtend is here to help. Drop this into your environment-specific config file:

 temp ='ruby_inline', '/tmp') dir = temp.path temp.delete Dir.mkdir(dir, 0755) ENV['INLINEDIR'] = dir 

We use the Tempfile library to generate a guaranteed-unique filename in the /tmp directory, prepended with “ruby_inline.” After storing the filename, we delete the tempfile and create a directory with the proper permissions in its place. We then store the directory path in the INLINEDIR environment variable, so that RubyInline knows to use it to compile.

David is Viget's managing development director. From our Durham, NC, office, he builds high-quality, forward-thinking software for PUMA, the World Wildlife Fund,, and many others.

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