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A virtual machine for using rake-compiler
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A virtual machine for using rake-compiler.

rake-compiler is totally awesome, and you should be using it if you maintain a Ruby gem with C or Java extensions to build native binaries for your users.

However, getting your local environment set up to build for all the assorted platforms can be a pain. Thankfully, we have the amazing tool Vagrant for "lightweight, reproducible, and portable development environments."

rake-compiler + Vagrant = easy native gems for all.


How to Build the Virtual Machine


$ git clone
$ cd rake-compiler-dev-box
$ vagrant up

That's it! Go grab a cup of coffee, though -- it can take a couple of minutes to build the first time.

Building Your Native Gems

Once you have your gem ready to package, clone or move your repo into the same directory as the rake-compiler-dev-box:

$ pwd
$ git clone
Cloning into 'bcrypt-ruby'...
[...], done.

Now fire up your virtual machine (if you haven't already):

$ vagrant up

And SSH in:

$ vagrant ssh

You'll now be inside the virtual machine. The directory on your host machine with your gem in it and the scripts to build it will be mounted at /vagrant:

vagrant@precise64:~$ cd /vagrant
vagrant@precise64:/vagrant$ ls
bcrypt-ruby  bin  LICENSE.txt  sample_gem  Vagrantfile

To build all gem binaries (native, Java, and Windows versions), run:

vagrant@precise64:/vagrant$ package_all YOUR_GEM'S_DIR_NAME

And wait for everything to build. Replace YOUR_GEM'S_DIR_NAME with the correct value -- above, it would be bcrypt-ruby. There's a sample_gem dir in there as well if you'd like to experiment.

All of your gem binaries will be put into pkg:

vagrant@precise64:/vagrant$ ls bcrypt-ruby/pkg/
bcrypt-ruby-3.1.0            bcrypt-ruby-3.1.0-x86-linux.gem
bcrypt-ruby-3.1.0.gem        bcrypt-ruby-3.1.0-x86-mingw32
bcrypt-ruby-3.1.0-java       bcrypt-ruby-3.1.0-x86-mingw32.gem
bcrypt-ruby-3.1.0-java.gem   bcrypt-ruby-3.1.0-x86-mswin32-60
bcrypt-ruby-3.1.0-x86-linux  bcrypt-ruby-3.1.0-x86-mswin32-60.gem

Happy compiling!

Limiting Target Rubies

Some gems might choose not to support older versions of Ruby (like Nokogiri, which no longer supports 1.8).

If you wish to limit the versions of Ruby that your cross-compiled Windows binaries supports, you can use the environment variables BASE_VERSION and RUBY_CC_VERSION:

  • BASE_VERSION: the native version of Ruby that will be used as a base for cross-compilation

  • RUBY_CC_VERSION: a colon-separated list of target versions for cross-compilation

Note: If you wish to target 1.8.x, your base version must be 1.8.x -- versions 1.9+ cannot cross-build 1.8.


Use Ruby 1.9.3 to cross-compile a fat binary that includes 1.9 and 2.0 binaries:

vagrant@precise64:/vagrant$ BASE_VERSION=1.9.3 RUBY_CC_VERSION=1.9.3:2.0.0 package_all nokogiri

Use Ruby 2.0.0 to cross-compile a fat binary that includes 2.0 and 2.1 binaries:

vagrant@precise64:/vagrant$ BASE_VERSION=2.0.0 RUBY_CC_VERSION=2.0.0:2.1.3 package_all nokogiri

By default, with no environment variables, rake-compiler-dev-box will try to cross-compile for all available versions, using 1.8 as a base.

VM Management

Log out of the virtual machine (exit or ^D).

To shut down the virtual machine:

$ vagrant halt

To start it up again:

$ vagrant up

To completely remove the VM, clearing it from disk and destroying all contents:

$ vagrant destroy

To reinstantiate it for future compiling, it can be recreated with:

$ vagrant up

See the Vagrant docs for more info.

❤️ ❤️ ❤️

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