Development Kit

Lars Kanis edited this page Aug 27, 2017 · 90 revisions

Attention: The following description is valid for RubyInstaller-2.3 and older. Starting with RubyInstaller-2.4 we use MSYS2 as our Development Kit. See also the RubyInstaller-2.4 announcement .

DevKit Overview

The DevKit is a toolkit that makes it easy to build and use native C/C++ extensions such as RDiscount and RedCloth for Ruby on Windows.

Simply download, double-click, choose an installation directory, run the Ruby install helper script, possibly tweak a config.yml file for your system specifics, and you’re ready to start using native Ruby extensions.

Quick start

Download it, run it to extract it somewhere (permanent). Then cd to it, run ruby dk.rb init and ruby dk.rb install to bind it to ruby installations in your path.


Questions from the end user: I downloaded DevKit as exe file, unpacked it. Should I place it to some permanent location and then run installation scripts or I can simply run installation script and then delete the unpacked DevKit folder (in a second case I assume that this script injects DevKit into Ruby installation in some way)? – the answer to this question should be placed in first lines of installation guide as it is very important.

Answer: The file should be in its permanent location before running “ruby dk.rb init”.

DevKit Background

One of the challenges many Ruby on Windows users have is how to easily use native RubyGems from the community such as the rdiscount or curb gems. In many cases this isn’t a problem because the extension author has provided a binary gem compatible with the users Ruby environment. In other cases, only the extension source code is available in the gem and the user is expected to have a “sane” environment installed and configured in order to build and use the native gem. A “sane” environment typically means a system with make, gcc, sh and similar *nix build tools installed.

This expectation of a “sane” build environment is not always true for Windows users and is the primary reason why the DevKit was created. The DevKit, based upon MSYS and MinGW components, is an easy-to-install and easy-to-use solution for quickly setting up a “sane” build environment, enabling you to use most native RubyGems developed by the Ruby community.

We use the DevKit internally for the RubyInstaller project. The DevKit is used to build MRI Ruby and the required dependencies needed to deliver the RubyInstaller for Windows. Many community members also use the DevKit as their “foundation” toolkit for building other native software.

The DevKit is currently available for download as a self-extracting archive and a Windows installer is in development.


  • Windows XP or greater (32 or 64-bit).
  • A Ruby installation from RubyInstaller. This is important as it will not work with any other version of Ruby (e.g. old One-Click)
  • NOTE: The path to your <RUBY_INSTALL_DIR> must not contain any whitespaces (like in “C:\Program Files\Ruby193”). This is very important because whitespaces in the path to your ruby installation will cause certain error messages as soon as you try to install gems which require the DevKit.
  • NOTE: for the legacy RubyInstaller v1.8.6 use the DevKit-3.4.5 available at our archive downloads page. For RubyInstaller versions 1.8.7, 1.9.2, and 1.9.3 use the DevKit 4.5.2 from our main downloads page.

Installation Instructions

While installation is (in general) simple, please ensure you carefully follow each step below.

1. Preparation

  • If you previously installed the legacy DevKit devkit-3.4.5r3-20091110.7z, its artifacts were extracted into each Ruby installation and need to be manually removed. Remove the gcc.bat, make.bat, and sh.bat stub batch files in <RUBY_INSTALL_DIR>\bin and the <RUBY_INSTALL_DIR>\devkit subdirectory for each Ruby installation using the legacy DevKit.
  • If you previously installed one of the legacy self-extracting DevKit’s, follow the SFX DevKit upgrade instructions.

2. Download Files

3. Extract Files

  • Left double-click the self-extracting executable (SFX) downloaded from Step 2 and choose a directory (without spaces) to install the DevKit artifacts into. For example, C:\DevKit. NOTE: the SFX is really a 7-Zip archive with a bit of embedded magic. If you already have 7-Zip installed, you can simply right-click it and extract its contents as you would a normal 7z archive. In the instructions that follow, the directory that you selected is identified as <DEVKIT_INSTALL_DIR>. NOTE: Do not rename this directory because once you install in Step 4 the path is hardcoded into the Ruby installation. If you do need to rename the directory re-run Step 4 with the --force option.

4. Run Installation Scripts

  • cd <DEVKIT_INSTALL_DIR> from Step 3 above.
  • ruby dk.rb init to generate the config.yml file to be used later in this Step. Your installed Rubies will be listed there (only those installed by a RubyInstaller package are detected at present).
  • edit the generated config.yml file to include installed Rubies not automatically discovered or remove Rubies you do not want to use the DevKit with.
  • [optional] ruby dk.rb review to review the list of Rubies to be enhanced to use the DevKit and verify the changes you made to it are correct.
  • finally, ruby dk.rb install to DevKit enhance your installed Rubies. This step installs (or updates) an operating_system.rb file into the relevant directory needed to implement a RubyGems pre_install hook and a devkit.rb helper library file into <RUBY_INSTALL_DIR>\lib\ruby\site_ruby. NOTE: you may need to use the --force option to update (with backup of the originals) the above mentioned files as discussed at the SFX DevKit upgrade FAQ entry.
  • If you use the x64 version of ruby you might get an error saying `Invalid configuration. Please fix ‘config.yml’ and re-run ‘ruby dk.rb install’`. See

5. Test Installation

  • Confirm your Ruby environment is correctly using the DevKit by running gem install json --platform=ruby. JSON should install correctly and you should see with native extensions in the screen messages. Next run ruby -rubygems -e "require 'json'; puts JSON.load('[42]').inspect" to confirm that the json gem is working.


Please refer to Troubleshooting for known issues or RubyInstaller Google Group for further help.

Example Native RubyGem Installations using the DevKit

Once you’ve installed the DevKit you’ll discover there are but a few different types of native installation scenarios to deal with.

  • The Typical Install Scenario – most of the native RubyGems you’re likely to encounter can be installed by running something similar to gem install bson_ext --platform=ruby. It’s crucial that you include the --platform=ruby option to force RubyGems to build the native gem rather than potentially installing an incorrect binary gem.
  • The Manual Install Scenario – sometimes a native RubyGem requires additional artifacts to already exist on your system and be usable. One such gem is curb which requires curl’s native header and library files in order be built and installed. In this scenario you need to tell RubyGems where to find those headers and library files by using a command similar to gem install curb --platform=ruby -- --with-curl-lib="C:/curl/bin" --with-curl-include="C:/curl/include". In addition, the curl library found in the directory specified with --with-curl-lib must be on your PATH for use at runtime by the curb gem.
  • The Hacky Developer Scenario – a developer building native gems wants to be able to quickly test that their extconf.rb file used to create a Makefile for the native library works correctly. To shorten the development cycle, the DevKit enables the developer to run ruby -rdevkit extconf.rb.

Accessing the Full MSys/MinGW Environment

To access all of the MSYS/MinGW tools from a Command Prompt shell, run the devkitvars.bat helper script (lives in <DEVKIT_INSTALL_DIR>) to update the shell’s PATH environment variable. Similarly, if you’re using PowerShell, run the devkitvars.ps1 helper script.

Alternatively, you can load the DevKit Environment programmatically using require "devkit".

Building the DevKit

As the DevKit is a fundamental part of the RubyInstaller build recipes, you can always build your own DevKit by simply:

  1. git clone
  2. cd rubyinstaller
  3. rake devkit sfx=1

Then look in subdirectory, “pkg” for your newly built DevKit.

Next Steps

Now that you’ve installed the DevKit, you should be able to use many of the native C RubyGems without problems.

However, some extensions may require additional header and library files to also be installed, and still other extensions may need additional work done by the authors in order to get them to compile with the MSys/MinGW based DevKit. If you have problems, please drop us a line at our RubyInstaller Google Group