I came across this as I was trying to install inspec to run against some Packer builds. The Github documentation only covers how to install inspec, and not the pre-requisites.
You likely experienced an error such as “[…] requires installed build tools” and you may try to run gem install buildtools
However, What you need to do is download the Ruby developer kit from https://rubyinstaller.org/downloads/ (found at the bottom of the page). You can unzip this wherever you like (I unzipped it to my Ruby install directory in a folder called devkit). From there, press SHIFT and right click, to open a command prompt window at that location. Now type:
ruby dk.rb init
and
ruby dk.rb install
The full output for these commands is below:
C:\Ruby23\devkit>ruby dk.rb init [INFO] found RubyInstaller v2.3.3 at C:/Ruby23 Initialization complete! Please review and modify the auto-generated 'config.yml' file to ensure it contains the root directories to all of the installed Rubies you want enhanced by the DevKit. C:\Ruby23\devkit>ruby dk.rb install [INFO] Installing 'C:/Ruby23/lib/ruby/site_ruby/2.3.0/rubygems/defaults/operating_system.rb' [INFO] Installing 'C:/Ruby23/lib/ruby/site_ruby/devkit.rb'
Now, you can go ahead and
gem install inspec
Which will begin the installation.