Installing Caldecott on Windows

Created November 30, 2012 · Updated June 27, 2026 · 1 min read · 213 words

I wrote this because I received the following error trying to establish a tunnel to a MySQL instance on AppFog:

To use `af tunnel', you must first install Caldecott:

        gem install caldecott

Note that you'll need a C compiler. If you're on OS X, Xcode

will provide one. If you're on Windows, try DevKit.

This manual step will be removed in the future.

Error: Caldecott is not installed.

To solve this problem, follow these steps:

You need a Ruby distribution from rubyinstaller.org for this.
You probably already have that, otherwise go download the newest RubyInstaller from the top of this page.
Download the latest DevKit (Development Kit) from the same page, it is right below the heading “Development Kit”.
Run the DevKit executable (it is just a self-extracting 7Z archive and can be unpacked with other tools, if necessary) and extract it somewhere. Be sure to specify a new or empty directory as the destination.
Rename the directory extracted in the previous step to devkit and move it to your Ruby’s installation folder, e. g. C:\Ruby193.
Open a command prompt as an administrator (e. g. by pressing the Start button, typing cmd, right-clicking the link to the command prompt and choosing “Run as Administrator”).
Change to the devkit folder by typing e. g. cd C:\Ruby194\devkit (depends on your Ruby installation folder of course).
Run the following command:
```
ruby dk.rb init
```
Run the following command:
```
ruby dk.rb install
```
Finally, to install Caldecott, run the following command:
Terminal window
```
gem install caldecott --platform=ruby
```

In case of problems check these instructions on GitHub. Good luck!