TL;DR Install chef version 11.10.4
Install the Chef gem; ` gem install chef ` . Then try to configure Knife
$ knife configure --initial
> WARNING: No knife configuration file found
> Where should I put the config file? [/Users/ellery/.chef/knife.rb]
> ERROR: Ohai::Exceptions::DependencyNotFound: Can not find a plugin for dependency os
Weird. It seems that Ohai is the problem. Looking at Chef on rubygems, we can see that Chef 11.12.2 depends on Ohai 7.0. However, the Ohai page says that version 6 is the current version before Chef 11.12.0. Now to check if using Ohai 6 will fix the issue.
Back on rubygems, the latest version of Chef that doesn’t need Ohai 7 is Chef 11.10.4. So
gem uninstall chef, remove the executables, and then
gem install chef -v 11.10.4. Once that has run,
knife configure --initial will begin prompting you for the Chef server URL and other settings. In other words, it works!