Install vagrant-berkshelf (and berkshelf) from their git repositories

README.md

IMHO the correct way to install bleeding edge plugins to Vagrant is to use the standard Vagrant installer.

These instructions should work for Vagrant 1.1.0 - 1.4.x (but probably not for Vagrant 1.5+),

git clone https://github.com/berkshelf/berkshelf.git
cd berkshelf
gem build berkshelf.gemspec

# Install directly to Vagrant's gem storage, as this is not a plugin
gem install berkshelf-*.gem --conservative --no-ri --no-rdoc --install-dir $HOME/.vagrant.d/gems

cd ..

git clone https://github.com/berkshelf/vagrant-berkshelf.git
cd vagrant-berkshelf
gem build vagrant-berkshelf.gemspec

# Normal install with Vagrant
vagrant plugin install vagrant-berkshelf-*.gem

In above commands it's possible to also use Vagrant's embedded gem:

• Linux: /opt/vagrant/embedded/bin/gem
• OS X: /Applications/Vagrant/embedded/bin/gem
• Windows: C:\HashiCorp\Vagrant\embedded\bin\gem

If you need to start fresh after messing with plugins installation, simply delete the content of ~/.vagrant.d/gems directory and ~/.vagrant.d/plugins.json as well and start fresh :)