Vagrant provisioner of Fabric.

fabric.rb

module Vagrant
  module Provisioners
    class Fabric < Base
      class Config < Vagrant::Config::Base
        attr_accessor :fabfile_path
        attr_accessor :fabric_path
        attr_accessor :python_path
        attr_writer :tasks

        def _default_fabfile_path
          File.exist?("fabfile.py") ? "fabfile.py" : "fabfile/__init__.py"
        end

        def _default_fabric_path
          "fab"
        end

        def _default_python_path
          "/usr/bin/python"
        end

        def validate(env, errors)
          errors.add("fabfile does not exist.") if not File.exist?(fabfile_path)

          which_fabric_path = `which #{fabric_path}`
          errors.add("fabric command does not exist.") if not $?.success?

          fabfile_package = fabfile_path.gsub(".py", "").gsub("/", ".")
          output = `#{python_path} -c "exec 'import #{fabfile_package}'" &> /dev/null`
          errors.add("#{fabfile_package} could not import.") if not $?.success?

          for task in tasks
             package_path = "#{fabfile_package}.#{task}".gsub(".__init__", "")
             packages = package_path.split(".")
             output = `#{python_path} -c "exec 'from #{packages[0..-2].join('.')} import #{packages[-1]}'" &> /dev/null`
             errors.add("#{task} task does not exist.") if not $?.success?
           end
        end

        def fabfile_path
          @fabfile_path || _default_fabfile_path
        end

        def fabric_path
          @fabric_path || _default_fabric_path
        end

        def python_path
          @python_path || _default_python_path
        end

        def tasks
          @tasks ||= []
        end

        # Adds a recipe to the run list
        def add_task(name)
          tasks << name
        end
      end

      def self.config_class
        Config
      end

      def provision!
        ssh_info = env[:vm].ssh.info
        user = ssh_info[:username]
        host = ssh_info[:host]
        port = ssh_info[:port]
        private_key = ssh_info[:private_key_path]
        system "#{config.fabric_path} -i #{private_key} --config=#{config.fabfile_path} --user=#{user} --hosts=#{host} --port=#{port} #{config.tasks.join(' ')}"
      end
    end
  end
end

Got any usage examples?