_form.html.erb

<% form_for @hypervisor do |f| %>
  <%= base_errors_for @hypervisor %>
  <%= text_f f, :name %>
  <%= text_f f, :uri, :label => "URI", :class =>"xxlarge" %>
  <%= text_f f, :hyperuser, :label => "Username", :class => "xxlarge" %>
  <%= password_f f, :hyperpass, :label => "Password" %>>
  <%= selectable_f f, :kind, Hypervisor::KINDS %>
  <%= submit_or_cancel f %>
<% end %>


hypervisor.rb model

# only line that references hyperuser and hyperpass
def connect
    return true if Rails.env == "test"
    logger.debug "trying to contact Hypervisor #{name}"
    Timeout::timeout(10, StandardError) { @host = Virt.connect(uri, hyperuser, hyperpass).host }
  rescue => e
    logger.warn "Failed to connect to hypervisor #{name} - #{e}"
    @host = nil
    raise
  end


new migration

class AddHypervisorCredentials < ActiveRecord::Migration
  def self.up
        add_column :hypervisors, :hyperuser,  :string
        add_column :hypervisors, :hyperpass, :string

  end

  def self.down
        remove_column :hypervisors, :hyperuser
        remove_column :hypervisors, :hyperpass
  end
end


virt.rb

require 'virt/util'
require 'virt/connection'
require 'virt/host'
require 'virt/guest'
require 'virt/pool'
require 'virt/volume'
require 'virt/interface'
module Virt

  class << self

    def connect( uri, hyperuser, hyperpass)
      #hyperuser = "root"
      #uri = 'esx://192.168.1.19?no_verify=1'
      #hyperpass = "changeme"
      @connection = Virt::Connection.new(uri, hyperuser, hyperpass)
      puts @connection.version
    end

    def connection
      return @connection if @connection and !@connection.closed?
      raise "No Connection or connection has been closed"
    end

  end

end


### Connection.rb from virt lib ####
require 'libvirt'
module Virt
    class Connection
        attr_reader :connection

        def initialize(uri, hyperuser, hyperpass)
            raise("Must provide a guest to connect to") unless uri
            @connection = Libvirt::open_auth(uri,
                                             [Libvirt::CRED_AUTHNAME, Libvirt::CRED_PASSPHRASE],
                                             "my data") do |cred|

                if cred["type"] == Libvirt::CRED_AUTHNAME
                    res = hyperuser
                elsif cred["type"] == Libvirt::CRED_PASSPHRASE
                    res = hyperpass
                else
                    raise "Unsupported credential #{cred['type']}"
                end

            end
        puts @connection.version

            #  @connection = Libvirt::open uri
        end

        def closed?
            connection.closed?
        end

        def secure?
            connection.encrypted?
        end

        def version
            connection.libversion
        end

        def disconnect
            connection.close
        end

        def host
            Host.new
        end
    end
end