Add an extra_hosts option for additional entries such as VIP's.

This is necessary if you want to add a VIP to each host, or if you want
to define a host that isn't part of your vagrant infrastructure, but
which needs to be listed in your "DNS".

README.md

@@ -67,6 +67,13 @@ that all the added host entries have the:
 format. This is needed so that `hostname --fqdn` and `facter -p | grep fqdn`
 both work.
 
+If you set the `extra_hosts` configuration attribute, each hash in that list
+will be used to add additional elements to each /etc/hosts file. This is useful
+for defining a virtual IP, which doesn't correspond to a particular physical
+host, but which requires a DNS entry. Each element in the `extra_hosts` list
+should be a hash with three keys: `:ip`, `:host`, and `:aliases`. The first two
+should be strings, while the third should be a list of strings.
+
 Example configuration:
 
 ```ruby
@@ -77,6 +84,13 @@ Vagrant.configure("2") do |config|
  config.hostmanager.include_offline = true
  config.hostmanager.fqdn_friendly = true
  config.hostmanager.domain_name = 'example.com'
+ config.hostmanager.extra_hosts = [
+ {
+ :host => 'vip.example.com',
+ :ip => '192.168.42.253',
+ :aliases => ['vip'],
+ },
+ ]
  config.vm.define 'example-box' do |node|
  node.vm.hostname = 'example-box-hostname'
  node.vm.network :private_network, ip: '192.168.42.42'

lib/vagrant-hostmanager/config.rb

@@ -9,6 +9,7 @@ class Config < Vagrant.plugin('2', :config)
  attr_accessor :ip_resolver
  attr_accessor :fqdn_friendly
  attr_accessor :domain_name
+ attr_accessor :extra_hosts
 
  alias_method :enabled?, :enabled
  alias_method :include_offline?, :include_offline
@@ -23,6 +24,7 @@ def initialize
  @ip_resolver = UNSET_VALUE
  @fqdn_friendly = UNSET_VALUE
  @domain_name = UNSET_VALUE
+ @extra_hosts = UNSET_VALUE
  end
 
  def finalize!
@@ -34,6 +36,7 @@ def finalize!
  @ip_resolver = nil if @ip_resolver == UNSET_VALUE
  @fqdn_friendly = false if @fqdn_friendly == UNSET_VALUE
  @domain_name = '' if @domain_name == UNSET_VALUE
+ @extra_hosts = [] if @extra_hosts == UNSET_VALUE
 
  @aliases = [ @aliases ].flatten
  end

lib/vagrant-hostmanager/hosts_file/updater.rb

@@ -143,10 +143,16 @@ def get_machines
  end
 
  def get_new_content(header, footer, body, old_content)
+
+ extras = ''
+ @config.hostmanager.extra_hosts.each do |x|
+ extras+= ("#{x[:ip]}\t#{x[:host]}\t" + x[:aliases].join("\t") + "\n")
+ end
+
  if body.empty?
- block = "\n"
+ block = "\n" + extras
  else
- block = "\n\n" + header + body + footer + "\n"
+ block = "\n\n" + header + body + extras + footer + "\n"
  end
  # Pattern for finding existing block
  header_pattern = Regexp.quote(header)