This is a site specific script I use to bootstrap VMware templates using Chef, the knife-vsphere gem, and rbvmomi gem. It needs lots of work to make it less site specific, but shows how knife-vsphere and rbvmomi can be used to do some cool stuff.

bootstrap_vm_from_template.rb

#!/usr/bin/env ruby

# PREREQ:  YOU MUST HAVE A TEMPLATE ALREADY BUILT.  IF USING UBUNTU,
# MAKE SURE THE LAST STEP BEFORE YOU CREATE THE TEMPLATE IS THIS OR THE NETWORKING STEPS WON'T WORK.
# http://chris.dziemborowicz.com/blog/2010/07/25/fix-missing-eth0-when-cloning-ubuntu-vmware-virtual-machines/

require 'rubygems'
require 'awesome_print'
require 'net/ping'
require 'rbvmomi'
require 'trollop'
include Net

Ping::TCP.service_check = true


opts = Trollop::options do
  opt :ccpu, "Number of CPUs", :default => 1
  opt :cram, "Amount or RAM (in GB)", :default => 1
  opt :cspec, "Customization Spec", :type => :string
  opt :cvlan, "VLAN Name", :type => :string
  opt :dest_folder, "Destination Folder", :type => :string
  opt :name, "VM name", :type => :string, :required => true
  opt :pool, "Resource or Cluster Location", :type => :string
  opt :template, "Template Name", :type => :string
  opt :template_folder, "Template Folder", :type => :string
end

if opts[:dest_folder] == nil
  folder_list = `knife vsphere vm list -r --only-folders`.split("\n")
  folder_list.map! {|f| f.split(": ")[1]}
  folder_list.delete_if {|e| e == nil }
  folder_list.each_with_index {|e,i| puts "(#{i+1}) #{e}"}
  puts "Select Destination Folder for VM:"
  selection = gets.chomp.to_i
  if selection > folder_list.length || selection < 1
    puts "Invalid Input"
    exit
  end
  opts[:dest_folder] = folder_list.at(selection-1)
end

if opts[:cspec_list] == nil
  cspec_list = `knife vsphere customization list`.split("\n")
  cspec_list.map! {|f| f.split(": ")[1]}
  cspec_list.delete_if {|e| e == nil }
  cspec_list.each_with_index {|e,i| puts "(#{i+1}) #{e}"}
  puts "Select Customization Spec for VM:"
  selection = gets.chomp.to_i
  if selection > cspec_list.length || selection < 1
    puts "Invalid Input"
    exit
  end
  opts[:cspec] = cspec_list.at(selection-1)
end

if opts[:template_folder] == nil
  folder_list = `knife vsphere vm list -r --only-folders`.split("\n")
  folder_list.map! {|f| f.split(": ")[1]}
  folder_list.each_with_index {|e,i| puts "(#{i+1}) #{e}"}
  puts "Select Folder Location of Template:"
  selection = gets.chomp.to_i
  if selection > folder_list.length || selection < 1
    puts "Invalid Input"
    exit
  end
  opts[:template_folder] = folder_list.at(selection-1)
end

if opts[:template] == nil
  template_list = `knife vsphere template list -f #{opts[:template_folder]}`.split("\n")
  template_list.map! {|f| f.split(": ")[1]}
  template_list.delete_if {|e| e == nil }
  template_list.each_with_index {|e,i| puts "(#{i+1}) #{e}"}
  puts "Select Template for VM:"
  selection = gets.chomp.to_i
  if selection > template_list.length || selection < 1
    puts "Invalid Input"
    exit
  end
  opts[:template] = template_list.at(selection-1)
end

if opts[:cvlan] == nil
  cvlan_list = `knife vsphere vlan list`.split("\n")
  cvlan_list.map! {|f| f.split(": ")[1]}
  cvlan_list.delete_if {|e| e == nil }
  cvlan_list.each_with_index {|e,i| puts "(#{i+1}) #{e}"}
  puts "Select VLAN for VM:"
  selection = gets.chomp.to_i
  if selection > cvlan_list.length || selection < 1
    puts "Invalid Input"
    exit
  end
  opts[:cvlan] = cvlan_list.at(selection-1)
end

if opts[:pool] == nil
  pool_list = `knife vsphere pool list`.split("\n")
  pool_list.map! {|f| f.split(": ")[1]}
  pool_list.delete_if {|e| e == nil }
  pool_list.each_with_index {|e,i| puts "(#{i+1}) #{e}"}
  puts "Select Resource Pool or Cluster for VM:"
  selection = gets.chomp.to_i
  if selection > pool_list.length || selection < 1
    puts "Invalid Input"
    exit
  end
  opts[:pool] = pool_list.at(selection-1)
end
## YOU HAVE TO CUSTOMIZE THIS CASE BLOCK WITH YOUR OWN VMWARE NETWORKS
case opts[:cvlan]
when "Main-02-UNIX-pg"
  subnet = "10.50.2.0"
when "Main-08-ServerConsolidation-pg"
  subnet = "10.50.8.0"
else
  puts "No subnet defined for vlan #{opts[:cvlan]}.  Update script..."
  exit
end

puts "Cloning VM From Template with Knife (Chef)...this will take a few minutes..."
chef_vsphere_command = "knife vsphere vm clone #{opts[:name]} --dest-folder \"#{opts[:dest_folder]}\" -N #{opts[:name]} --cspec #{opts[:cspec]} --ccpu #{opts[:ccpu]} --cram #{opts[:cram]} --ctz \"America/Chicago\" --template #{opts[:template]} -f \"#{opts[:template_folder]}\" --cvlan #{opts[:cvlan]} --resource-pool \"#{opts[:pool]}\""
puts chef_vsphere_command
begin
  clone_vm = `#{chef_vsphere_command} 2>&1`
rescue Exception => e
  ap e
  puts "Clone Failed..."
  exit
end

if clone_vm.include?("no such") || clone_vm.include?("ERROR")
  puts "Clone Failed!! ===  #{clone_vm}"
  exit
end


puts "Resetting NIC (BUG: Is not connected after cloning)"


vim = RbVmomi::VIM.connect host: 'VCENTERSERVER', user: 'VCENTERUSER', password: 'VCENTERPASS', :insecure => true
dc = vim.serviceInstance.find_datacenter("DATACENTERNAME") or fail "datacenter not found"
vm = dc.find_vm("/#{opts[:dest_folder]}/#{opts[:name]}") or fail "VM not found"

dnic = vm.config.hardware.device.grep(RbVmomi::VIM::VirtualEthernetCard).find{|nic| nic.props}
port = dnic[:backing][:port]
dev_info = dnic[:deviceInfo]

if dnic[:connectable][:startConnected].eql?false
  spec = RbVmomi::VIM.VirtualMachineConfigSpec({
    :deviceChange => [{
      :operation => :remove,
      :device => dnic
    }]
  })
  puts "Removing NIC"
  vm.ReconfigVM_Task(:spec => spec).wait_for_completion
  puts "Adding NIC"
  spec = RbVmomi::VIM.VirtualMachineConfigSpec(
    :deviceChange => [{
      :operation => :add,
      :device => RbVmomi::VIM::VirtualVmxnet3(
        :key => 0,
        :deviceInfo => {
          :label => dev_info[:label],
          :summary => dev_info[:summary]
        },
        :backing => RbVmomi::VIM::VirtualEthernetCardDistributedVirtualPortBackingInfo(
          :port => port
        ),
        :addressType => 'generated'
      )
    }]
  )
  vm.ReconfigVM_Task(:spec => spec).wait_for_completion
end

puts "Creating DHCP Entry For New VM..."

mac_addr = vm.macs
if mac_addr.size > 1
  puts "Cannot process VMs with more than one NIC yet...exiting"
  exit
end
macaddress = mac_addr.values[0]
comment = "Created by Chef #{Date.today()}"
## THIS IS SITE SPECIFIC CODE TO MANAGE OUR DHCP.  YOU"LL HAVE TO CUSTOMIZE FOR YOUR OWN SITE.
#result = `ssh root@someserver ~/dhcp_maintenance/create_static_printer_or_host --add --showip --name #{opts[:name]} --macaddress #{macaddress} --subnet #{subnet} --ticket utech --uid utech --comment "#{comment}"`
#puts result

#if !result.include?("Entry added")
#  puts "Failed to add DHCP entry...exiting..."
#  exit
#end

ip_addr = result.split(": ")[1].chomp

puts "Starting VM #{opts[:name]}"
puts `knife vsphere vm state #{opts[:name]} -f "#{opts[:dest_folder]}" -s on`

puts "Waiting for SSH on #{ip_addr}..."


x = 0
alive = false
until x==25 || alive
  puts "."
  alive = Net::Ping::TCP.new(ip_addr, 22).ping?
  break if alive
  sleep 5
  x+=1
end

if !alive
  puts "VM is not running.  Cannot continue with Chef Bootstrap..."
  exit
end

## HAVE TO BOOTSTRAP IN TWO STEPS AT OUR SITE BECAUSE OF THE PROXY
puts "Bootstrapping Chef from Opscode"
`knife bootstrap #{ip_addr} -N #{opts[:name]} -x root -P PASS --bootstrap-proxy http://PROXYHOST:PORT -r 'role[base]'`
puts "Registering VM with Chef Server"
`knife bootstrap #{ip_addr} -N #{opts[:name]} -x root -P PASS -r 'role[base]'`