Class: BoxGrinder::LibvirtCapabilities

Inherits:
Object
  • Object
show all
Defined in:
lib/boxgrinder-build/plugins/delivery/libvirt/libvirt-capabilities.rb

Defined Under Namespace

Classes: Domain, Plugin

Constant Summary collapse

DEFAULT_DOMAIN_MAPPINGS =

Arrays are populated in order of precedence. Best first.

{
  :xen =>  { :bus => :xen, :virt_rank => [:xen, :linux, :hvm] },
  :kqemu => { :bus => :virtio, :virt_rank => [:hvm] },
  :kvm => { :bus => :virtio, :virt_rank => [:xen, :linux, :hvm] },
  :qemu => { :bus => :ide, :virt_rank => [:xen, :linux, :hvm] },
  :vbox => { :bus => :virtio, :virt_rank => [:hvm] },
  :vmware => { :bus => :ide, :virt_rank => [:hvm] }
}
PLUGIN_MAPPINGS = 
{
  :default => { :domain_rank => [:kvm, :xen, :kqemu, :qemu] },
  :virtualbox => { :domain_rank => [:vbox] },
  :xen => { :domain_rank => [:xen] },
  :citrix => { :domain_rank => [:xen] },
  :kvm => { :domain_rank => [:kvm] },
  :vmware => { :domain_rank => [:vmware] },
  :ec2 => { :domain_rank => [:xen, :qemu] }
}
DOMAINS = 
DEFAULT_DOMAIN_MAPPINGS.inject({}) do |accum, mapping|
  accum.merge(mapping.first => Domain.new(mapping.first, mapping.last[:bus], mapping.last[:virt_rank]))
end
PLUGINS = 
PLUGIN_MAPPINGS.inject({}) do |accum, mapping|
  d_refs = mapping.last[:domain_rank].collect{|d| DOMAINS[d]}
  accum.merge(mapping.first => Plugin.new(mapping.first, d_refs))
end

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ LibvirtCapabilities

Returns a new instance of LibvirtCapabilities.



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# File 'lib/boxgrinder-build/plugins/delivery/libvirt/libvirt-capabilities.rb', line 90

def initialize(opts={})
  @log = opts[:log] || LogHelper.new
end

Instance Method Details

#build_guest(xml) ⇒ Object 



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# File 'lib/boxgrinder-build/plugins/delivery/libvirt/libvirt-capabilities.rb', line 133

def build_guest(xml)
  dom = DOMAINS[xpath_first_intern(xml, ".//domain/@type")]
  bus = 'ide'
  bus = dom.bus if dom

  OpenStruct.new({
    :domain_type => xpath_first_intern(xml, ".//domain/@type"),
    :os_type => xpath_first_intern(xml, './/os_type'),
    :bus => bus
  })
end

#determine_capabilities(conn, previous_plugin_info) ⇒ Object

Connect to the remote machine and determine the best available settings



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# File 'lib/boxgrinder-build/plugins/delivery/libvirt/libvirt-capabilities.rb', line 95

def determine_capabilities(conn, previous_plugin_info)
  plugin = get_plugin(previous_plugin_info)
  root = Nokogiri::XML.parse(conn.capabilities)
  guests = root.xpath("//guest/arch[@name='x86_64']/..")

  guests = guests.sort do |a, b|
    dom_maps = [a,b].map { |x| plugin.domain_map[xpath_first_intern(x, './/domain/@type')] }

    # Handle unknown mappings
    next resolve_unknowns(dom_maps) if dom_maps.include?(nil)

    # Compare according to domain ranking
    dom_rank = dom_maps.map { |m| m[:rank]}.reduce(:<=>)

    # Compare according to virtualisation ranking
    virt_rank = [a,b].enum_for(:each_with_index).map do |x, i|
      dom_maps[i][:domain].virt_map[xpath_first_intern(x, './/os_type')]
    end

    # Handle unknown mappings
    next resolve_unknowns(virt_rank) if virt_rank.include?(nil)

    # Domain rank first
    next dom_rank unless dom_rank == 0

    # OS type rank second
    virt_rank.reduce(:<=>)
  end
  # Favourite!
  build_guest(guests.first)
end

#get_plugin(previous_plugin_info) ⇒ Object

At present we don't have enough meta-data to work with to easily generalise, so we have to assume defaults often. This is something to improve later.



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# File 'lib/boxgrinder-build/plugins/delivery/libvirt/libvirt-capabilities.rb', line 151

def get_plugin(previous_plugin_info)
  if previous_plugin_info[:type] == :platform
    if PLUGINS.has_key?(previous_plugin_info[:name])
      @log.debug("Using #{previous_plugin_info[:name]} mapping")
      return PLUGINS[previous_plugin_info[:name]]
    else
      @log.debug("This plugin does not know what mappings to choose, so will assume default values where user values are not provided.")
    end
  end
  @log.debug("Using default domain mappings.")
  PLUGINS[:default]
end

#resolve_unknowns(pair) ⇒ Object 



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# File 'lib/boxgrinder-build/plugins/delivery/libvirt/libvirt-capabilities.rb', line 127

def resolve_unknowns(pair)
  return 0 if pair.first.nil? and pair.last.nil?
  return 1 if pair.first.nil?
  -1 if pair.last.nil?
end

#xpath_first_intern(xml, path) ⇒ Object 



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# File 'lib/boxgrinder-build/plugins/delivery/libvirt/libvirt-capabilities.rb', line 145

def xpath_first_intern(xml, path)
  xml.xpath(path).first.text.intern
end