vagrant-lxc-ng/lib/vagrant-lxc/action/fetch_ip_with_lxc_attach.rb

module Vagrant
  module LXC
    module Action
      class FetchIpWithLxcAttach
        # Include this so we can use `Subprocess` more easily.
        include Vagrant::Util::Retryable

        def initialize(app, env)
          @app    = app
          @logger = Log4r::Logger.new("vagrant::lxc::action::fetch_ip_with_lxc_attach")
        end

        def call(env)
          env[:machine_ip] ||= assigned_ip(env)
        rescue LXC::Errors::NamespacesNotSupported
          @logger.info 'The `lxc-attach` command available does not support the --namespaces parameter, falling back to dnsmasq leases to fetch container ip'
        ensure
          @app.call(env)
        end

        def assigned_ip(env)
          driver = env[:machine].provider.driver
          ip = ''
          retryable(:on => LXC::Errors::ExecuteError, :tries => 10, :sleep => 3) do
            unless ip = get_container_ip_from_ip_addr(driver)
              # retry
              raise LXC::Errors::ExecuteError, :command => "lxc-attach"
            end
          end
          ip
        end

        # From: https://github.com/lxc/lxc/blob/staging/src/python-lxc/lxc/__init__.py#L371-L385
        def get_container_ip_from_ip_addr(driver)
          output = driver.attach '/sbin/ip', '-4', 'addr', 'show', 'scope', 'global', 'eth0', namespaces: ['network', 'mount']
          if output =~ /^\s+inet ([0-9.]+)\/[0-9]+\s+/
            return $1.to_s
          end
        end
      end
    end
  end
end