Make sure the machine is accessible when checking for the dhcp ip

lib/vagrant-lxc/container.rb

@@ -121,6 +121,14 @@ module Vagrant
           if ip.empty?
             raise LXC::Errors::ExecuteError, 'Unable to identify container ip'
           end
+
+          # Sometimes lxc reports the container as running before DNS is returning
+          # the right IP, so have to try a couple of times sometimes.
+          # Tks to https://github.com/neerolyte/vagueant/blob/master/bin/vagueant#L318-L330
+          r = raw "ping -c 1 #{ip} > /dev/null 2>&1"
+          if r.exit_code != 0
+            raise LXC::Errors::ExecuteError, 'Unable to reach container'
+          end
         end
         ip
       end

spec/support/unit_example_group.rb

@@ -5,6 +5,9 @@ module UnitExampleGroup
       Object.any_instance.stub(:system) { |*args, &block|
         UnitExampleGroup.prevent_system_calls(*args, &block)
       }
+      Object.any_instance.stub(:`) { |*args, &block|
+        UnitExampleGroup.prevent_system_calls(*args, &block)
+      }
       require 'vagrant/util/subprocess'
       Vagrant::Util::Subprocess.stub(:execute) { |*args, &block|
         UnitExampleGroup.prevent_system_calls(*args, &block)