First stab at handling a custom lxc-dhcp IP

Will help on #23

lib/vagrant-lxc/config.rb

@@ -6,8 +6,15 @@ module Vagrant
       # @return [Array]
       attr_reader :start_opts
 
+      # The ip set for the built in LXC dhcp server (defaults to configured ip
+      # at /etc/default/lxc or 10.0.3.1)
+      #
+      # @return [String]
+      attr_accessor :lxc_dhcp_ip
+
       def initialize
-        @start_opts = []
+        @start_opts  = []
+        @lxc_dhcp_ip = '10.0.3.1'
       end
     end
   end

lib/vagrant-lxc/container.rb

@@ -115,7 +115,7 @@ module Vagrant
         end
       end
 
-      def dhcp_ip
+      def dhcp_ip(server_ip)
         ip = ''
         # Right after creation lxc reports the container as running
         # before DNS is returning the right IP, so have to wait for a while
@@ -123,7 +123,7 @@ module Vagrant
           # By default LXC supplies a dns server on 10.0.3.1 so we request the IP
           # of our target from there.
           # Tks to: https://github.com/neerolyte/vagueant/blob/master/bin/vagueant#L340
-          r = (raw 'dig', @name, '@10.0.3.1', '+short')
+          r = (raw 'dig', @name, "@#{server_ip}", '+short')
 
           # If the command was a failure then raise an exception that is nicely
           # handled by Vagrant.
@@ -131,7 +131,7 @@ module Vagrant
             if @interrupted
               @logger.info("Exit code != 0, but interrupted. Ignoring.")
             else
-              raise LXC::Errors::ExecuteError, :command => command.inspect
+              raise LXC::Errors::ExecuteError, :command => ['dig', @name, "@#{server_ip}", '+short'].inspect
             end
           end
 

lib/vagrant-lxc/provider.rb

@@ -52,7 +52,7 @@ module Vagrant
         return nil if state == :not_created
 
         {
-          :host => @container.dhcp_ip,
+          :host => @container.dhcp_ip(@machine.provider_config.lxc_dhcp_ip),
           :port => 22 # @driver.ssh_port(@machine.config.ssh.guest_port)
         }
       end

spec/unit/container_spec.rb

@@ -181,8 +181,9 @@ describe Vagrant::LXC::Container do
   end
 
   describe 'dhcp ip' do
-    let(:name) { 'random-container-name' }
-    let(:ip)   { "10.0.3.123" }
+    let(:name)      { 'random-container-name' }
+    let(:ip)        { "10.0.4.123" }
+    let(:server_ip) { "10.0.4.1" }
 
     before do
       subject.stub(:raw) {
@@ -191,8 +192,8 @@ describe Vagrant::LXC::Container do
     end
 
     it 'digs the container ip from lxc dns server' do
-      subject.dhcp_ip.should == ip
-      subject.should have_received(:raw).with('dig', name, '@10.0.3.1', '+short')
+      subject.dhcp_ip(server_ip).should == ip
+      subject.should have_received(:raw).with('dig', name, "@#{server_ip}", '+short')
     end
   end
 end