Use lxc-info instead of lxc-attach to retrieve container IP

`lxc-info -iH` to retrieve IP address was not available in early LXC
development but was there at LXC 1.0. Because we've bumped our minimum
LXC requirement to v1.0 recently, we can simplify the IP retrieval
process and also get rid of the `dnsmasq` fallback.

lib/vagrant-lxc/action.rb

@@ -4,8 +4,7 @@ require 'vagrant-lxc/action/create'
 require 'vagrant-lxc/action/destroy'
 require 'vagrant-lxc/action/destroy_confirm'
 require 'vagrant-lxc/action/compress_rootfs'
-require 'vagrant-lxc/action/fetch_ip_with_lxc_attach'
+require 'vagrant-lxc/action/fetch_ip_with_lxc_info'
-require 'vagrant-lxc/action/fetch_ip_from_dnsmasq_leases'
 require 'vagrant-lxc/action/forced_halt'
 require 'vagrant-lxc/action/forward_ports'
 require 'vagrant-lxc/action/gc_private_network_bridges'
@@ -182,8 +181,7 @@ module Vagrant
       def self.action_ssh_ip
         Builder.new.tap do |b|
           b.use Builtin::Call, Builtin::ConfigValidate do |env, b2|
-            b2.use FetchIpWithLxcAttach if env[:machine].provider.driver.supports_attach?
+            b2.use FetchIpWithLxcInfo
-            b2.use FetchIpFromDnsmasqLeases
           end
         end
       end

lib/vagrant-lxc/action/fetch_ip_from_dnsmasq_leases.rb

@@ -1,49 +0,0 @@
-module Vagrant
-  module LXC
-    module Action
-      class FetchIpFromDnsmasqLeases
-        def initialize(app, env)
-          @app    = app
-          @logger = Log4r::Logger.new("vagrant::lxc::action::fetch_ip_from_dnsmasq_leases")
-        end
-
-        def call(env)
-          env[:machine_ip] ||= assigned_ip(env)
-          @app.call(env)
-        end
-
-        def assigned_ip(env)
-          mac_address = env[:machine].provider.driver.mac_address
-          ip = nil
-          10.times do
-            dnsmasq_leases = read_dnsmasq_leases
-            @logger.debug "Attempting to load ip from dnsmasq leases (mac: #{mac_address})"
-            @logger.debug dnsmasq_leases
-            if dnsmasq_leases =~ /#{Regexp.escape mac_address.to_s}\s+([0-9.]+)\s+/i
-              ip = $1.to_s
-              break
-            else
-              @logger.debug 'Ip could not be parsed from dnsmasq leases file'
-              sleep 2
-            end
-          end
-          ip
-        end
-
-        LEASES_PATHS = %w(
-          /var/lib/misc/dnsmasq.*.leases
-          /var/lib/misc/dnsmasq.leases
-          /var/lib/dnsmasq/dnsmasq.leases
-          /var/db/dnsmasq.leases
-          /var/lib/libvirt/dnsmasq/*.leases
-        )
-
-        def read_dnsmasq_leases
-          Dir["{#{LEASES_PATHS.join(',')}}"].map do |file|
-            File.read(file)
-          end.join("\n")
-        end
-      end
-    end
-  end
-end

lib/vagrant-lxc/action/fetch_ip_with_lxc_info.rb

@@ -1,19 +1,17 @@
 module Vagrant
   module LXC
     module Action
-      class FetchIpWithLxcAttach
+      class FetchIpWithLxcInfo
         # 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")
+          @logger = Log4r::Logger.new("vagrant::lxc::action::fetch_ip_with_lxc_info")
         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
@@ -26,7 +24,7 @@ module Vagrant
           retryable(:on => LXC::Errors::ExecuteError, :tries => fetch_ip_tries, :sleep => 3) do
             unless ip = get_container_ip_from_ip_addr(driver)
               # retry
-              raise LXC::Errors::ExecuteError, :command => "lxc-attach"
+              raise LXC::Errors::ExecuteError, :command => "lxc-info"
             end
           end
           ip
@@ -34,8 +32,8 @@ module Vagrant
 
         # 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']
+          output = driver.info '-iH'
-          if output =~ /^\s+inet ([0-9.]+)\/[0-9]+\s+/
+          if output =~ /^([0-9.]+)/
             return $1.to_s
           end
         end

lib/vagrant-lxc/driver.rb

@@ -127,6 +127,10 @@ module Vagrant
         @cli.attach(*command)
       end
 
+      def info(*command)
+        @cli.info(*command)
+      end
+
       def configure_private_network(bridge_name, bridge_ip, container_name, address_type, ip)
         @logger.info "Configuring network interface for #{container_name} using #{ip} and bridge #{bridge_name}"
         if ip

lib/vagrant-lxc/driver/cli.rb

@@ -114,17 +114,17 @@ module Vagrant
             end
 
             if namespaces
-              if supports_attach_with_namespaces?
+              extra = ['--namespaces', namespaces]
-                extra = ['--namespaces', namespaces]
-              else
-                raise LXC::Errors::NamespacesNotSupported
-              end
             end
           end
 
           run :attach, '--name', @name, *((extra || []) + cmd)
         end
 
+        def info(*cmd)
+          run(:info, '--name', @name, *cmd)
+        end
+
         def transition_to(target_state, tries = 30, timeout = 1, &block)
           raise TransitionBlockNotProvided unless block_given?
 
@@ -170,14 +170,6 @@ module Vagrant
         def run(command, *args)
           @sudo_wrapper.run("lxc-#{command}", *args)
         end
-
-        def supports_attach_with_namespaces?
-          unless defined?(@supports_attach_with_namespaces)
-            @supports_attach_with_namespaces = run(:attach, '-h', :show_stderr => true).values.join.include?('--namespaces')
-          end
-
-          return @supports_attach_with_namespaces
-        end
       end
     end
   end

lib/vagrant-lxc/errors.rb

@@ -25,9 +25,6 @@ module Vagrant
       end
 
 
-      class NamespacesNotSupported < Vagrant::Errors::VagrantError
-      end
-
       class LxcLinuxRequired < Vagrant::Errors::VagrantError
         error_key(:lxc_linux_required)
       end

spec/unit/driver/cli_spec.rb

@@ -232,13 +232,6 @@ describe Vagrant::LXC::Driver::CLI do
       subject.attach *(command + [{namespaces: ['network', 'mount']}])
       expect(subject).to have_received(:run).with(:attach, '--name', name, '--namespaces', 'NETWORK|MOUNT', '--', *command)
     end
-
-    it 'raises a NamespacesNotSupported error if not supported' do
-      allow(subject).to receive(:run).with(:attach, '-h', :show_stderr => true).and_return({:stdout => '', :stderr => 'not supported'})
-      expect {
-        subject.attach *(command + [{namespaces: ['network', 'mount']}])
-      }.to raise_error(Vagrant::LXC::Errors::NamespacesNotSupported)
-    end
   end
 
   describe 'transition block' do

templates/sudoers.rb.erb

@@ -109,6 +109,7 @@ Whitelist.add_regex %r{<%= pipework_regex %>}, '**'
 Whitelist.add '<%= cmd_paths['lxc_bin'] %>/lxc-version'
 Whitelist.add '<%= cmd_paths['lxc_bin'] %>/lxc-ls'
 Whitelist.add '<%= cmd_paths['lxc_bin'] %>/lxc-info', '--name', /.*/
+Whitelist.add '<%= cmd_paths['lxc_bin'] %>/lxc-info', '--name', /.*/, '-iH'
 Whitelist.add '<%= cmd_paths['lxc_bin'] %>/lxc-create', '-B', /.*/, '--template', /.*/, '--name', /.*/, '**'
 Whitelist.add '<%= cmd_paths['lxc_bin'] %>/lxc-create', '--version'
 Whitelist.add '<%= cmd_paths['lxc_bin'] %>/lxc-destroy', '--name', /.*/