Use Ruby's resolver by default and allow replace to be disabled

lib/vagrant.rb

@@ -254,6 +254,12 @@ if I18n.config.respond_to?(:enforce_available_locales=)
   I18n.config.enforce_available_locales = true
 end
 
+if Vagrant.enable_resolv_replace
+  global_logger.info("resolv replacement has been enabled!")
+else
+  global_logger.warn("resolv replacement has not been enabled!")
+end
+
 # Setup the plugin manager and load any defined plugins
 require_relative "vagrant/plugin/manager"
 plugins = Vagrant::Plugin::Manager.instance.installed_plugins

lib/vagrant/shared_helpers.rb

@@ -129,4 +129,20 @@ module Vagrant
       true
     end
   end
+
+  # Use Ruby Resolv in place of libc
+  #
+  # @return [boolean] enabled or not
+  def self.enable_resolv_replace
+    if !ENV["VAGRANT_DISABLE_RESOLV_REPLACE"]
+      begin
+        require "resolv-replace"
+        true
+      rescue
+        false
+      end
+    else
+      false
+    end
+  end
 end

website/source/docs/other/environmental-variables.html.md

@@ -218,3 +218,9 @@ If set, this will disable the ability to create symlinks with all virtualbox
 shared folders. Defaults to true if the option is not set. This can be overriden
 on a per-folder basis within your Vagrantfile config by settings the
 `SharedFoldersEnableSymlinksCreate` option to true.
+
+## `VAGRANT_DISABLE_RESOLV_REPLACE`
+
+Vagrant will automatically load `resolv-replace` to use Ruby's Resolv library
+in place of the libc resolver. This behavior can be disabled by setting this
+environment variable.