VirtualBox no longer removes network interfaces [GH-1324]

CHANGELOG.md

@@ -8,6 +8,11 @@ FEATURES:
   - VirtualBox VBoxManage customizations can now be specified to run
     pre-boot (the default and existing functionality, pre-import,
     or post-boot. [GH-1247]
+  - VirtualBox no longer destroys unused network interfaces by default.
+    This didn't work across multi-user systems and required admin privileges
+    on Windows, so it has been disabled by default. It can be enabled using
+    the VirtualBox provider-specific `destroy_unused_network_interfaces`
+    configuration by setting it to true. [GH-1324]
 
 IMPROVEMENTS:
 

plugins/providers/virtualbox/action/destroy_unused_network_interfaces.rb

@@ -1,14 +1,20 @@
+require "log4r"
+
 module VagrantPlugins
   module ProviderVirtualBox
     module Action
       class DestroyUnusedNetworkInterfaces
         def initialize(app, env)
           @app = app
+          @logger = Log4r::Logger.new("vagrant::plugins::virtualbox::destroy_unused_netifs")
         end
 
         def call(env)
-          env[:machine].provider.driver.delete_unused_host_only_networks
-          @app.call(env)
+          if env[:machine].provider_config.destroy_unused_network_interfaces
+            @logger.info("Destroying unused network interfaces...")
+            env[:machine].provider.driver.delete_unused_host_only_networks
+            @app.call(env)
+          end
         end
       end
     end

plugins/providers/virtualbox/config.rb

@@ -13,6 +13,14 @@ module VagrantPlugins
       # @return [Array]
       attr_reader :customizations
 
+      # If true, unused network interfaces will automatically be deleted.
+      # This defaults to false because the detection does not work across
+      # multiple users, and because on Windows this operation requires
+      # administrative privileges.
+      #
+      # @return [Boolean]
+      attr_accessor :destroy_unused_network_interfaces
+
       # If set to `true`, then VirtualBox will be launched with a GUI.
       #
       # @return [Boolean]
@@ -32,6 +40,7 @@ module VagrantPlugins
       def initialize
         @auto_nat_dns_proxy = UNSET_VALUE
         @customizations   = []
+        @destroy_unused_network_interfaces = UNSET_VALUE
         @name             = UNSET_VALUE
         @network_adapters = {}
         @gui              = UNSET_VALUE
@@ -73,6 +82,10 @@ module VagrantPlugins
         # Default is to auto the DNS proxy
         @auto_nat_dns_proxy = true if @auto_nat_dns_proxy == UNSET_VALUE
 
+        if @destroy_unused_network_interfaces == UNSET_VALUE
+          @destroy_unused_network_interfaces = false
+        end
+
         # Default is to not show a GUI
         @gui = false if @gui == UNSET_VALUE