Add a :libvirt__always_destroy flag to network definitions (#1381)

This ensures that a network is always appended to the created_networks
file, to avoid the case where a domain that created the network gets
destroyed first during cleanup, therefore skipping the network destroy
because some other domain is still using it. Since the second domain did
not create the network, the existing behaviour is that it gets left
behind.

Seting :libvirt__always_destroy to true will ensure that the domain will
destroy the network even if it did not create it, if there are no other
users of the network remaining.

README.md

@@ -906,6 +906,9 @@ starts with `libvirt__` string. Here is a list of those options:
   If not specified the default is 'false'.
 * `:bus` - The bus of the PCI device. Both :bus and :slot have to be defined.
 * `:slot` - The slot of the PCI device. Both :bus and :slot have to be defined.
+* `:libvirt__always_destroy` - Allow domains that use but did not create a
+  network to destroy it when the domain is destroyed (default: `true`). Set to
+  `false` to only allow the domain that created the network to destroy it.
 
 When the option `:libvirt__dhcp_enabled` is to to 'false' it shouldn't matter
 whether the virtual network contains a DHCP server or not and vagrant-libvirt

lib/vagrant-libvirt/action/create_networks.rb

@@ -208,6 +208,9 @@ module VagrantPlugins
 
             # Create a private network.
             create_private_network(env)
+            write_created_network(env)
+          else
+            write_created_network(env) unless @options[:always_destroy] == false
           end
         end
 
@@ -247,6 +250,9 @@ module VagrantPlugins
 
             # Create a private network.
             create_private_network(env)
+            write_created_network(env)
+          else
+            write_created_network(env) unless @options[:always_destroy] == false
           end
         end
 
@@ -273,6 +279,9 @@ module VagrantPlugins
 
             # Create a private network.
             create_private_network(env)
+            write_created_network(env)
+          else
+            write_created_network(env) unless @options[:always_destroy] == false
           end
         end
 
@@ -347,7 +356,9 @@ module VagrantPlugins
           rescue => e
             raise Errors::CreateNetworkError, error_message: e.message
           end
+        end
 
+        def write_created_network(env)
           created_networks_file = env[:machine].data_dir + 'created_networks'
 
           message = 'Saving information about created network ' \

lib/vagrant-libvirt/util/network_util.rb

@@ -119,7 +119,8 @@ module VagrantPlugins
                             IPAddr.new(options[:network_address]).get_mask :
                             '255.255.255.0',
               dhcp_enabled: true,
-              forward_mode: 'nat'
+              forward_mode: 'nat',
+              always_destroy: true
             }.merge(options)
 
             if options[:type].to_s == 'dhcp' && options[:ip].nil?