Add support for specifying the default NIC type used for guest adapters

Provides support for defining the NIC type used for any guest adapter
which does not define an adapter type. This is defaulted to "virtio".

plugins/providers/virtualbox/action/network.rb

@@ -37,6 +37,8 @@ module VagrantPlugins
             available_slots.delete(slot)
           end
 
+          default_nic_type = env[:machine].provider_config.default_nic_type
+
           @logger.debug("Available slots for high-level adapters: #{available_slots.inspect}")
           @logger.info("Determining network adapters required for high-level configuration...")
           available_slots = available_slots.to_a.sort
@@ -44,6 +46,11 @@ module VagrantPlugins
             # We only handle private and public networks
             next if type != :private_network && type != :public_network
 
+            if default_nic_type && !options.key?(:nic_type) && !options.key?(:virtualbox__nic_type)
+              @logger.info("Setting default nic type (`#{default_nic_type}`) for `#{type}` - `#{options}`")
+              options[:virtualbox__nic_type] = default_nic_type
+            end
+
             options = scoped_hash_override(options, :virtualbox)
 
             # Figure out the slot that this adapter will go into
@@ -403,15 +410,16 @@ module VagrantPlugins
         end
 
         def nat_config(options)
-          return {
+          return options.merge(
             auto_config: false
-          }
+          )
         end
 
         def nat_adapter(config)
           return {
             adapter: config[:adapter],
             type:    :nat,
+            nic_type: config[:nic_type],
           }
         end
 

plugins/providers/virtualbox/config.rb

@@ -19,6 +19,13 @@ module VagrantPlugins
       # @return [Array]
       attr_reader :customizations
 
+      # Set the default type of NIC hardware to be used for network
+      # devices. By default this is "virtio". If it is set to `nil`
+      # no type will be set and VirtualBox's default will be used.
+      #
+      # @return [String]
+      attr_accessor :default_nic_type
+
       # 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
@@ -68,6 +75,7 @@ module VagrantPlugins
         @auto_nat_dns_proxy = UNSET_VALUE
         @check_guest_additions = UNSET_VALUE
         @customizations   = []
+        @default_nic_type = UNSET_VALUE
         @destroy_unused_network_interfaces = UNSET_VALUE
         @functional_vboxsf = UNSET_VALUE
         @name             = UNSET_VALUE
@@ -158,6 +166,9 @@ module VagrantPlugins
 
         # The default name is just nothing, and we default it
         @name = nil if @name == UNSET_VALUE
+
+        @default_nic_type = "virtio" if @default_nic_type == UNSET_VALUE
+        set_default_nic_type! if @default_nic_type
       end
 
       def validate(machine)
@@ -190,6 +201,15 @@ module VagrantPlugins
         { "VirtualBox Provider" => errors }
       end
 
+      def set_default_nic_type!
+        network_adapters.each do |_, args|
+          _, opts = args
+          if opts && !opts.key?(:nic_type)
+            opts[:nic_type] = @default_nic_type
+          end
+        end
+      end
+
       def to_s
         "VirtualBox"
       end

test/unit/plugins/providers/virtualbox/action/network_test.rb

@@ -84,6 +84,42 @@ describe VagrantPlugins::ProviderVirtualBox::Action::Network do
     expect{ subject.call(env) }.not_to raise_error(Vagrant::Errors::NetworkAddressInvalid)
   end
 
+  describe "setting nic type" do
+    before do
+      guest = double("guest")
+      allow(driver).to receive(:read_bridged_interfaces) { [] }
+      allow(driver).to receive(:read_host_only_interfaces) { [] }
+      allow(driver).to receive(:create_host_only_network) { {} }
+      allow(driver).to receive(:read_dhcp_servers) { [] }
+      allow(driver).to receive(:create_dhcp_server)
+      allow(machine).to receive(:guest) { guest }
+      allow(guest).to receive(:capability)
+    end
+
+    it "sets default nic type when unset" do
+      machine.config.vm.network 'private_network', { type: 'dhcp' }
+      subject.call(env)
+      _, net_config = machine.config.vm.networks.detect { |type, _| type == :private_network }
+      expect(net_config[:virtualbox__nic_type]).to eq("virtio")
+    end
+
+    it "does not set nic type when already set" do
+      machine.config.vm.network 'private_network', { type: 'dhcp', nic_type: "custom" }
+      subject.call(env)
+      _, net_config = machine.config.vm.networks.detect { |type, _| type == :private_network }
+      expect(net_config[:nic_type]).to eq("custom")
+      expect(net_config[:virtualbox__nic_type]).to be_nil
+    end
+
+    it "does not set nic type when namespaced option is set" do
+      machine.config.vm.network 'private_network', { type: 'dhcp', virtualbox__nic_type: "custom" }
+      subject.call(env)
+      _, net_config = machine.config.vm.networks.detect { |type, _| type == :private_network }
+      expect(net_config[:nic_type]).to be_nil
+      expect(net_config[:virtualbox__nic_type]).to eq("custom")
+    end
+  end
+
   context "with a dhcp private network" do
     let(:bridgedifs)  { [] }
     let(:hostonlyifs) { [] }
@@ -118,7 +154,7 @@ describe VagrantPlugins::ProviderVirtualBox::Action::Network do
         mac: nil,
         name: nil,
         netmask: "255.255.255.0",
-        nic_type: nil,
+        nic_type: "virtio",
         type: :dhcp,
         dhcp_ip: "172.28.128.2",
         dhcp_lower: "172.28.128.3",

test/unit/plugins/providers/virtualbox/config_test.rb

@@ -43,14 +43,42 @@ describe VagrantPlugins::ProviderVirtualBox::Config do
     it { expect(subject.gui).to be(false) }
     it { expect(subject.name).to be_nil }
     it { expect(subject.functional_vboxsf).to be(true) }
+    it { expect(subject.default_nic_type).to eq("virtio") }
 
     it "should have one NAT adapter" do
       expect(subject.network_adapters).to eql({
-        1 => [:nat, {}],
+        1 => [:nat, {nic_type: "virtio"}],
       })
     end
   end
 
+  describe "#default_nic_type" do
+    let(:nic_type) { "custom" }
+
+    before do
+      subject.default_nic_type = nic_type
+      subject.finalize!
+    end
+
+    it { expect(subject.default_nic_type).to eq(nic_type) }
+
+    it "should set NAT adapter nic type" do
+      expect(subject.network_adapters.values.first.last[:nic_type]).
+        to eq(nic_type)
+    end
+
+    context "when set to nil" do
+      let(:nic_type) { nil }
+
+      it { expect(subject.default_nic_type).to be_nil }
+
+      it "should not set NAT adapter nic type" do
+        expect(subject.network_adapters.values.first.last[:nic_type]).
+          to be_nil
+      end
+    end
+  end
+
   describe "#merge" do
     let(:one) { described_class.new }
     let(:two) { described_class.new }

website/source/docs/virtualbox/configuration.html.md

@@ -41,6 +41,27 @@ config.vm.provider "virtualbox" do |v|
 end
 ```
 
+## Default NIC Type
+
+By default Vagrant will set the NIC type for all network interfaces to
+`"virtio"`. If you would rather a different NIC type be used as the
+default for guests:
+
+```ruby
+config.vm.provider "virtualbox" do |v|
+  v.default_nic_type = "82543GC"
+end
+```
+
+or if you would like to disable the default type so VirtualBox's default
+is applied you can set the value to `nil`:
+
+```ruby
+config.vm.provider "virtualbox" do |v|
+  v.default_nic_type = nil
+end
+```
+
 ## Linked Clones
 
 By default new machines are created by importing the base box. For large