Add option to disable modification of /etc/hosts on guest

lib/vagrant/action/builtin/set_hostname.rb

@@ -10,15 +10,19 @@ module Vagrant
       class SetHostname
         def initialize(app, env)
           @app = app
+          @logger = Log4r::Logger.new("vagrant::action::builtin::set_hostname")
         end
 
         def call(env)
           @app.call(env)
 
           hostname = env[:machine].config.vm.hostname
-          if !hostname.nil?
+          disable_hosts_modification = env[:machine].config.vm.disable_hosts_modification
+          if !hostname.nil? && !disable_hosts_modification
             env[:ui].info I18n.t("vagrant.actions.vm.hostname.setting")
             env[:machine].guest.capability(:change_host_name, hostname)
+          else
+            @logger.info("`disable_hosts_modification` set to true. Hosts modification has been disabled, skiping changing hostname.")
           end
         end
       end

plugins/kernel_v2/config/vm.rb

@@ -42,6 +42,7 @@ module VagrantPlugins
       attr_accessor :box_download_location_trusted
       attr_accessor :box_download_options
       attr_accessor :communicator
+      attr_accessor :disable_hosts_modification
       attr_accessor :graceful_halt_timeout
       attr_accessor :guest
       attr_accessor :hostname
@@ -77,6 +78,7 @@ module VagrantPlugins
         @box_extra_download_options    = UNSET_VALUE
         @box_url                       = UNSET_VALUE
         @box_version                   = UNSET_VALUE
+        @disable_hosts_modification    = UNSET_VALUE
         @clone                         = UNSET_VALUE
         @communicator                  = UNSET_VALUE
         @graceful_halt_timeout         = UNSET_VALUE
@@ -527,6 +529,7 @@ module VagrantPlugins
         @box_version = nil if @box_version == UNSET_VALUE
         @box_download_options = {} if @box_download_options == UNSET_VALUE
         @box_extra_download_options = Vagrant::Util::MapCommandOptions.map_to_command_options(@box_download_options)
+        @disable_hosts_modification = false if @disable_hosts_modification == UNSET_VALUE
         @clone = nil if @clone == UNSET_VALUE
         @communicator = nil if @communicator == UNSET_VALUE
         @graceful_halt_timeout = 60 if @graceful_halt_timeout == UNSET_VALUE
@@ -994,6 +997,9 @@ module VagrantPlugins
         if ![TrueClass, FalseClass].include?(@allow_fstab_modification.class)
           errors["vm"] << I18n.t("vagrant.config.vm.config_type",
             option: "allow_fstab_modification", given: @allow_fstab_modification.class, required: "Boolean"
+        if ![TrueClass, FalseClass].include?(@disable_hosts_modification.class)
+          errors["vm"] << I18n.t("vagrant.config.vm.disable_host_modification_type",
+            given: @disable_hosts_modification.class
           )
         end
 

templates/locales/en.yml

@@ -1941,6 +1941,8 @@ en:
           Checksum type specified but "box_download_checksum" is blank
         box_download_checksum_notblank: |-
           Checksum specified but must also specify "box_download_checksum_type"
+        disable_host_modification_type: |-
+          Expected configuration `disable_hosts_modification` to be type Bool, got %{given}
         box_missing: "A box must be specified."
         box_download_options_type: |-
           Found "box_download_options" specified as type '%{type}', should be a Hash

test/unit/plugins/kernel_v2/config/vm_test.rb

@@ -49,6 +49,20 @@ describe VagrantPlugins::Kernel_V2::VMConfig do
     assert_valid
   end
 
+  it  "validates disables_host_modification option" do
+    subject.disable_hosts_modification = true
+    subject.finalize!
+    assert_valid
+
+    subject.disable_hosts_modification = false
+    subject.finalize!
+    assert_valid
+
+    subject.disable_hosts_modification = "truthy"
+    subject.finalize!
+    assert_invalid
+  end
+
   describe "#base_mac" do
     it "defaults properly" do
       subject.finalize!

test/unit/vagrant/action/builtin/set_hostname_test.rb

@@ -0,0 +1,28 @@
+require File.expand_path("../../../../base", __FILE__)
+
+describe Vagrant::Action::Builtin::SetHostname do
+  let(:env) { { machine: machine, ui: ui } }
+  let(:app) { lambda { |env| } }
+  let(:machine) { double("machine") }
+  let(:ui) { double("ui") }
+  
+  subject { described_class.new(app, env) }
+
+  before do 
+    allow(machine).to receive_message_chain(:config, :vm, :hostname).and_return("whatever")
+    allow(machine).to receive_message_chain(:guest, :capability)
+    allow(ui).to receive(:info)
+  end
+
+  it "should change hostname if hosts modification enabled" do
+    allow(machine).to receive_message_chain(:config, :vm, :disable_hosts_modification).and_return(false)
+    expect(machine).to receive(:guest)
+    subject.call(env)
+  end
+
+  it "should not change hostname if hosts modification disabled" do
+    allow(machine).to receive_message_chain(:config, :vm, :disable_hosts_modification).and_return(true)
+    expect(machine).not_to receive(:guest)
+    subject.call(env)
+  end
+end