Automatically mount virtual box shared folder when machine reboots

This is done by adding the mount to fstab
ref: https://askubuntu.com/questions/252853/how-to-mount-a-virtualbox-shared-folder-at-startup

Note, add `nofail` to mount options so as to not stop machine from booting if device disappears

plugins/guests/linux/cap/mount_virtualbox_shared_folder.rb

@@ -11,8 +11,9 @@ module VagrantPlugins
 
           @@logger.debug("Mounting #{name} (#{options[:hostpath]} to #{guestpath})")
 
-          builtin_mount_type = "-cit vboxsf"
-          addon_mount_type = "-t vboxsf"
+          mount_type = "vboxsf"
+          builtin_mount_type = "-cit #{mount_type}"
+          addon_mount_type = "-t #{mount_type}"
 
           mount_options = options.fetch(:mount_options, [])
           detected_ids = detect_owner_group_ids(machine, guest_path, mount_options, options)
@@ -27,6 +28,10 @@ module VagrantPlugins
           # Create the guest path if it doesn't exist
           machine.communicate.sudo("mkdir -p #{guest_path}")
 
+          # Add mount to fstab so that if the machine reboots, will remount
+          fstab_entry = "#{name}  #{guest_path}  #{mount_type}  #{mount_options},nofail  0  0"
+          machine.communicate.sudo("grep -x '#{fstab_entry}' /etc/fstab || echo '#{fstab_entry}' >> /etc/fstab")
+
           stderr = ""
           result = machine.communicate.sudo(mount_command, error_check: false) do |type, data|
             stderr << data if type == :stderr

test/unit/plugins/guests/linux/cap/mount_virtual_box_shared_folder_test.rb

@@ -43,6 +43,7 @@ describe "VagrantPlugins::GuestLinux::Cap::MountVirtualBoxSharedFolder" do
       expect(comm).to receive(:execute).with("id -u #{mount_owner}", anything).and_yield(:stdout, mount_uid)
       expect(comm).to receive(:execute).with("getent group #{mount_group}", anything).and_yield(:stdout, "vagrant:x:#{mount_gid}:")
       expect(comm).to receive(:sudo).with("mount -t vboxsf -o uid=#{mount_uid},gid=#{mount_gid} #{mount_name} #{mount_guest_path}", anything)
+      expect(comm).to receive(:sudo).with(/\/etc\/fstab/)
       cap.mount_virtualbox_shared_folder(machine, mount_name, mount_guest_path, folder_options)
     end
 
@@ -50,6 +51,7 @@ describe "VagrantPlugins::GuestLinux::Cap::MountVirtualBoxSharedFolder" do
       expect(comm).to receive(:execute).with("id -u #{mount_owner}", anything).and_yield(:stdout, mount_uid)
       expect(comm).to receive(:execute).with("getent group #{mount_group}", anything).and_yield(:stdout, "vagrant:x:#{mount_gid}:")
       expect(comm).to receive(:sudo).with("mount -t vboxsf -o uid=#{mount_uid},gid=#{mount_gid} #{mount_name} #{mount_guest_path}", anything)
+      expect(comm).to receive(:sudo).with(/\/etc\/fstab/)
       expect(comm).to receive(:sudo).with("chown #{mount_uid}:#{mount_gid} #{mount_guest_path}")
       cap.mount_virtualbox_shared_folder(machine, mount_name, mount_guest_path, folder_options)
     end