synced_folders/nfs: allow disabling export [GH-3636]

CHANGELOG.md

@@ -8,6 +8,8 @@ IMPROVEMENTS:
       RDP client. [GH-3686]
   - providers/docker: `build_args` config to specify extra args for
       `docker build`. [GH-3684]
+  - synced\_folders/nfs: Can tell Vagrant not to handle exporting
+      by setting `nfs_export: false` [GH-3636]
 
 BUG FIXES:
 

plugins/synced_folders/nfs/synced_folder.rb

@@ -60,6 +60,15 @@ module VagrantPlugins
         # and such on the folder itself.
         folders.each { |id, opts| prepare_folder(machine, opts) }
 
+        # Determine what folders we'll export
+        export_folders = folders.dup
+        export_folders.keys.each do |id|
+          opts = export_folders[id]
+          if opts.has_key?(:nfs_export) && !opts[:nfs_export]
+            export_folders.delete(id)
+          end
+        end
+
         # Export the folders. We do this with a class-wide lock because
         # NFS exporting often requires sudo privilege and we don't want
         # overlapping input requests. [GH-2680]
@@ -68,7 +77,8 @@ module VagrantPlugins
             machine.env.lock("nfs-export") do
               machine.ui.info I18n.t("vagrant.actions.vm.nfs.exporting")
               machine.env.host.capability(
-                :nfs_export, machine.ui, machine.id, machine_ip, folders)
+                :nfs_export,
+                machine.ui, machine.id, machine_ip, export_folders)
             end
           rescue Vagrant::Errors::EnvironmentLockedError
             sleep 1

website/docs/source/v2/synced-folders/nfs.html.md

@@ -55,6 +55,9 @@ unique to NFS. These are listed below. These options can be specified in
 the final part of the `config.vm.synced_folder` definition, along with the
 `type` option.
 
+* `nfs_export` (boolean) - If this is false, then Vagrant won't modify
+  your `/etc/exports` automatically and assumes you've done so already.
+
 * `nfs_udp` (boolean) - Whether or not to use UDP as the transport. UDP
   is faster but has some limitations (see the NFS documentation for more
   details). This defaults to true.