Add check for /etc/fstab

plugins/guests/linux/cap/persist_mount_shared_folder.rb

@@ -8,6 +8,8 @@ module VagrantPlugins
       class PersistMountSharedFolder
         extend SyncedFolder::UnixMountHelpers
 
+        @@logger = Log4r::Logger.new("vagrant::guest::linux::persist_mount_shared_folders")
+
         # Inserts fstab entry for a set of synced folders. Will fully replace
         # the currently managed group of Vagrant managed entries. Note, passing
         # empty list of folders will just remove entries
@@ -15,7 +17,13 @@ module VagrantPlugins
         # @param [Machine] machine The machine to run the action on
         # @param [Map<String, Map>] A map of folders to add to fstab
         def self.persist_mount_shared_folder(machine, folders)
+          if !fstab_exists?(machine)
+            @@logger.info("no fstab file found, not modifying /etc/fstab")
+            return
+          end
+
           if folders.nil?
+            @@logger.info("clearing /etc/fstab")
             self.remove_vagrant_managed_fstab(machine)
             return
           end
@@ -53,6 +61,10 @@ module VagrantPlugins
 
         private
 
+        def self.fstab_exists?(machine)
+          machine.communicate.test("test -f /etc/fstab")
+        end
+
         def self.remove_vagrant_managed_fstab(machine)
           machine.communicate.sudo("sed -i '/\#VAGRANT-BEGIN/,/\#VAGRANT-END/d' /etc/fstab")
         end

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

@@ -37,6 +37,7 @@ describe "VagrantPlugins::GuestLinux::Cap::PersistMountSharedFolder" do
     allow(folder_plugin).to receive(:capability).with(:mount_options, any_args).
       and_return(["uid=#{options_uid},gid=#{options_gid}", options_uid, options_gid])
     allow(folder_plugin).to receive(:capability).with(:mount_type).and_return("vboxsf")
+    allow(cap).to receive(:fstab_exists?).and_return(true)
   end
 
   after do
@@ -78,5 +79,17 @@ describe "VagrantPlugins::GuestLinux::Cap::PersistMountSharedFolder" do
         cap.persist_mount_shared_folder(machine, folders)
       end
     end
+
+    context "fstab does not exist" do
+      before do
+        allow(cap).to receive(:fstab_exists?).and_return(false)
+      end
+
+      it "does not modify /etc/fstab" do
+        expect(cap).not_to receive(:remove_vagrant_managed_fstab)
+        expect(comm).not_to receive(:sudo).with(/echo '' >> \/etc\/fstab/)
+        cap.persist_mount_shared_folder(machine, folders)
+      end
+    end
   end
 end