kernel/v2: support merging properly

plugins/kernel_v2/config/vm.rb

@@ -65,7 +65,6 @@ module VagrantPlugins
           other_networks = other.instance_variable_get(:@__networks)
 
           result.instance_variable_set(:@__networks, @__networks.merge(other_networks))
-          result.instance_variable_set(:@provisioners, @provisioners + other.provisioners)
 
           # Merge defined VMs by first merging the defined VM keys,
           # preserving the order in which they were defined.
@@ -107,6 +106,27 @@ module VagrantPlugins
             new_overrides[key] += blocks
           end
 
+          # Merge provisioners. First we deal with overrides and making
+          # sure the ordering is good there. Then we merge them.
+          new_provs = []
+          @provisioners.each do |p|
+            if p.id
+              other_p = other.provisioners.find { |o| p.id == o.id }
+              if other_p
+                # There is an override. Take it.
+                other_p.config = p.config.merge(other_p.config)
+                next
+              end
+            end
+
+            # There is an override, merge it into the
+            new_provs << p.dup
+          end
+          other.provisioners.each do |p|
+            new_provs << p.dup
+          end
+          result.instance_variable_set(:@provisioners, new_provs)
+
           # Merge synced folders.
           other_folders = other.instance_variable_get(:@__synced_folders)
           new_folders = {}

plugins/kernel_v2/config/vm_provisioner.rb

@@ -18,7 +18,7 @@ module VagrantPlugins
       # The configuration associated with the provisioner, if there is any.
       #
       # @return [Object]
-      attr_reader :config
+      attr_accessor :config
 
       def initialize(id, name)
         @logger = Log4r::Logger.new("vagrant::config::vm::provisioner")
@@ -45,6 +45,11 @@ module VagrantPlugins
         end
       end
 
+      def initialize_copy(orig)
+        super
+        @config = @config.dup if @config
+      end
+
       def add_config(**options, &block)
         return if invalid?
 

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

@@ -36,5 +36,44 @@ describe VagrantPlugins::Kernel_V2::VMConfig do
       expect(r.length).to eql(1)
       expect(r[0]).to be_invalid
     end
+
+    describe "merging" do
+      it "copies the configs" do
+        subject.provision("shell", inline: "foo")
+        subject_provs = subject.provisioners
+
+        other = described_class.new
+        other.provision("shell", inline: "bar")
+
+        merged = subject.merge(other)
+        merged_provs = merged.provisioners
+
+        expect(merged_provs.length).to eql(2)
+        expect(merged_provs[0].config.inline).
+          to eq(subject_provs[0].config.inline)
+        expect(merged_provs[0].config.object_id).
+          to_not eq(subject_provs[0].config.object_id)
+      end
+
+      it "uses the proper order when merging overrides" do
+        subject.provision("shell", inline: "foo", id: "original")
+        subject.provision("shell", inline: "other", id: "other")
+
+        other = described_class.new
+        other.provision("shell", inline: "bar")
+        other.provision("shell", inline: "foo-overload", id: "original")
+
+        merged = subject.merge(other)
+        merged_provs = merged.provisioners
+
+        expect(merged_provs.length).to eql(3)
+        expect(merged_provs[0].config.inline).
+          to eq("other")
+        expect(merged_provs[1].config.inline).
+          to eq("bar")
+        expect(merged_provs[2].config.inline).
+          to eq("foo-overload")
+      end
+    end
   end
 end