feat: notify diego of route updates (#4298)

* feat: notify diego of route updates

After updating a route via the new update route endpoint, it was only
stored in the database. Since routes can be changed without restarting
the application this commit adds logic to also push the update to diego.

Resolves: #4286
Co-Authored-By: Clemens Hoffmann <[email protected]>

* Verify call to notify_backend_of_route_update in route.update

* Address review comments

* Notify diego outside of transaction

---------

Co-authored-by: Clemens Hoffmann <[email protected]>

Author: maxmoehl

app/actions/route_update.rb

@@ -3,11 +3,15 @@ class RouteUpdate
     def update(route:, message:)
       Route.db.transaction do
         route.options = route.options.symbolize_keys.merge(message.options).compact if message.requested?(:options)
-
         route.save
         MetadataUpdate.update(route, message)
       end
 
+      if message.requested?(:options)
+        route.apps.each do |process|
+          ProcessRouteHandler.new(process).notify_backend_of_route_update
+        end
+      end
       route
     end
   end

spec/unit/actions/route_update_spec.rb

@@ -41,10 +41,16 @@ module VCAP::CloudController
     end
 
     let(:message) { RouteUpdateMessage.new(body) }
-    let(:route) { Route.make }
+    let(:process) { ProcessModel.make }
+    let(:route_mapping) { RouteMappingModel.make(app: process.app) }
+    let(:route) { route_mapping.route }
 
     subject { RouteUpdate.new }
     describe '#update metadata' do
+      before do
+        expect(ProcessRouteHandler).not_to receive(:new)
+      end
+
       context 'when the route has no existing metadata' do
         context 'when no metadata is specified' do
           let(:body) do
@@ -135,6 +141,13 @@ module VCAP::CloudController
     end
 
     describe '#update options' do
+      let(:fake_route_handler) { instance_double(ProcessRouteHandler) }
+
+      before do
+        allow(ProcessRouteHandler).to receive(:new).with(process).and_return(fake_route_handler)
+        allow(fake_route_handler).to receive(:notify_backend_of_route_update)
+      end
+
       context 'when the route has no existing options' do
         context 'when no options are specified' do
           let(:body) do
@@ -147,6 +160,11 @@ module VCAP::CloudController
             route.reload
             expect(route.options).to eq({})
           end
+
+          it 'does not notifies the backend' do
+            expect(fake_route_handler).not_to receive(:notify_backend_of_route_update)
+            subject.update(route:, message:)
+          end
         end
 
         context 'when an option is specified' do
@@ -161,10 +179,14 @@ module VCAP::CloudController
           it 'adds the route option' do
             expect(message).to be_valid
             subject.update(route:, message:)
-
             route.reload
             expect(route[:options]).to eq('{"loadbalancing":"round-robin"}')
           end
+
+          it 'notifies the backend' do
+            expect(fake_route_handler).to receive(:notify_backend_of_route_update)
+            subject.update(route:, message:)
+          end
         end
       end
 
@@ -184,6 +206,11 @@ module VCAP::CloudController
             route.reload
             expect(route.options).to include({ 'loadbalancing' => 'round-robin' })
           end
+
+          it 'does not notifies the backend' do
+            expect(fake_route_handler).not_to receive(:notify_backend_of_route_update)
+            subject.update(route:, message:)
+          end
         end
 
         context 'when an option is specified' do
@@ -199,9 +226,13 @@ module VCAP::CloudController
             expect(message).to be_valid
             subject.update(route:, message:)
             route.reload
-
             expect(route.options).to include({ 'loadbalancing' => 'least-connection' })
           end
+
+          it 'notifies the backend' do
+            expect(fake_route_handler).to receive(:notify_backend_of_route_update)
+            subject.update(route:, message:)
+          end
         end
 
         context 'when the option value is set to null' do
@@ -219,6 +250,11 @@ module VCAP::CloudController
             route.reload
             expect(route.options).to eq({})
           end
+
+          it 'notifies the backend' do
+            expect(fake_route_handler).to receive(:notify_backend_of_route_update)
+            subject.update(route:, message:)
+          end
         end
       end
     end