v3: Return helpful errors when talking to Routing API

This commit introduces a generic `service_unavailable` error that
corresponds to a 503.

[#162395328]

Co-authored-by: Belinda Liu <bliu@pivotal.io>

Author: monamohebbi

app/controllers/v3/application_controller.rb

@@ -30,6 +30,10 @@ def bad_request!(message)
     raise CloudController::Errors::ApiError.new_from_details('BadRequest', message)
   end
 
+  def service_unavailable!(message)
+    raise CloudController::Errors::ApiError.new_from_details('ServiceUnavailable', message)
+  end
+
   def resource_not_found!(resource)
     raise CloudController::Errors::NotFound.new_from_details('ResourceNotFound', "#{resource.to_s.humanize} not found")
   end

app/controllers/v3/domains_controller.rb

@@ -42,7 +42,7 @@ def create
       unauthorized! unless permission_queryer.can_write_globally?
     end
 
-    if message.router_group_guid.present? && router_group_not_found?(message.router_group_guid)
+    if message.router_group_guid.present? && fetch_router_group(message.router_group_guid).nil?
       unprocessable!("Router group with guid '#{message.router_group_guid}' not found.")
     end
     domain = DomainCreate.new.create(message: message, shared_organizations: shared_org_objects)
@@ -211,7 +211,14 @@ def find_missing_guid(db_organizations, message_shared_org_guids)
     (message_shared_org_guids - db_organizations.map(&:guid)).first
   end
 
-  def router_group_not_found?(router_group_guid)
-    !CloudController::DependencyLocator.instance.routing_api_client.router_group(router_group_guid)
+  def fetch_router_group(router_group_guid)
+    routing_client = CloudController::DependencyLocator.instance.routing_api_client
+    service_unavailable!('The Routing API is disabled.') unless routing_client.enabled?
+
+    routing_client.router_group(router_group_guid)
+  rescue RoutingApi::RoutingApiUnavailable
+    service_unavailable!('The Routing API is currently unavailable. Please try again later.')
+  rescue RoutingApi::UaaUnavailable
+    service_unavailable!('Communicating with the Routing API failed because UAA is currently unavailable. Please try again later.')
   end
 end

spec/request/domains_spec.rb

@@ -15,6 +15,7 @@
     allow(VCAP::CloudController::RoutingApi::Client).to receive(:new).and_return(routing_api_client)
     allow(routing_api_client).to receive(:router_group).with('some-router-guid').and_return router_group
     allow(routing_api_client).to receive(:router_group).with('some-other-router-guid').and_return nil
+    allow(routing_api_client).to receive(:enabled?).and_return true
   end
 
   describe 'GET /v3/domains' do
@@ -788,6 +789,51 @@
       end
 
       it_behaves_like 'permissions for single object endpoint', ALL_PERMISSIONS
+
+      context 'when the Routing API is unavailable' do
+        let(:user_header) { admin_headers_for(user) }
+
+        before do
+          allow(routing_api_client).to receive(:router_group).and_raise VCAP::CloudController::RoutingApi::RoutingApiUnavailable
+        end
+
+        it 'returns a 503 and helpful error message' do
+          post '/v3/domains', domain_params.to_json, user_header
+
+          expect(last_response.status).to eq(503)
+          expect(parsed_response['errors'][0]['detail']).to eq 'The Routing API is currently unavailable. Please try again later.'
+        end
+      end
+
+      context 'when the Routing API is disabled' do
+        let(:user_header) { admin_headers_for(user) }
+
+        before do
+          allow(routing_api_client).to receive(:enabled?).and_return false
+        end
+
+        it 'returns a 503 with a helpful message' do
+          post '/v3/domains', domain_params.to_json, user_header
+
+          expect(last_response.status).to eq(503)
+          expect(parsed_response['errors'][0]['detail']).to eq 'The Routing API is disabled.'
+        end
+      end
+
+      context 'when UAA is unavailable' do
+        let(:user_header) { admin_headers_for(user) }
+
+        before do
+          allow(routing_api_client).to receive(:router_group).and_raise VCAP::CloudController::RoutingApi::UaaUnavailable
+        end
+
+        it 'returns a 503 with a helpful message' do
+          post '/v3/domains', domain_params.to_json, user_header
+
+          expect(last_response.status).to eq(503)
+          expect(parsed_response['errors'][0]['detail']).to eq 'Communicating with the Routing API failed because UAA is currently unavailable. Please try again later.'
+        end
+      end
     end
 
     describe 'when creating a private domain' do
@@ -1088,7 +1134,7 @@
           end
         end
 
-        context 'when a router group is provided' do
+        describe 'when a router group is provided' do
           let(:params) do
             {
               name: 'my-domain.biz',

vendor/errors/v2.yml

@@ -98,6 +98,11 @@
   http_code: 429
   message: "Rate Limit Exceeded: Unauthenticated requests from this IP address have exceeded the limit. Please log in."
 
+10015:
+  name: ServiceUnavailable
+  http_code: 503
+  message: "%s"
+
 20001:
   name: UserInvalid
   http_code: 400