Expose instance AutoDevOps domain in Project

app/models/project.rb

@@ -1604,7 +1604,15 @@ class Project < ActiveRecord::Base
   def auto_devops_variables
     return [] unless auto_devops_enabled?
 
-    auto_devops&.variables || []
+    variables = []
+
+    if current_application_settings.auto_devops_domain.present?
+      variables << { key: 'AUTO_DEVOPS_DOMAIN',
+                     value: current_application_settings.auto_devops_domain,
+                     public: true }
+    end
+
+    auto_devops&.variables || variables
   end
 
   def append_or_update_attribute(name, value)

spec/models/project_spec.rb

@@ -2976,18 +2976,40 @@ describe Project do
 
     subject { project.auto_devops_variables }
 
-    context 'when enabled in settings' do
+    context 'when enabled in instance settings' do
       before do
         stub_application_setting(auto_devops_enabled: true)
       end
 
+      context 'when domain is empty' do
+        before do
+          stub_application_setting(auto_devops_domain: nil)
+        end
+
+        it 'variables does not include AUTO_DEVOPS_DOMAIN' do
+          is_expected.not_to include(domain_variable)
+        end
+      end
+
+      context 'when domain is configured' do
+        before do
+          stub_application_setting(auto_devops_domain: 'example.com')
+        end
+
+        it 'variables includes AUTO_DEVOPS_DOMAIN' do
+          is_expected.to include(domain_variable)
+        end
+      end
+    end
+
+    context 'when explicitely enabled' do
       context 'when domain is empty' do
         before do
           create(:project_auto_devops, project: project, domain: nil)
         end
 
-        it 'variables are empty' do
+        it 'variables does not include AUTO_DEVOPS_DOMAIN' do
-          is_expected.to be_empty
+          is_expected.not_to include(domain_variable)
         end
       end
 
@@ -2996,11 +3018,15 @@ describe Project do
           create(:project_auto_devops, project: project, domain: 'example.com')
         end
 
-        it "variables are not empty" do
+        it 'variables includes AUTO_DEVOPS_DOMAIN' do
-          is_expected.not_to be_empty
+          is_expected.to include(domain_variable)
         end
       end
     end
+
+    def domain_variable
+      { key: 'AUTO_DEVOPS_DOMAIN', value: 'example.com', public: true }
+    end
   end
 
   describe '#latest_successful_builds_for' do