Allow edits to applciation settings in maintenance mode

ee/lib/ee/gitlab/middleware/read_only/controller.rb

@@ -51,7 +51,10 @@ module EE
           end
 
           def admin_settings_update?
-            request.path.start_with?('/api/v4/application/settings')
+            return false if ::Gitlab::Geo.secondary?
+
+            request.path.start_with?('/api/v4/application/settings',
+                                     '/admin/application_settings/general')
           end
 
           def geo_node_update_route?

ee/spec/support/shared_examples/lib/gitlab/middleware/maintenance_mode_gitlab_ee_instance_shared_examples.rb

@@ -15,13 +15,20 @@ RSpec.shared_examples 'write access for a read-only GitLab (EE) instance in main
 
     it_behaves_like 'allowlisted /admin/geo requests'
 
-    it "expects a PUT request to /admin/application_settings/general to be allowed" do
+    it "expects a PUT request to /api/v4/application/settings to be allowed" do
       response = request.send(:put, "/api/v4/application/settings")
 
       expect(response).not_to be_redirect
       expect(subject).not_to disallow_request
     end
 
+    it "expects a POST request to /admin/application_settings/general to be allowed" do
+      response = request.send(:post, "/admin/application_settings/general")
+
+      expect(response).not_to be_redirect
+      expect(subject).not_to disallow_request
+    end
+
     context 'on Geo secondary' do
       before do
         allow(::Gitlab::Geo).to receive(:secondary?).and_return(true)
@@ -46,6 +53,7 @@ RSpec.shared_examples 'write access for a read-only GitLab (EE) instance in main
         'LFS request to locks create' | '/root/rouge.git/info/lfs/locks'
         'LFS request to locks unlock' | '/root/rouge.git/info/lfs/locks/1/unlock'
         'git-receive-pack'            | '/root/rouge.git/git-receive-pack'
+        'application settings'        | '/admin/application_settings/general'
       end
 
       with_them do
@@ -56,6 +64,13 @@ RSpec.shared_examples 'write access for a read-only GitLab (EE) instance in main
           expect(subject).to disallow_request
         end
       end
+
+      it "expects a PUT request to /api/v4/application/settings to not be allowed" do
+        response = request.send(:put, "/api/v4/application/settings")
+
+        expect(response).to be_redirect
+        expect(subject).to disallow_request
+      end
     end
 
     context 'when not on Geo secondary' do