Fix GraphQL for read-only instances with relative URLs

Geo Nodes with relative URL should also allow graphql querues

ee/changelogs/unreleased/233104-when-relative-url-is-configured-on-secondary-the-requests-to-ap.yml

+---
+title: Fix GraphQL for read-only instances with relative URLs
+merge_request: 38402
+author:
+type: fixed

lib/gitlab/middleware/read_only/controller.rb

@@ -136,7 +136,7 @@ module Gitlab
         end
 
         def graphql_query?
-          request.post? && request.path.start_with?(GRAPHQL_URL)
+          request.post? && request.path.start_with?(File.join(relative_url, GRAPHQL_URL))
         end
       end
     end

spec/lib/gitlab/middleware/read_only_spec.rb

@@ -110,6 +110,19 @@ RSpec.describe Gitlab::Middleware::ReadOnly do
         expect(subject).not_to disallow_request
       end
 
+      context 'relative URL is configured' do
+        before do
+          stub_config_setting(relative_url_root: '/gitlab')
+        end
+
+        it 'expects a graphql request to be allowed' do
+          response = request.post("/gitlab/api/graphql")
+
+          expect(response).not_to be_redirect
+          expect(subject).not_to disallow_request
+        end
+      end
+
       context 'sidekiq admin requests' do
         where(:mounted_at) do
           [