Fix database cross-join in ApplicationContext

lib/gitlab/application_context.rb

@@ -124,11 +124,8 @@ module Gitlab
       strong_memoize(:runner_project) do
         next unless runner&.project_type?
 
-        projects = ::Gitlab::Database.allow_cross_joins_across_databases(url: 'https://gitlab.com/gitlab-org/gitlab/-/issues/342147') do
-          runner.projects.take(2) # rubocop: disable CodeReuse/ActiveRecord
-        end
-
-        projects.first if projects.one?
+        runner_projects = runner.runner_projects.take(2) # rubocop: disable CodeReuse/ActiveRecord
+        runner_projects.first.project if runner_projects.one?
       end
     end
 

spec/lib/gitlab/application_context_spec.rb

@@ -152,6 +152,38 @@ RSpec.describe Gitlab::ApplicationContext do
         end
       end
     end
+
+    context 'when using a runner project' do
+      let_it_be_with_reload(:runner) { create(:ci_runner, :project) }
+
+      it 'sets project path from runner project' do
+        context = described_class.new(runner: runner)
+
+        expect(result(context)).to include(project: runner.runner_projects.first.project.full_path)
+      end
+
+      context 'when the runner serves multiple projects' do
+        before do
+          create(:ci_runner_project, runner: runner, project: create(:project))
+        end
+
+        it 'does not set project path' do
+          context = described_class.new(runner: runner)
+
+          expect(result(context)).to include(project: nil)
+        end
+      end
+    end
+
+    context 'when using an instance runner' do
+      let_it_be(:runner) { create(:ci_runner, :instance) }
+
+      it 'does not sets project path' do
+        context = described_class.new(runner: runner)
+
+        expect(result(context)).to include(project: nil)
+      end
+    end
   end
 
   describe '#use' do

spec/requests/api/ci/runner/jobs_request_post_spec.rb

@@ -833,8 +833,8 @@ RSpec.describe API::Ci::Runner, :clean_gitlab_redis_shared_state do
               let(:expected_params) { { project: project.full_path, client_id: "runner/#{runner.id}" } }
             end
 
-            it_behaves_like 'not executing any extra queries for the application context', 2 do
-              # Extra queries: Project, Route
+            it_behaves_like 'not executing any extra queries for the application context', 3 do
+              # Extra queries: Project, Route, RunnerProject
               let(:subject_proc) { proc { request_job } }
             end
           end