Remove runners <-> groups cross-joins where possible

app/models/ci/runner.rb

@@ -438,10 +438,8 @@ module Ci
     end
 
     def no_groups
-      ::Gitlab::Database.allow_cross_joins_across_databases(url: 'https://gitlab.com/gitlab-org/gitlab/-/issues/338659') do
-        if groups.any?
-          errors.add(:runner, 'cannot have groups assigned')
-        end
+      if runner_namespaces.any?
+        errors.add(:runner, 'cannot have groups assigned')
       end
     end
 
@@ -452,10 +450,8 @@ module Ci
     end
 
     def exactly_one_group
-      ::Gitlab::Database.allow_cross_joins_across_databases(url: 'https://gitlab.com/gitlab-org/gitlab/-/issues/338659') do
-        unless groups.one?
-          errors.add(:runner, 'needs to be assigned to exactly one group')
-        end
+      unless runner_namespaces.one?
+        errors.add(:runner, 'needs to be assigned to exactly one group')
       end
     end
 

app/models/clusters/applications/runner.rb

@@ -70,7 +70,7 @@ module Clusters
         }
 
         if cluster.group_type?
-          attributes[:groups] = [group]
+          attributes[:runner_namespaces] = [::Ci::RunnerNamespace.new(namespace: group)]
         elsif cluster.project_type?
           attributes[:runner_projects] = [::Ci::RunnerProject.new(project: project)]
         end

spec/factories/ci/runner_namespaces.rb

@@ -2,7 +2,14 @@
 
 FactoryBot.define do
   factory :ci_runner_namespace, class: 'Ci::RunnerNamespace' do
-    runner factory: [:ci_runner, :group]
     group
+
+    after(:build) do |runner_namespace, evaluator|
+      unless runner_namespace.runner.present?
+        runner_namespace.runner = build(
+          :ci_runner, :group, runner_namespaces: [runner_namespace]
+        )
+      end
+    end
   end
 end

spec/factories/ci/runners.rb

@@ -11,6 +11,7 @@ FactoryBot.define do
     runner_type { :instance_type }
 
     transient do
+      groups { [] }
       projects { [] }
     end
 
@@ -18,6 +19,10 @@ FactoryBot.define do
       evaluator.projects.each do |proj|
         runner.runner_projects << build(:ci_runner_project, project: proj)
       end
+
+      evaluator.groups.each do |group|
+        runner.runner_namespaces << build(:ci_runner_namespace, namespace: group)
+      end
     end
 
     trait :online do
@@ -32,7 +37,9 @@ FactoryBot.define do
       runner_type { :group_type }
 
       after(:build) do |runner, evaluator|
-        runner.groups << build(:group) if runner.groups.empty?
+        if runner.runner_namespaces.empty?
+          runner.runner_namespaces << build(:ci_runner_namespace)
+        end
       end
     end
 

spec/models/ci/runner_spec.rb

@@ -44,7 +44,7 @@ RSpec.describe Ci::Runner do
       let(:runner) { create(:ci_runner, :group, groups: [group]) }
 
       it 'disallows assigning group if already assigned to a group' do
-        runner.groups << build(:group)
+        runner.runner_namespaces << build(:ci_runner_namespace)
 
         expect(runner).not_to be_valid
         expect(runner.errors.full_messages).to include('Runner needs to be assigned to exactly one group')

spec/models/clusters/applications/runner_spec.rb

@@ -112,7 +112,7 @@ RSpec.describe Clusters::Applications::Runner do
           subject
 
           expect(runner).to be_group_type
-          expect(runner.groups).to eq [group]
+          expect(runner.runner_namespaces.pluck(:namespace_id)).to match_array [group.id]
         end
       end