Swap FK ci_variables to projects for LFK

Swaps FK for ci_variables.project_id to projects

Changelog: changed

db/post_migrate/20220121221651_remove_projects_ci_variables_project_id_fk.rb

+# frozen_string_literal: true
+
+class RemoveProjectsCiVariablesProjectIdFk < Gitlab::Database::Migration[1.0]
+  disable_ddl_transaction!
+
+  def up
+    return unless foreign_key_exists?(:ci_variables, :projects, name: "fk_ada5eb64b3")
+
+    with_lock_retries do
+      execute('LOCK projects, ci_variables IN ACCESS EXCLUSIVE MODE') if transaction_open?
+
+      remove_foreign_key_if_exists(:ci_variables, :projects, name: "fk_ada5eb64b3")
+    end
+  end
+
+  def down
+    add_concurrent_foreign_key(:ci_variables, :projects, name: "fk_ada5eb64b3", column: :project_id, target_column: :id, on_delete: :cascade)
+  end
+end

db/schema_migrations/20220121221651

+a1681c1c619db7f4e7e5a760cee7d06a931aa1f02dccfce46be81d75a03ce8ac
\ No newline at end of file

db/structure.sql

@@ -29696,9 +29696,6 @@ ALTER TABLE ONLY member_tasks
 ALTER TABLE ONLY merge_requests
     ADD CONSTRAINT fk_ad525e1f87 FOREIGN KEY (merge_user_id) REFERENCES users(id) ON DELETE SET NULL;
 
-ALTER TABLE ONLY ci_variables
-    ADD CONSTRAINT fk_ada5eb64b3 FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE;
-
 ALTER TABLE ONLY merge_request_metrics
     ADD CONSTRAINT fk_ae440388cc FOREIGN KEY (latest_closed_by_id) REFERENCES users(id) ON DELETE SET NULL;
 

lib/gitlab/database/gitlab_loose_foreign_keys.yml

@@ -27,6 +27,10 @@ clusters_applications_runners:
   - table: ci_runners
     column: runner_id
     on_delete: async_nullify
+ci_variables:
+  - table: projects
+    column: project_id
+    on_delete: async_delete
 ci_job_token_project_scope_links:
   - table: users
     column: added_by_id

spec/lib/gitlab/database/no_cross_db_foreign_keys_spec.rb

@@ -40,7 +40,6 @@ RSpec.describe 'cross-database foreign keys' do
       ci_subscriptions_projects.upstream_project_id
       ci_triggers.project_id
       ci_unit_tests.project_id
-      ci_variables.project_id
       dast_site_profiles_pipelines.ci_pipeline_id
       external_pull_requests.project_id
       vulnerability_feedback.pipeline_id

spec/models/ci/variable_spec.rb

@@ -44,4 +44,11 @@ RSpec.describe Ci::Variable do
       end
     end
   end
+
+  context 'loose foreign key on ci_variables.project_id' do
+    it_behaves_like 'cleanup by a loose foreign key' do
+      let!(:parent) { create(:project) }
+      let!(:model) { create(:ci_variable, project: parent) }
+    end
+  end
 end