Allow Projects with Freeze Periods to be Deleted

The original creation of the foreign key from freeze periods to projects
did not set any on delete behaviour.

The migration here deletes and recreates that foreign key with a
cascading on delete, allowing the project delete to also delete any
linked freeze periods.

Changelog: fixed

db/migrate/20210617161348_cascade_delete_freeze_periods.rb

+# frozen_string_literal: true
+
+# See https://docs.gitlab.com/ee/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class CascadeDeleteFreezePeriods < ActiveRecord::Migration[6.1]
+  include Gitlab::Database::MigrationHelpers
+
+  OLD_PROJECT_FK = 'fk_rails_2e02bbd1a6'
+  NEW_PROJECT_FK = 'fk_2e02bbd1a6'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_foreign_key :ci_freeze_periods, :projects, column: :project_id, on_delete: :cascade, name: NEW_PROJECT_FK
+    remove_foreign_key_if_exists :ci_freeze_periods, :projects, column: :project_id, name: OLD_PROJECT_FK
+  end
+
+  def down
+    add_concurrent_foreign_key :ci_freeze_periods, :projects, column: :project_id, on_delete: nil, name: OLD_PROJECT_FK
+    remove_foreign_key_if_exists :ci_freeze_periods, :projects, column: :project_id, name: NEW_PROJECT_FK
+  end
+end

db/schema_migrations/20210617161348

+3f73aa7d2cff11d00b330d88e76daaa058f82b7012da3c244f246da6e538921c
\ No newline at end of file

db/structure.sql

@@ -25627,6 +25627,9 @@ ALTER TABLE ONLY geo_event_log
 ALTER TABLE ONLY deployments
     ADD CONSTRAINT fk_289bba3222 FOREIGN KEY (cluster_id) REFERENCES clusters(id) ON DELETE SET NULL;
 
+ALTER TABLE ONLY ci_freeze_periods
+    ADD CONSTRAINT fk_2e02bbd1a6 FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE;
+
 ALTER TABLE ONLY notes
     ADD CONSTRAINT fk_2e82291620 FOREIGN KEY (review_id) REFERENCES reviews(id) ON DELETE SET NULL;
 
@@ -26575,9 +26578,6 @@ ALTER TABLE ONLY onboarding_progresses
 ALTER TABLE ONLY protected_branch_unprotect_access_levels
     ADD CONSTRAINT fk_rails_2d2aba21ef FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE;
 
-ALTER TABLE ONLY ci_freeze_periods
-    ADD CONSTRAINT fk_rails_2e02bbd1a6 FOREIGN KEY (project_id) REFERENCES projects(id);
-
 ALTER TABLE ONLY issuable_severities
     ADD CONSTRAINT fk_rails_2fbb74ad6d FOREIGN KEY (issue_id) REFERENCES issues(id) ON DELETE CASCADE;
 

spec/migrations/2021061716138_cascade_delete_freeze_periods_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+require_migration!('cascade_delete_freeze_periods')
+
+RSpec.describe CascadeDeleteFreezePeriods do
+  let(:namespace) { table(:namespaces).create!(name: 'deploy_freeze', path: 'deploy_freeze') }
+  let(:project) { table(:projects).create!(id: 1, namespace_id: namespace.id) }
+  let(:freeze_periods) { table(:ci_freeze_periods) }
+
+  describe "#up" do
+    it 'allows for a project to be deleted' do
+      freeze_periods.create!(id: 1, project_id: project.id, freeze_start: '5 * * * *', freeze_end: '6 * * * *', cron_timezone: 'UTC')
+      migrate!
+
+      project.delete
+
+      expect(freeze_periods.where(project_id: project.id).count).to be_zero
+    end
+  end
+end