Merge branch '349737-add-test-for-no-new-cross-db-foreign-keys' into 'master'

Add spec to validate we do not add more cross-database foreign keys

See merge request gitlab-org/gitlab!77732

spec/lib/gitlab/database/no_cross_db_foreign_keys_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'cross-database foreign keys' do
+  # TODO: We are trying to empty out this list in
+  # https://gitlab.com/groups/gitlab-org/-/epics/7249 . Once we are done we can
+  # keep this test and assert that there are no cross-db foreign keys. We
+  # should not be adding anything to this list but should instead only add new
+  # loose foreign keys
+  # https://docs.gitlab.com/ee/development/database/loose_foreign_keys.html .
+  let(:allowed_cross_database_foreign_keys) do
+    %w(
+      ci_build_report_results.project_id
+      ci_builds.project_id
+      ci_builds_metadata.project_id
+      ci_daily_build_group_report_results.group_id
+      ci_daily_build_group_report_results.project_id
+      ci_freeze_periods.project_id
+      ci_job_artifacts.project_id
+      ci_job_token_project_scope_links.added_by_id
+      ci_job_token_project_scope_links.source_project_id
+      ci_job_token_project_scope_links.target_project_id
+      ci_pending_builds.namespace_id
+      ci_pending_builds.project_id
+      ci_pipeline_artifacts.project_id
+      ci_pipeline_schedules.owner_id
+      ci_pipeline_schedules.project_id
+      ci_pipelines.merge_request_id
+      ci_pipelines.project_id
+      ci_project_monthly_usages.project_id
+      ci_refs.project_id
+      ci_resource_groups.project_id
+      ci_runner_namespaces.namespace_id
+      ci_runner_projects.project_id
+      ci_running_builds.project_id
+      ci_sources_pipelines.project_id
+      ci_sources_pipelines.source_project_id
+      ci_sources_projects.source_project_id
+      ci_stages.project_id
+      ci_subscriptions_projects.downstream_project_id
+      ci_subscriptions_projects.upstream_project_id
+      ci_triggers.owner_id
+      ci_triggers.project_id
+      ci_unit_tests.project_id
+      ci_variables.project_id
+      dast_profiles_pipelines.ci_pipeline_id
+      dast_scanner_profiles_builds.ci_build_id
+      dast_site_profiles_builds.ci_build_id
+      dast_site_profiles_pipelines.ci_pipeline_id
+      external_pull_requests.project_id
+      merge_requests.head_pipeline_id
+      merge_trains.pipeline_id
+      requirements_management_test_reports.build_id
+      security_scans.build_id
+      vulnerability_feedback.pipeline_id
+      vulnerability_occurrence_pipelines.pipeline_id
+      vulnerability_statistics.latest_pipeline_id
+    ).freeze
+  end
+
+  def foreign_keys_for(table_name)
+    ApplicationRecord.connection.foreign_keys(table_name)
+  end
+
+  def is_cross_db?(fk_record)
+    Gitlab::Database::GitlabSchema.table_schemas([fk_record.from_table, fk_record.to_table]).many?
+  end
+
+  it 'onlies have allowed list of cross-database foreign keys', :aggregate_failures do
+    all_tables = ApplicationRecord.connection.data_sources
+
+    all_tables.each do |table|
+      foreign_keys_for(table).each do |fk|
+        if is_cross_db?(fk)
+          column = "#{fk.from_table}.#{fk.column}"
+          expect(allowed_cross_database_foreign_keys).to include(column), "Found extra cross-database foreign key #{column} referencing #{fk.to_table} with constraint name #{fk.name}. When a foreign key references another database you must use a Loose Foreign Key instead https://docs.gitlab.com/ee/development/database/loose_foreign_keys.html ."
+        end
+      end
+    end
+  end
+end