Add future_subscriptions column

This is for self-managed EE to store an array of JSON objects.
ApplicationSetting is used instead of a new table because this will be
overwritten during each sync, and won't be updated.

There will ever store a handful of items and are displayed as a whole.

Changelog: added

db/migrate/20211201061733_add_future_subscriptions_to_application_settings.rb

+# frozen_string_literal: true
+
+class AddFutureSubscriptionsToApplicationSettings < Gitlab::Database::Migration[1.0]
+  def change
+    add_column :application_settings, :future_subscriptions, :jsonb, null: false, default: []
+  end
+end

db/schema_migrations/20211201061733

+c5282e48f31c0896a3ce21fe238eb602dc006b0bfe62aa4f12ee39bbd620c76c
\ No newline at end of file

db/structure.sql

@@ -10479,6 +10479,7 @@ CREATE TABLE application_settings (
     sentry_environment text,
     max_ssh_key_lifetime integer,
     static_objects_external_storage_auth_token_encrypted text,
+    future_subscriptions jsonb DEFAULT '[]'::jsonb NOT NULL,
     CONSTRAINT app_settings_container_reg_cleanup_tags_max_list_size_positive CHECK ((container_registry_cleanup_tags_service_max_list_size >= 0)),
     CONSTRAINT app_settings_dep_proxy_ttl_policies_worker_capacity_positive CHECK ((dependency_proxy_ttl_group_policy_worker_capacity >= 0)),
     CONSTRAINT app_settings_ext_pipeline_validation_service_url_text_limit CHECK ((char_length(external_pipeline_validation_service_url) <= 255)),

ee/app/models/ee/application_setting.rb

@@ -90,6 +90,8 @@ module EE
                 allow_blank: true,
                 length: { maximum: EMAIL_ADDITIONAL_TEXT_CHARACTER_LIMIT }
 
+      validates :future_subscriptions, json_schema: { filename: 'future_subscriptions' }
+
       validates :geo_node_allowed_ips, length: { maximum: 255 }, presence: true
 
       validates :required_instance_ci_template, presence: true, allow_nil: true
@@ -124,6 +126,8 @@ module EE
 
       after_commit :update_personal_access_tokens_lifetime, if: :saved_change_to_max_personal_access_token_lifetime?
       after_commit :resume_elasticsearch_indexing
+
+      serialize :future_subscriptions, Serializers::Json # rubocop:disable Cop/ActiveRecordSerialize
     end
 
     class_methods do
@@ -154,6 +158,7 @@ module EE
           email_additional_text: nil,
           enforce_namespace_storage_limit: false,
           enforce_pat_expiration: true,
+          future_subscriptions: [],
           geo_node_allowed_ips: '0.0.0.0/0, ::/0',
           git_two_factor_session_expiry: 15,
           lock_memberships_to_ldap: false,

ee/app/validators/json_schemas/future_subscriptions.json

+{
+  "description": "A list of future subscriptions",
+  "type": "array",
+  "items": {
+    "type": "object"
+  },
+  "maxItems": 100
+}

ee/app/workers/sync_seat_link_request_worker.rb

@@ -28,6 +28,7 @@ class SyncSeatLinkRequestWorker
     if response.success?
       reset_license!(response['license']) if response['license']
 
+      save_future_subscriptions(response)
       save_reconciliation_dates!(response)
     else
       raise RequestError, request_error_message(response)
@@ -77,4 +78,12 @@ class SyncSeatLinkRequestWorker
       GitlabSubscriptions::UpcomingReconciliation.create!(attributes)
     end
   end
+
+  def save_future_subscriptions(response)
+    return if response['future_subscriptions'].blank?
+
+    Gitlab::CurrentSettings.current_application_settings.update!(future_subscriptions: response['future_subscriptions'])
+  rescue StandardError => err
+    Gitlab::ErrorTracking.track_and_raise_for_dev_exception(err)
+  end
 end

ee/spec/models/application_setting_spec.rb

@@ -63,6 +63,10 @@ RSpec.describe ApplicationSetting do
     it { is_expected.to allow_value('a' * 255).for(:elasticsearch_username) }
     it { is_expected.not_to allow_value('a' * 256).for(:elasticsearch_username) }
 
+    it { is_expected.to allow_value([{}]).for(:future_subscriptions) }
+    it { is_expected.not_to allow_value({}).for(:future_subscriptions) }
+    it { is_expected.not_to allow_value(nil).for(:future_subscriptions) }
+
     it { is_expected.to allow_value(nil).for(:required_instance_ci_template) }
     it { is_expected.not_to allow_value("").for(:required_instance_ci_template) }
     it { is_expected.not_to allow_value("  ").for(:required_instance_ci_template) }

ee/spec/workers/sync_seat_link_request_worker_spec.rb

@@ -158,6 +158,45 @@ RSpec.describe SyncSeatLinkRequestWorker, type: :worker do
       end
     end
 
+    context 'when response contains future subscription information' do
+      let(:future_subscriptions) { [{ 'foo' => 'bar' }] }
+      let(:body) { { success: true, future_subscriptions: future_subscriptions }.to_json }
+      let(:today) { Date.current }
+
+      before do
+        stub_request(:post, seat_link_url).to_return(
+          status: 200,
+          body: body,
+          headers: { content_type: 'application/json' }
+        )
+      end
+
+      it 'persists future subscription information' do
+        expect { sync_seat_link }.to change { Gitlab::CurrentSettings.current_application_settings.future_subscriptions }.from([]).to(future_subscriptions)
+      end
+
+      context 'when future subscription is empty' do
+        let(:future_subscriptions) { [] }
+
+        before do
+          Gitlab::CurrentSettings.current_application_settings.update!(future_subscriptions: [{}])
+        end
+
+        it 'does nothing' do
+          expect { sync_seat_link }.not_to change { Gitlab::CurrentSettings.current_application_settings.future_subscriptions }.from([{}])
+        end
+      end
+
+      context 'when saving fails' do
+        it 'logs error' do
+          allow(Gitlab::CurrentSettings.current_application_settings).to receive(:save!).and_raise('saving fails')
+
+          expect(Gitlab::ErrorTracking).to receive(:track_and_raise_for_dev_exception)
+          expect { sync_seat_link }.not_to raise_error
+        end
+      end
+    end
+
     shared_examples 'unsuccessful request' do
       context 'when the request is not successful' do
         before do