Convert update settings to configuration system

+++ b/core/modules/update/config/update.settings.yml

The indentation for nested keys should be 4 spaces... :-/

+++ b/core/modules/update/config/update.settings.yml
@@ -0,0 +1,12 @@
+  fetch_url: ''
...
+  max_fetch_attempts: '2'
+  max_fetch_time: '5'

Would it make sense to put all the fetch settings into a separate 'fetch' key on the top-level? E.g.:

fetch:
    url: ''
    max_attempts: '2'
    timeout: '5'

+++ b/core/modules/update/config/update.settings.yml
@@ -0,0 +1,12 @@
+  disabled: '0'

+++ b/core/modules/update/update.settings.inc
@@ -27,22 +28,22 @@ function update_settings($form) {
     '#title' => t('Check for updates of disabled modules and themes'),
...
+    '#default_value' => $config->get('check.disabled'),

Wow, I was horribly mistaken when I first saw this key and wanted to suggest to change it into 'enabled'...

Let's rename this into 'check.disabled_extensions'

+++ b/core/modules/update/config/update.settings.yml
@@ -0,0 +1,12 @@
+  frequency: '1'

+++ b/core/modules/update/update.fetch.inc
@@ -177,7 +178,7 @@ function _update_process_fetch_task($project) {
+  $frequency = $update_config->get('check.frequency');
   $cid = 'available_releases::' . $project_name;
   _update_cache_set($cid, $available, $now + (60 * 60 * 24 * $frequency));

I had to look up what this key means. Possible alternatives:

check.interval
check.interval_days
check.expire
check.expire_days

All not really ideal, better suggestions welcome.

+++ b/core/modules/update/config/update.settings.yml
@@ -0,0 +1,12 @@
+  emails: {}

+++ b/core/modules/update/update.fetch.inc
@@ -353,7 +357,7 @@ function _update_cron_notify() {
+    $notify_list = $update_config->get('notification.emails');
...
       foreach ($notify_list as $target) {

This seems to be a simple array, so the empty syntax is []

+++ b/core/modules/update/update.fetch.inc
@@ -185,7 +186,7 @@ function _update_process_fetch_task($project) {
   // Whether this worked or not, we did just (try to) check for updates.
-  variable_set('update_last_check', $now);
+  $update_config->set('check.executed', $now)->save();

This variable is "state", not configuration, and thus we should leave it alone.

+++ b/core/modules/update/update.fetch.inc
@@ -328,7 +329,9 @@ function _update_build_fetch_url($project, $site_key = '') {
 function _update_get_fetch_url_base($project) {
-  return isset($project['info']['project status url']) ? $project['info']['project status url'] : variable_get('update_fetch_url', UPDATE_DEFAULT_URL);
+  $config_url = config('update.settings')->get('check.fetch_url');
+  $default_url = !empty($config_url) ? $config_url : UPDATE_DEFAULT_URL;
+  return isset($project['info']['project status url']) ? $project['info']['project status url'] : $default_url;

Let's use a if/else control structure instead of the ternary operator here, so we do not need to load the config object if $project contains a URL already.

+++ b/core/modules/update/update.settings.inc
@@ -12,11 +12,12 @@
+function update_settings($form, $form_state) {

&$form_state always needs to be taken by reference.

+++ b/core/modules/update/update.settings.inc
@@ -106,23 +101,21 @@ function update_settings_validate($form, &$form_state) {
 function update_settings_submit($form, $form_state) {
...
+
+  unset($form_state['notify_emails']);
+  unset($form_state['values']['update_notify_emails']);

I do not understand why this was added? Can we revert it? :)

+++ b/core/includes/update.inc
@@ -345,9 +345,10 @@ function update_module_add_to_system($modules = array()) {
 function update_fix_d8_requirements() {
...
-  if (drupal_get_installed_schema_version('system') < 8000 && !variable_get('update_d8_requirements', FALSE)) {
+  $update_config = config('update.settings');
+  if (drupal_get_installed_schema_version('system') < 8000 && !$update_config->get('d8_requirements')) {
     // @todo: Make critical, first-run changes to the database here.
-    variable_set('update_d8_requirements', TRUE);
+    $update_config->get('d8_requirements', TRUE)->save();
   }

Unfortunately, I overlooked this... this is also state, and/or something we need to resolve differently... let's just revert all the affected code back to variables... :-/

+++ b/core/modules/system/tests/modules/update_script_test/config/update_script_test.settings.yml
@@ -0,0 +1 @@
\ No newline at end of file

+++ b/core/modules/update/tests/modules/update_test/config/update_test.settings.yml
@@ -0,0 +1,3 @@
\ No newline at end of file

...

+++ b/core/modules/update/config/update.settings.yml
@@ -0,0 +1,12 @@
+advanced_project_settings: {}

+++ b/core/modules/update/update.api.php
@@ -83,7 +83,7 @@ function hook_update_projects_alter(&$projects) {
 function hook_update_status_alter(&$projects) {
-  $settings = variable_get('update_advanced_project_settings', array());
+  $settings = config('update.settings')->get('advanced_project_settings');

oh! This key doesn't really exist -- the code you've changed belongs to an example hook implementation in the API documentation for Update module. Let's remove the key from the config file, but keep the change to the example hook code :)

Excellent work. Almost done!

+++ b/core/modules/update/update.install
@@ -77,20 +77,6 @@ function update_install() {
-    'update_last_check',
-    'update_last_email_notification',

We need to re-introduce two variable_del()s for these two state variables. Ideally, along with a

// @todo D8: Convert to new state storage.

Great patch! Couple of minor nitpicks...

+++ b/core/modules/update/tests/modules/update_test/update_test.moduleundefined
@@ -42,7 +42,7 @@ function update_test_menu() {
 /**
  * Implements hook_system_info_alter().
  *
- * Checks the 'update_test_system_info' variable and sees if we need to alter
+ * Checks the 'system_info' setting and sees if we need to alter
  * the system info for the given $file based on the setting. The setting is
  * expected to be a nested associative array. If the key '#all' is defined, its
  * subarray will include .info keys and values for all modules and themes on the

This comment needs to be re-jigged so that each line uses as much of the 80 chars as possible and it should say "Checks the 'update_test.settings:system_info' configuration and..."

+++ b/core/modules/update/tests/modules/update_test/update_test.moduleundefined
@@ -64,7 +64,7 @@ function update_test_system_info_alter(&$info, $file) {
 /**
  * Implements hook_update_status_alter().
  *
- * Checks the 'update_test_update_status' variable and sees if we need to alter
+ * Checks the 'update_status' setting and sees if we need to alter
  * the update status for the given project based on the setting. The setting is
  * expected to be a nested associative array. If the key '#all' is defined, its

As above

+++ b/core/modules/update/tests/modules/update_test/update_test.moduleundefined
@@ -42,13 +42,13 @@
+ * theme short name ($file->name) and the subarrays contain settings just for ¶

trailing whitespace

+++ b/core/modules/update/tests/modules/update_test/update_test.moduleundefined
@@ -64,12 +64,13 @@
+ * is defined, its subarray will include .info keys and values for all modules ¶

trailing whitespace

Almost every text editor/ide has options to trim trailing whitespaces on save. It makes your life easier ;)

26 days to next Drupal core point release.

99.9% done! :)

+++ b/core/modules/update/update.install
@@ -157,3 +147,19 @@ function _update_requirement_check($project, $type) {
+function update_update_8000() {
+  update_variables_to_config('update.settings', array(
+    'update_advanced_project_settings' => 'advanced_project_settings',

Let's also remove the variable of the example hook implementation from the module update :)

Awesome!

Committed to 8.x, including the .yml file. Win! :-)

Thanks everyone.