Issue #1824834 by vijaycs85, Albert Volkman: Covert default_nodes_main() variable to CMI system.

core/modules/node/config/node.settings.yml

+items_per_page: '10'

core/modules/node/node.install

@@ -489,7 +489,6 @@ function node_uninstall() {
   variable_del('node_admin_theme');
   variable_del('node_cron_last');
   variable_del('node_recent_block_count');
-  variable_del('default_nodes_main');
 }
 
 /**
@@ -711,6 +710,15 @@ function node_update_8008() {
   }
 }
 
+/**
+ * Coverts default_nodes_main variable to config.
+ *
+ * @ingroup config_upgrade
+ */
+function node_update_8009() {
+  update_variables_to_config('node.settings', array('default_nodes_main' => 'items_per_page'));
+}
+
 /**
  * @} End of "addtogroup updates-7.x-to-8.x"
  * The next series of updates should start at 9000.

core/modules/node/node.module

@@ -2369,7 +2369,7 @@ function node_page_default() {
     ->orderBy('n.sticky', 'DESC')
     ->orderBy('n.created', 'DESC')
     ->extend('Drupal\Core\Database\Query\PagerSelectExtender')
-    ->limit(variable_get('default_nodes_main', 10))
+    ->limit(config('node.settings')->get('items_per_page'))
     ->addTag('node_access');
 
   $nids = $select->execute()->fetchCol();
@@ -2624,7 +2624,7 @@ function node_form_system_site_information_settings_form_alter(&$form, &$form_st
   $form['front_page']['default_nodes_main'] = array(
     '#type' => 'select',
     '#title' => t('Number of posts on front page'),
-    '#default_value' => variable_get('default_nodes_main', 10),
+    '#default_value' => config('node.settings')->get('items_per_page'),
     '#options' => drupal_map_assoc(array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30)),
     '#access' => (config('system.site')->get('page.front') == 'node'),
     '#description' => t('The maximum number of posts displayed on overview pages such as the front page.'),
@@ -2638,7 +2638,9 @@ function node_form_system_site_information_settings_form_alter(&$form, &$form_st
  * @see node_form_system_site_information_settings_form_alter()
  */
 function node_form_system_site_information_settings_form_submit($form, &$form_state) {
-  variable_set('default_nodes_main', $form_state['values']['default_nodes_main']);
+  config('node.settings')
+    ->set('items_per_page', $form_state['values']['default_nodes_main'])
+    ->save();
 }
 
 /**

core/modules/taxonomy/taxonomy.pages.inc

@@ -46,7 +46,7 @@ function taxonomy_term_page(Term $term) {
   drupal_add_html_head_link(array('rel' => 'shortlink', 'href' => url($uri['path'], array_merge($uri['options'], array('alias' => TRUE)))), TRUE);
 
   $build['taxonomy_terms'] = taxonomy_term_view_multiple(array($term->id() => $term));
-  if ($nids = taxonomy_select_nodes($term->tid, TRUE, variable_get('default_nodes_main', 10))) {
+  if ($nids = taxonomy_select_nodes($term->tid, TRUE, config('node.settings')->get('items_per_page'))) {
     $nodes = node_load_multiple($nids);
     $build['nodes'] = node_view_multiple($nodes);
     $build['pager'] = array(