drupal/core/modules/rest/rest.install

<?php

/**
 * @file
 * Install, update and uninstall functions for the rest module.
 */

/**
 * Implements hook_requirements().
 */
function rest_requirements($phase) {
  $requirements = array();

  if (version_compare(PHP_VERSION, '5.6.0', '>=') && version_compare(PHP_VERSION, '7', '<') && ini_get('always_populate_raw_post_data') != -1) {
    $requirements['always_populate_raw_post_data'] = array(
      'title' => t('always_populate_raw_post_data PHP setting'),
      'value' => t('Not set to -1.'),
      'severity' => REQUIREMENT_ERROR,
      'description' => t('The always_populate_raw_post_data PHP setting should be set to -1 in PHP version 5.6. Please check the <a href="https://php.net/manual/en/ini.core.php#ini.always-populate-raw-post-data">PHP manual</a> for information on how to correct this.'),
    );
  }
  return $requirements;
}

/**
 * @defgroup updates-8.1.x-to-8.2.x
 * @{
 * Update functions from 8.1.x to 8.2.x.
 */

/**
 * Install the REST config entity type and fix old settings-based config.
 *
 * @see rest_post_update_create_rest_resource_config_entities()
 */
function rest_update_8201() {
  \Drupal::entityDefinitionUpdateManager()->installEntityType(\Drupal::entityTypeManager()->getDefinition('rest_resource_config'));
  \Drupal::state()->set('rest_update_8201_resources', \Drupal::config('rest.settings')->get('resources'));
  \Drupal::configFactory()->getEditable('rest.settings')
    ->clear('resources')
    ->save();
}

/**
 * Re-save all views with a REST display to add new auth defaults.
 */
function rest_update_8202() {
  $config_factory = \Drupal::configFactory();
  foreach ($config_factory->listAll('views.view.') as $view_config_name) {
    $save = FALSE;
    $view = $config_factory->getEditable($view_config_name);
    $displays = $view->get('display');
    foreach ($displays as $display_name => &$display) {
      if ($display['display_plugin'] == 'rest_export') {
        if (!isset($display['display_options']['auth'])) {
          $display['display_options']['auth'] = [];
          $save = TRUE;
        }
      }
    }
    if ($save) {
      $view->set('display', $displays);
      $view->save(TRUE);
    }
  }
}

/**
 * Enable BC for EntityResource: continue to use permissions.
 */
function rest_update_8203() {
  $config_factory = \Drupal::configFactory();
  $rest_settings = $config_factory->getEditable('rest.settings');
  $rest_settings->set('bc_entity_resource_permissions', TRUE)
    ->save(TRUE);
}

/**
 * @} End of "defgroup updates-8.1.x-to-8.2.x".
 */