--- /dev/null
+<?php
+
+namespace Drupal\migrate_drupal\Plugin\migrate\source;
+
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\State\StateInterface;
+use Drupal\migrate\Plugin\MigrationInterface;
+
+/**
+ * Drupal variable source from database.
+ *
+ * This source class always returns a single row and as such is not a good
+ * example for any normal source class returning multiple rows.
+ *
+ * @MigrateSource(
+ * id = "variable"
+ * )
+ */
+class Variable extends DrupalSqlBase {
+
+ /**
+ * The variable names to fetch.
+ *
+ * @var array
+ */
+ protected $variables;
+
+ /**
+ * {@inheritdoc}
+ */
+ public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, StateInterface $state, EntityManagerInterface $entity_manager) {
+ parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $state, $entity_manager);
+ $this->variables = $this->configuration['variables'];
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function initializeIterator() {
+ return new \ArrayIterator([$this->values()]);
+ }
+
+ /**
+ * Return the values of the variables specified in the plugin configuration.
+ *
+ * @return array
+ * An associative array where the keys are the variables specified in the
+ * plugin configuration and the values are the values found in the source.
+ * Only those values are returned that are actually in the database.
+ */
+ protected function values() {
+ // Create an ID field so we can record migration in the map table.
+ // Arbitrarily, use the first variable name.
+ $values['id'] = reset($this->variables);
+ return $values + array_map('unserialize', $this->prepareQuery()->execute()->fetchAllKeyed());
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function count() {
+ return intval($this->query()->countQuery()->execute()->fetchField() > 0);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function fields() {
+ return array_combine($this->variables, $this->variables);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function query() {
+ return $this->getDatabase()
+ ->select('variable', 'v')
+ ->fields('v', ['name', 'value'])
+ ->condition('name', $this->variables, 'IN');
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getIds() {
+ $ids['id']['type'] = 'string';
+ return $ids;
+ }
+
+}