added db healtcheck console command

console/controllers/HealthcheckController.php

@@ -0,0 +1,51 @@
+<?php
+namespace console\controllers;
+
+use Yii;
+use yii\console\Controller;
+use yii\helpers\Console;
+
+/**
+ * @author Gani Georgiev <gani.georgiev@gmail.com>
+ */
+class HealthcheckController extends Controller
+{
+    /**
+     * @inheritdoc
+     */
+    public $color = true;
+
+    /**
+     * Checks whether the DB connection is established.
+     *
+     * @example
+     * ```bash
+     * php yii healthcheck/db
+     * ```
+     *
+     * @return integer
+     */
+    public function actionDb()
+    {
+        try {
+            Yii::$app->db->open();
+
+            if (Yii::$app->db->isActive) {
+                $this->stdout('DB connection is established.', Console::FG_GREEN);
+                $this->stdout(PHP_EOL);
+
+                Yii::$app->db->close();
+
+                return self::EXIT_CODE_NORMAL;
+            }
+        } catch (\Exception $e) {
+            $this->stdout($e->getMessage(), Console::FG_RED);
+            $this->stdout(PHP_EOL);
+        }
+
+        $this->stdout('Cannot connect to DB.', Console::BG_RED);
+        $this->stdout(PHP_EOL);
+
+        return self::EXIT_CODE_ERROR;
+    }
+}