feat: move SQL connection parameters into Env. vars

docker_dev/compose.yaml

@@ -5,6 +5,11 @@ services:
             dockerfile: docker_dev/Dockerfile
         ports:
             - 8081:80
+        environment:
+          MYSQL_HOST: mysql
+          MYSQL_USER: root
+          MYSQL_PASSWORD: example
+          MYSQL_DATABASE: dragon_fire
         develop:
             watch:
                 - path: ./

www/mysql_adapter.php

@@ -7,7 +7,8 @@ class MySQLAdapter {
 	public $data_directory;
 
 	function __construct() {
-		$this->raw = mysqli_connect('mysql', 'root', 'example', 'dragon_fire');
+		$this->raw = mysqli_connect(getenv('MYSQL_HOST'), 
+			getenv('MYSQL_USER'), getenv('MYSQL_PASSWORD'), getenv('MYSQL_DATABASE'));
 
 		$this->data_directory = 'raw';