我尝试使用以下步骤在MAC上为apache2（MAMP）设置清漆

**步骤1.**准备安装清漆
**第2步。**已安装Varnished，然后配置为默认值.vcl

backend default {
    .host = "localhost";
    .port = "80";
    .first_byte_timeout = 600s;
    .probe = {
        .url = "/pub/health_check.php";
        .timeout = 2s;
        .interval = 5s;
        .window = 10;
        .threshold = 5;
   }
}

**步骤3.**配置apache2在端口8080上运行

NameVirtualHost *:8080

<VirtualHost *:8080>

</virtualHost>

**步骤4.**运行127.0.0.1或本地主机时给予以下错误

Error 503 Backend fetch failed
Backend fetch failed

Guru Meditation:
XID: 20

Varnish cache server

谁能告诉我我错过了哪一步。
谢啦，谢啦