我有下一个dockerfile：

FROM ubuntu:16.04
RUN apt-get update && apt-get upgrade -y && apt-get install -y apache2 MysqL-server MysqL-client

之后,Docker构建问我密码root：

While not mandatory,it is highly recommended that you set a password for the
MysqL administrative "root" user.

If this field is left blank,the password will not be changed.

New password for the MysqL "root" user:

我输入密码,但是,它只是保持该状态.

我可以这样安装MysqL吗？我不想自动安装它