Dockerfile启动PHP容器，mysqli和a2enmod重写不起作用

I'm trying to start a container based on a dockerfile. it shoud have mysqli and a2enmod.

My Dockerfile is

FROM php:7.1-apache
RUN docker-php-ext-install mysqli && a2enmod rewrite && service apache2 restart

but the a2enmod is not enablad before start. When I Attach to the container bash I got that a2enmod was not enabled

$ a2enmod rewrite
Enabling module rewrite.
To activate the new configuration, you need to run: service apache2 restart
$ a2enmod rewrite
Module rewrite already enabled

What am I doing wrong?

As suggested by Alex Karshin, there was 2 problems.

1. I need to rebuild the docker image.
2. I don't need to restart the apache service because apache was not running during container initialization.

Fixing those issues solved my problem.