如何从docker-compose.yml运行php文件

I'm working on a docker project and I want to run a php file which will configure the database for the project.

My Docker file :

FROM php:7.2-apache  
LABEL maintainer="admin@ksoftlabs.com"  
COPY site/ /var/www/html  
RUN chmod -R 777 /var/www/html  
RUN docker-php-ext-install mysqli  
COPY 000-default.conf /etc/apache2/sites-    available/000-default.conf  
EXPOSE 80  
CMD ["/usr/sbin/apache2ctl", "-D", "FOREGROUND"]  

My docker-compose.yml

version: '3.1'
services:
    db:
      image: mysql
      command: 
        --default-authentication-plugin=mysql_native_password
      restart: always
      environment:
        MYSQL_ROOT_PASSWORD: root
        MYSQL_DATABASE: group_db
    server:
        image : apache
        ports:
            - "80:80"

I want to run the install.php which will be in /var/www/html/ directory. How can I do that?

Edit : I want to run this file automatically after the container is up

Would running it earlier work?

After RUN docker-php-ext-install mysqli, put RUN php /path/to/your/file.php?