Use docker to generate config file replacing env variables in template

Conf.class.php.template

<?php
class Conf {

  public static $SERVER_NAME;
  public static $SERVER_DB;
    
  public static function init_values() {
    self::$SERVER_NAME = "$NAME";
    self::$SERVER_DB = "$DB";
  }
}

Conf::init_values();
?>
        
        

docker_compose.yml

web:
  build: .
  ports:
    - "8000:80"
  environment:
    NAME: mysql
    DB: gbdbo

Dockerfile

FROM php:5.5-apache
COPY . /var/www/html/
RUN docker-php-ext-install mysqli
RUN sed -i '/DocumentRoot/c\DocumentRoot /var/www/html/htdocs' /etc/apache2/apache2.conf
RUN echo 'date.timezone = UTC' >> /usr/local/etc/php/conf.d/php.ini
RUN a2enmod rewrite
RUN apt-get update; apt-get install -y gettext
RUN chmod -R 700 ./generate_config_php
ENTRYPOINT [ "./generate_config_php" ]
CMD ["apache2-foreground"]

generate_config_php.sh

#!/bin/sh

export SERVER_NAME=\$SERVER_NAME
export SERVER_DB=\$SERVER_DB

envsubst  < Conf.class.php.template > Conf.class.php

exec "$@"