docker-compose not passing env variables to PHP - php

Question

I have the following set up and have tried all the ways that I can find to pass env variables to PHP but none of the them are working. Not sure what I have set up wrong. Ideally I want to be able to get the variable using $_SERVER['MY_ENV'], but I have also tried getenv('MY_ENV') with no success.
docker-compose.yml
version: '3.9'
services:
app:
restart: unless-stopped
build:
context: ./
dockerfile: Dockerfile
environment:
- MY_ENV=dev
command: php -S app:8000 -t public
ports:
- "8888:8000"
depends_on:
- db
volumes:
- ./:/var/www
links:
- db
networks:
- myapp
db:
image: mysql:5.7
restart: always
command: mysqld --sql_mode="" --default-authentication plugin=mysql_native_password
environment:
MYSQL_ROOT_PASSWORD: root
MYSQL_DATABASE: laravel
MYSQL_USER: laravel
MYSQL_PASSWORD: secret
ports:
- "3306:3306"
volumes:
- ./mysql-data:/var/lib/mysql
networks:
- myapp
networks:
myapp:
DockerFile
FROM php:7.2-fpm
RUN apt-get update -y && apt-get install -y openssl zip unzip git cron
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
RUN apt-get clean && rm -rf /var/lib/apt/lists/*
RUN docker-php-ext-install pdo pdo_mysql
COPY composer.lock composer.json /var/www/
WORKDIR /var/www
RUN groupadd -g 1000 www
RUN useradd -u 1000 -ms /bin/bash -g www www
COPY --chown=www:www . /var/www
USER www
EXPOSE 9000
CMD ["php-fpm"]