Deploy a Dockerized Laravel app using Apache on Heroku - laravel

Question

I'm trying to deploy a Laravel 5.5 app using Docker on Heroku. I'm coming up against the problem where Heroku dynamically assigns the $PORT value though, and I can't figure out where to tell Apache to use $PORT instead of port 80. Has anyone else had success deploying an app using Apache in Docker to Heroku with the $PORT specification?
To be specific, this is the error I get tailing the Heroku logs:
2019-01-31T14:01:17.605297+00:00 app[web.1]: (13)Permission denied: AH00072: make_sock: could not bind to address 0.0.0.0:80
which I understand to mean that the container is trying to listen on Port 80, but the host is using $PORT instead of 80.
Here's my Dockerfile:
FROM php:7.1.5-apache
#install all the system dependencies and enable PHP modules
RUN apt-get update && apt-get install -y \
libicu-dev \
libpq-dev \
libmcrypt-dev \
git \
zip \
unzip \
&& rm -r /var/lib/apt/lists/* \
&& docker-php-ext-configure pdo_mysql --with-pdo-mysql=mysqlnd \
&& docker-php-ext-install \
intl \
mbstring \
mcrypt \
pcntl \
pdo_mysql \
pdo_pgsql \
pgsql \
zip \
opcache
ENV PHPREDIS_VERSION 3.0.0
RUN mkdir -p /usr/src/php/ext/redis \
&& curl -L https://github.com/phpredis/phpredis/archive/$PHPREDIS_VERSION.tar.gz | tar xvz -C /usr/src/php/ext/redis --strip 1 \
&& echo 'redis' >> /usr/src/php-available-exts \
&& docker-php-ext-install redis
#install composer
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/bin/ --filename=composer
#set our application folder as an environment variable
ENV APP_HOME /var/www/html
#change uid and gid of apache to docker user uid/gid
RUN usermod -u 1000 www-data && groupmod -g 1000 www-data
#change the web_root to laravel /var/www/html/public folder
RUN sed -i -e "s/html/html\/public/g" /etc/apache2/sites-enabled/000-default.conf
# enable apache module rewrite
RUN a2enmod rewrite
#copy source files and run composer
COPY . $APP_HOME
# install all PHP dependencies
RUN composer install --no-interaction
#change ownership of our applications
RUN chown -R www-data:www-data $APP_HOME
And here's my Heroku Procfile:
web: vendor/bin/heroku-php-apache2 public/
And here's my heroku.yml:
build:
docker:
web: Dockerfile
Thanks!

Answer 1

Got it.
Using this SO post, I discovered I could insert a CMD statement at the end of my Dockerfile to sed replace the ports in my apache config files to the magical $PORT environment variable at run time.
New Dockerfile below:
#start with our base image (the foundation) - version 7.1.5
FROM php:7.1.5-apache
#install all the system dependencies and enable PHP modules
RUN apt-get update && apt-get install -y \
libicu-dev \
libpq-dev \
libmcrypt-dev \
git \
zip \
unzip \
&& rm -r /var/lib/apt/lists/* \
&& docker-php-ext-configure pdo_mysql --with-pdo-mysql=mysqlnd \
&& docker-php-ext-install \
intl \
mbstring \
mcrypt \
pcntl \
pdo_mysql \
pdo_pgsql \
pgsql \
zip \
opcache
ENV PHPREDIS_VERSION 3.0.0
RUN mkdir -p /usr/src/php/ext/redis \
&& curl -L https://github.com/phpredis/phpredis/archive/$PHPREDIS_VERSION.tar.gz | tar xvz -C /usr/src/php/ext/redis --strip 1 \
&& echo 'redis' >> /usr/src/php-available-exts \
&& docker-php-ext-install redis
#install composer
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/bin/ --filename=composer
#set our application folder as an environment variable
ENV APP_HOME /var/www/html
#change uid and gid of apache to docker user uid/gid
RUN usermod -u 1000 www-data && groupmod -g 1000 www-data
#change the web_root to laravel /var/www/html/public folder
RUN sed -i -e "s/html/html\/public/g" /etc/apache2/sites-enabled/000-default.conf
# enable apache module rewrite
RUN a2enmod rewrite
#copy source files and run composer
COPY . $APP_HOME
# install all PHP dependencies
RUN composer install --no-interaction
#change ownership of our applications
RUN chown -R www-data:www-data $APP_HOME
#update apache port at runtime for Heroku
ENTRYPOINT []
CMD sed -i "s/80/$PORT/g" /etc/apache2/sites-enabled/000-default.conf /etc/apache2/ports.conf && docker-php-entrypoint apache2-foreground