How to Keep wp-content folder after releasing a new container?

Question

I have a Wordpress instance on Azure App Service. I release it as an Azure Docker Container. I use a single DockerFile. My release process is working as expected but it's updating my wp-content folder after each release. I'm missing my new media files.

How can I secure them? Or can I download all media items via any plugins etc?

DockerFile

FROM wordpress:5.9.2-php7.3-apache

COPY html /var/www/html

# ssh
ENV SSH_PASSWD "root:Docker!"
RUN apt-get update \
        && apt-get install -y --no-install-recommends dialog \
        && apt-get update \
 && apt-get install -y --no-install-recommends openssh-server \
 && echo "$SSH_PASSWD" | chpasswd 

COPY sshd_config /etc/ssh/
COPY init.sh /usr/local/bin/

RUN chmod u+x /usr/local/bin/init.sh
EXPOSE 8000 2222

ENTRYPOINT ["init.sh"]

init.sh

#!/bin/bash
set -e

echo "Starting SSH ..."
service ssh start

chown -R www-data:www-data /var/www/html/
chown -R www-data:www-data /var/www/html/wp-content/
chmod -R 775 /var/www/html/
chmod -R 775 /var/www/html/wp-content/

apache2-foreground

Thanks.