How to get access to php.ini file

I went with the uploads.ini route with a custom Docker image.

Dockerfile

FROM wordpress:latest

RUN touch /usr/local/etc/php/conf.d/uploads.ini \
    && echo "upload_max_filesize = 10M;" >> /usr/local/etc/php/conf.d/uploads.ini

You should change gforghetti to your Docker ID

docker image build -t gforghetti/wordpress:latest .

Then replace the wordpress image in the docker-compose.yml file with the custom image.

Bring up the stack and see if it works.