Quick docker PHP 8 setup for composer and unit testing

php8_docker.sh

# Terminal Tab #1 (with privileges inside container)
# =============
cd "/the/dir/you/want/to/work/with/php8"
docker run --name php8 \
      -it \
      -v $PWD:/var/php:rw \
      php:8.0-cli-alpine3.12 \
      ash

cd /tmp
php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php composer-setup.php  --quiet --install-dir="/usr/local/bin" --filename="composer" --2 
php -r "unlink('composer-setup.php');"
apk update
apk add git
mkdir /home/php

# Terminal Tab #2 (with the same UID:GID inside container)
# ======================
docker exec -it \
       -u $(id -u):$(id -g) \
       php8 \
       ash
HOME=/var/php
cd $HOME
# Then run composer install or any other command.
# Be prepared that composer can ask for a token to access git repo via ssh

# Clean when the work is done and the container is stopped
docker rm php8