Example of docker compose file with WP and WP-CLI (allowed root). Note to self: when specifying command parameter in the compose file you'll need to add the default entrypoint and commands that are running on the default image you're pulling info from.

docker-composer.yaml

version: "3.9"

services:
  db:
    image: mysql:5.7
    volumes:
      - db_data:/var/lib/mysql
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: somewordpress
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: wordpress

  wordpress:
    depends_on:
      - db
    image: wordpress:latest
    ports:
      - "8000:80"
    restart: always
    volumes:
      - ./:/var/www/html
    environment:
      WORDPRESS_DB_HOST: db:3306
      WORDPRESS_DB_USER: wordpress
      WORDPRESS_DB_PASSWORD: wordpress
      WORDPRESS_DB_NAME: wordpress
      WP_CLI_ALLOW_ROOT: "true"
    command: >
      bash -c "curl -O https://raw.githubusercontent.com/wp-cli/builds/gh-pages/phar/wp-cli.phar;
      chmod +x wp-cli.phar;
      mv wp-cli.phar /usr/local/bin/wp;
      sh /usr/local/bin/docker-entrypoint.sh;
      apache2-foreground;"

volumes:
  db_data: {}