Can't connect wordpress to mariadb (docker) - wordpress

Question

I have two containers, one for mariadb and the other for wordpress.
I'm using this configuration for mariadb:
version: "3"
services:
mariadb:
image: mariadb
container_name: mariadb
environment:
MYSQL_ROOT_PASSWORD: "${MYSQL_ROOT_PASSWORD}"
volumes:
- ./data:/var/lib/mysql
ports:
- "127.0.0.1:3306:3306"
restart: unless-stopped
networks:
- web
networks:
web:
external: true
And this for wordpress
version: '3'
services:
# Wordpress
myWordpress:
image: wordpress:php8.1
container_name: myWordpress
hostname: myWordpress
restart: unless-stopped
volumes: [ './data:/var/www/html' ]
environment:
- WORDPRESS_DB_HOST=mariadb
- WORDPRESS_DB_USER="${WORDPRESS_DB_USER}"
- WORDPRESS_DB_PASSWORD="${WORDPRESS_DB_PASSWORD}"
- WORDPRESS_DB_NAME="${WORDPRESS_DB_NAME}"
networks:
- web
networks:
web:
external: true
I already created the network web and logged in mysql root , created the database & user and executed this command: GRANT ALL PRIVILEGES ON wp_db.* TO 'wp_user'#'%';.
Then I logged in mysql using that user and its password.
docker exec -it mariadb bash
mysql -u wp_user -pMyPassword
# Welcome to the MariaDB monitor. Commands end with ; or \g.
# ...
The issue appears when I visit wordpress, I see this message:
Warning: mysqli_real_connect(): (HY000/1045): Access denied for user '"wp_user"'#'172.16.32.5' (using password: YES) in /var/www/html/wp-includes/wp-db.php on line 1753
Access denied for user '"wp_user"'#'172.16.32.5' (using password: YES)
I feel that the problem is in WORDPRESS_DB_HOST variable, I pointed it to mariadb container name, I also tried pointing it to localhost since both containers share the same network web, but his didn't work either, and the same exact error message appeared.

Answer 1

One month later, I went back to this issue and tried putting environment variables in quotes, it worked as expected.
So instead of:
- WORDPRESS_DB_USER="${WORDPRESS_DB_USER}"
It should be
- "WORDPRESS_DB_USER=${WORDPRESS_DB_USER}"