wordpress works now with :

+ volumes in mariadb container
+ db pswd in quotes
+ somes other settings

srcs/requirements/mariadb/conf/create_db.sql

@@ -1,5 +1,5 @@
 USE mysql;
 
 CREATE DATABASE IF NOT EXISTS ${DB_NAME};
-CREATE USER IF NOT EXISTS '${DB_USER}'@'localhost' IDENTIFIED BY '${DB_PSWD}';
-GRANT ALL PRIVILEGES ON ${DB_NAME}.* TO '${DB_USER}'@'localhost' with grant option;
+CREATE USER IF NOT EXISTS '${DB_USER}'@'%' IDENTIFIED BY '${DB_PSWD}';
+GRANT ALL PRIVILEGES ON ${DB_NAME}.* TO '${DB_USER}'@'%' with grant option;