fix: read vars from existing config file

setup

@@ -55,6 +55,16 @@ if [ $CONFIG_EXISTS == "false" ] || [ $USE_EXISTING_CONFIG == "n" ]; then
     echo "MARIADB_HOST_IP_ADDRESS="$MARIADB_HOST_IP_ADDRESS >> config
     echo "MARIADB_HOST_PORT="$MARIADB_HOST_PORT >> config
     echo "MARIADB_ROOT_PASSWORD="$MARIADB_ROOT_PASSWORD >> config
+
+    echo "Config file 'config' created!"
+else
+    echo "Use existing config file 'config'!"
+
+    while read line; do
+        if [[ $line == *"MARIADB_ROOT_PASSWORD="* ]]; then
+            MARIADB_ROOT_PASSWORD=$(echo $line | cut -c 23-)
+        fi
+    done < "config"
 fi
 
 cat "config" >> ".env"