# Backup
docker exec CONTAINER /usr/bin/mysqldump -u root --password=root DATABASE > backup.sql

# or
docker exec CONTAINER sh -c 'exec mysqldump --all-databases -uroot -p\$MYSQL_ROOT_PASSWORD' > alldatabase.sql

# Restore
cat backup.sql | docker exec -i CONTAINER /usr/bin/mysql -u root --password=root DATABASE

# or
cat alldatabase.sql | docker exec -i CONTAINER sh -c 'exec mysql -uroot -p$MYSQL_ROOT_PASSWORD'