How to modify the root password of mysql in docker

docker exec -it container ID /bin/bash

mysql -uroot -p

SET PASSWORD FOR 'root' = PASSWORD('set password');

docker restart container id

docker run -p 3308:3308 --name=mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.6
Initializing database

[root@localhost mugutu]# docker run -p 3308:3308 --name=mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.6
Initializing database
2018-12-02 13:42:53 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2018-12-02 13:42:53 0 [Note] Ignoring --secure-file-priv value as server is running with --bootstrap.
2018-12-02 13:42:53 0 [Note] /usr/sbin/mysqld (mysqld 5.6.41) started as process 32 ...