docker，无法启动从正式docker映像mysql构建的docker mysql容器

我正在尝试从此docker compose文件启动db容器：

                    db:
                      image: mysql
                      environment:
                        MYSQL_ROOT_PASSWORD: root
                      volumes:
                        - "./testsql:/var/lib/mysql"
                    phpmyadmin:
                      image: phpmyadmin/phpmyadmin
                      container_name: phpmyadmin
                      volumes:
                        - /sessions
                      environment:
                       - PMA_ARBITRARY=1
                      restart: always
                      ports:
                       - "8082:80"
                      depends_on:
                        - db

我在容器日志中发现以下错误：

 2018-04-20T21:36:42.409677Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
            2018-04-20T21:36:42.420057Z 0 [ERROR] --initialize specified but the data directory has files in it. Aborting.
            2018-04-20T21:36:42.420341Z 0 [ERROR] Aborting
            2018-04-20T21:36:42.420428809Z

---

谢谢

testsql中有子目录吗

如果存在子目录，错误将如下所示再现

$ mkdir -p testsql/aaa
$ docker run -e MYSQL_ROOT_PASSWORD=r00t -v `pwd`/testsql:/var/lib/mysql mysql
Initializing database
2018-04-20T23:59:23.465762Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2018-04-20T23:59:23.468193Z 0 [ERROR] --initialize specified but the data directory has files in it. Aborting.
2018-04-20T23:59:23.468245Z 0 [ERROR] Aborting

$ 

如果没有子目录，则不会发出错误

$ rm -rf testsql/
$ mkdir testsql
$ docker run -e MYSQL_ROOT_PASSWORD=r00t -v `pwd`/testsql:/var/lib/mysql mysql
Initializing database
2018-04-21T00:04:06.012172Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2018-04-21T00:04:06.533290Z 0 [Warning] InnoDB: New log files created, LSN=45790
2018-04-21T00:04:06.629547Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2018-04-21T00:04:06.692854Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 823515e3-44f7-11e8-b4cf-0242ac110003.
...