连接到 dockercompose mysql 容器会拒绝访问，但运行相同映像的 docker 不会

我在连接使用docker compose启动的mysql docker容器时遇到一些问题.这是一篇很长的帖子(抱歉！).

这是我的docker .yml文件:

db:
  image: mysql:5.7
  ports:
    - "3306:3306" # I have tried both ports and expose "3306". Still doesn't work 
  environment:
    - MYSQL_ROOT_PASSWORD="secret"
    - MYSQL_USER="django"
    - MYSQL_PASSWORD="secret"
    - MYSQL_DATABASE="myAppDB"

然后:

$> docker-compose build
db uses an image, skipping #expected!
$> docker-compose up
<<LOTS OF OUTPUT>>

好的，现在我有一个正在运行的docker容器运行程序mysql:5.7.太棒了还是这样？

$> docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
c7216f99ca0f        mysql:5.7           "docker-entrypoint.sh"   3 minutes ago       Up 3 minutes        0.0.0.0:3306->3306/tcp   sharpfin_db_1

$> docker-machine ip dev
192.168.99.100
$> mysql -h 192.168.99.100 -P 3306 -u django -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'django'@'192.168.99.1' (using password: YES)

好吧，也许这与连接到docker compose容器有关？

$> docker exec -it c7216f99ca0f /bin/bash
root@c7216f99ca0f:/#
root@c7216f99ca0f:/# mysql -u django -p                                                                                                                                                           
Enter password: 
ERROR 1045 (28000): Access denied for user 'django'@'localhost' (using password: YES)

好吧，docker mysql不让我连接，不知道为什么.让我们看看在没有docker compose的情况下try 这样做会发生什么:

$> docker run --name run-mysql -e MYSQL_ROOT_PASSWORD="secret" -e MYSQL_USER="django" -e MYSQL_PASSWORD="secret" -e MYSQL_DATABASE="myAppDB" -p "3306:3306" mysql:5.7
<<LOTS OF OUTPUT SAME AS BEFORE>>

好了，现在我们有了一个容器，它运行着和之前相同的图像，具有相同的设置.(我认为这个断言可能不是真的——docker compose对docker run做了一些不同的事情).

$> docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
73071b929e82        mysql:5.7           "docker-entrypoint.sh"   3 minutes ago       Up 3 minutes        0.0.0.0:3306->3306/tcp   run-mysql

这是我的容器(名为run mysql).让我们连线！

$> mysql -h 192.168.99.100 -P 3306 -u django -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.12 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| myAppDB            |
+--------------------+
2 rows in set (0.01 sec)

mysql>

好吧可以登录.真奇怪...那从容器里面呢？

$> docker exec -it 73071b929e82 /bin/bash
root@73071b929e82:/# mysql -u django -p                                                                                                                                                           
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.12 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| myAppDB            |
+--------------------+
2 rows in set (0.00 sec)

mysql> 

好的，当我用docker run启动时，我可以从容器内外登录，但不能用docker compose.发生什么事？docker compose肯定在幕后做了一些改变数据库初始化方式的事情.

如果我也try 使用root用户，以上所有内容都是完全相同的.所以这不是django用户的权限问题.

有没有办法解决这个问题？