常連

### 前提・実現したいこと
Docker上で、APP：Django、DB：MySQLの環境を構築したいです。

###【問題】
DockerToolBox上のIPアドレス(192.168.99.100)で確認したときにDjangoのロケットを表示させたいのですが、
サイトにアクセスができない現状です。
http://192.168.99.100:8000/

docker-compose buildし、upをしたときに、WEBアプリの方で下記エラーが出ます。
```
web_1  | MySQLdb._exceptions.OperationalError: (2002, "Can't connect to MySQL server on 'db' (115)")
```

【現状】
下記サイトを参照した状態です。
https://qiita.com/cortyuming/items/e587fc045ee7424466b0
下記、Gitの状態です。

- core
-- __init__.py
-- asgi.py
-- settings.py
-- urls.py
-- wsgi.py
- Dockerfile
- docker-compose.yml
- manage.py
- requirements.txt
- wait-for-it.sh


```Dockerfile
FROM python:3
ENV PYTHONUNBUFFERED 1
RUN mkdir -p /var/www/webapp
WORKDIR /var/www/webapp
ADD requirements.txt /var/www/webapp/
RUN pip install -r requirements.txt
ADD . /var/www/webapp/
```

docakr-compose.yml
```
version: '3'
services:
  db:
     image: mysql:5.7
     command: mysqld --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci
     volumes:
     - .:/var/www/webapp
     restart: always
     environment:
       MYSQL_ROOT_PASSWORD: django
       MYSQL_DATABASE: django
       MYSQL_USER: django
       MYSQL_PASSWORD: django
  web:
     build: .
     command: sh -c "./wait-for-it.sh db:3306; python3 manage.py runserver 0.0.0.0:8000"
     volumes:
     - .:/var/www/webapp
     ports:
     - "8080:8000"
     depends_on:
     - db
```

requirements.txt
```
Django>=2.0.1
mysqlclient
```


### 試したこと
- localhost:8000などにアクセスを行うなどは行いました。
- PostgreSQLで環境を構築することは問題なく行えましたが、MySQLだとエラーが発生してしまう状態です。


### エラー（長すぎるため貼らないほうがいいかと思いますが、、）
```
db_1   | 2020-04-13 11:44:58+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 5.7.29-1debian10 started.
db_1   | 2020-04-13 11:44:58+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
db_1   | 2020-04-13 11:44:58+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 5.7.29-1debian10 started.
db_1   | 2020-04-13 11:44:59+00:00 [Note] [Entrypoint]: Initializing database files
db_1   | 2020-04-13T11:44:59.073461Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
db_1   | 2020-04-13T11:44:59.346916Z 0 [Warning] InnoDB: New log files created, LSN=45790
db_1   | 2020-04-13T11:44:59.390144Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
db_1   | 2020-04-13T11:44:59.447488Z 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: 34437735-7d7c-11ea-a4a4-0242ac170002.
db_1   | 2020-04-13T11:44:59.448534Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
db_1   | 2020-04-13T11:45:00.441638Z 0 [Warning] CA certificate ca.pem is self signed.
web_1  | /usr/bin/env: ‘bash\r’: No such file or directory
web_1  | Watching for file changes with StatReloader
web_1  | Performing system checks...
web_1  |
web_1  | Exception in thread django-main-thread:
web_1  | Traceback (most recent call last):
＜中略＞
web_1  |     return Database.connect(**conn_params)
web_1  |   File "/usr/local/lib/python3.8/site-packages/MySQLdb/__init__.py", line 84, in Connect
web_1  |     return Connection(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.8/site-packages/MySQLdb/connections.py", line 179, in __init__
web_1  |     super(Connection, self).__init__(*args, **kwargs2)
web_1  | MySQLdb._exceptions.OperationalError: (2002, "Can't connect to MySQL server on 'db' (115)")
web_1  |
web_1  | The above exception was the direct cause of the following exception:
web_1  |
web_1  | Traceback (most recent call last):
＜中略＞
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/core/checks/registry.py", line 72, in run_checks
web_1  |     new_errors = check(app_configs=app_configs)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/core/checks/model_checks.py", line 34, in check_all_models
web_1  |     errors.extend(model.check(**kwargs))
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/models/base.py", line 1275, in check
web_1  |     *cls._check_constraints(),
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/models/base.py", line 1841, in _check_constraints
web_1  |     connection.features.supports_table_check_constraints or
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/utils/functional.py", line 48, in __get__
web_1  |     res = instance.__dict__[self.name] = self.func(instance)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/mysql/features.py", line 93, in supports_column_check_constraints
web_1  |     if self.connection.mysql_is_mariadb:
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/utils/functional.py", line 48, in __get__
web_1  |     res = instance.__dict__[self.name] = self.func(instance)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/mysql/base.py", line 363, in mysql_is_mariadb
web_1  |     return 'mariadb' in self.mysql_server_info.lower()
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/utils/functional.py", line 48, in __get__
web_1  |     res = instance.__dict__[self.name] = self.func(instance)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/mysql/base.py", line 350, in mysql_server_info
web_1  |     with self.temporary_connection() as cursor:
web_1  |   File "/usr/local/lib/python3.8/contextlib.py", line 113, in __enter__
web_1  |     return next(self.gen)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/base/base.py", line 604, in temporary_connection
web_1  |     with self.cursor() as cursor:
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/base/base.py", line 260, in cursor
web_1  |     return self._cursor()
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/base/base.py", line 236, in _cursor
web_1  |     self.ensure_connection()
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/base/base.py", line 220, in ensure_connection
web_1  |     self.connect()
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/utils.py", line 90, in __exit__
web_1  |     raise dj_exc_value.with_traceback(traceback) from exc_value
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/base/base.py", line 220, in ensure_connection
web_1  |     self.connect()
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/base/base.py", line 197, in connect
web_1  |     self.connection = self.get_new_connection(conn_params)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.8/site-packages/django/db/backends/mysql/base.py", line 233, in get_new_connection
web_1  |     return Database.connect(**conn_params)
web_1  |   File "/usr/local/lib/python3.8/site-packages/MySQLdb/__init__.py", line 84, in Connect
web_1  |     return Connection(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.8/site-packages/MySQLdb/connections.py", line 179, in __init__
web_1  |     super(Connection, self).__init__(*args, **kwargs2)
db_1   | 2020-04-13T11:45:00.666232Z 1 [Warning] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option.
db_1   | 2020-04-13 11:45:02+00:00 [Note] [Entrypoint]: Database files initialized
db_1   | 2020-04-13 11:45:02+00:00 [Note] [Entrypoint]: Starting temporary server
db_1   | 2020-04-13 11:45:02+00:00 [Note] [Entrypoint]: Waiting for server startup
db_1   | 2020-04-13T11:45:03.111103Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
db_1   | 2020-04-13T11:45:03.115156Z 0 [Note] mysqld (mysqld 5.7.29) starting as process 75 ...
＜中略＞
db_1   | 2020-04-13T11:45:07.887911Z 0 [Note] Found ca.pem, server-cert.pem and server-key.pem in data directory. Trying to enable SSL support using them.
db_1   | 2020-04-13T11:45:07.888181Z 0 [Note] Skipping generation of SSL certificates as certificate files are present in data directory.
db_1   | 2020-04-13T11:45:07.889414Z 0 [Warning] CA certificate ca.pem is self signed.
db_1   | 2020-04-13T11:45:07.889696Z 0 [Note] Skipping generation of RSA key pair as key files are present in data directory.
db_1   | 2020-04-13T11:45:07.890716Z 0 [Note] Server hostname (bind-address): '*'; port: 3306
db_1   | 2020-04-13T11:45:07.890897Z 0 [Note] IPv6 is available.
db_1   | 2020-04-13T11:45:07.891022Z 0 [Note]   - '::' resolves to '::';
db_1   | 2020-04-13T11:45:07.891253Z 0 [Note] Server socket created on IP: '::'.
db_1   | 2020-04-13T11:45:07.892482Z 0 [Warning] Insecure configuration for --pid-file: Location '/var/run/mysqld' in the path is accessible to all OS users. Consider choosing a different directory.
db_1   | 2020-04-13T11:45:07.901810Z 0 [Note] Event Scheduler: Loaded 0 events
```

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