Django、MySQLの開発環境をDockerで構築する

Question

下記のQiitaを参考にして、Django、MySQLの開発環境をDockerで構築しています。

https://qiita.com/kenkono/items/6221ad12670d1ae8b1dd

マイグレーションをするところで、下記エラーが発生してしまいます。

docker-compose run python ./manage.py makemigrations

$ docker-compose run python ./manage.py makemigrations
Starting djangotest2_db_1 ... 
Starting djangotest2_db_1 ... done
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/pymysql/connections.py", line 920, in connect
    **kwargs)
  File "/usr/local/lib/python3.6/socket.py", line 704, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
  File "/usr/local/lib/python3.6/socket.py", line 745, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -3] Temporary failure in name resolution

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 216, in ensure_connection
    self.connect()
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 194, in connect
    self.connection = self.get_new_connection(conn_params)
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 236, in get_new_connection
    return Database.connect(**conn_params)
  File "/usr/local/lib/python3.6/site-packages/pymysql/__init__.py", line 90, in Connect
    return Connection(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/pymysql/connections.py", line 699, in __init__
    self.connect()
  File "/usr/local/lib/python3.6/site-packages/pymysql/connections.py", line 967, in connect
    raise exc
pymysql.err.OperationalError: (2003, "Can't connect to MySQL server on 'db' ([Errno -3] Temporary failure in name resolution)")

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "./manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 365, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python3.6/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python3.6/site-packages/django/core/management/base.py", line 332, in execute
    self.check()
  File "/usr/local/lib/python3.6/site-packages/django/core/management/base.py", line 364, in check
    include_deployment_checks=include_deployment_checks,
  File "/usr/local/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 57, in _run_checks
    issues = run_checks(tags=[Tags.database])
  File "/usr/local/lib/python3.6/site-packages/django/core/checks/registry.py", line 73, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/usr/local/lib/python3.6/site-packages/django/core/checks/database.py", line 10, in check_database_backends
    issues.extend(conn.validation.check(**kwargs))
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/validation.py", line 9, in check
    issues.extend(self._check_sql_mode(**kwargs))
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/validation.py", line 13, in _check_sql_mode
    with self.connection.cursor() as cursor:
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 255, in cursor
    return self._cursor()
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 232, in _cursor
    self.ensure_connection()
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 216, in ensure_connection
    self.connect()
  File "/usr/local/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 216, in ensure_connection
    self.connect()
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/base/base.py", line 194, in connect
    self.connection = self.get_new_connection(conn_params)
  File "/usr/local/lib/python3.6/site-packages/django/db/backends/mysql/base.py", line 236, in get_new_connection
    return Database.connect(**conn_params)
  File "/usr/local/lib/python3.6/site-packages/pymysql/__init__.py", line 90, in Connect
    return Connection(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/pymysql/connections.py", line 699, in __init__
    self.connect()
  File "/usr/local/lib/python3.6/site-packages/pymysql/connections.py", line 967, in connect
    raise exc
django.db.utils.OperationalError: (2003, "Can't connect to MySQL server on 'db' ([Errno -3] Temporary failure in name resolution)")

バージョンが関係しているのか、設定が足りていないのか不明です。

よろしくお願いします。

■環境

Windows - WSL Ubuntu 18.04

Macでも試したところ同じ現象でした。

Comments

[netsuy]

docker execでdb側のコンテナには入れますか？
また、djangoのコンテナに入り、python ./manage.py dbshellするとどうなりますか？

[haruyasu]

コメントありがとうございます。

docker-compose up db
dbを起動した後に、別ターミナルで、
docker-compose run python ./manage.py migrations
をしたら、無事にマイグレートができました。

docker-compose runだけでは、dbが起動していなかったから、MySQLに接続できないエラーがでていたのですね。

記事には、docker-compose up dbをすると書いてなかったので、混乱していました。

[netsuy]

よかったです！

Answer 1

まずはデータベースを動作させる。

docker-compose up db

別ターミナルを開いて、djangoを動作させる。

docker-compose run python ./manage.py migrations

これで無事マイグレーションができます。