docker-compose django-postgres錯誤

Question

我完全按照本教程（ http://docs.docker.com/compose/django/ ）進行操作，但是在進行docker-compose up此錯誤：

$ docker-compose up
Recreating composeexample_db_1...
Recreating composeexample_web_1...
Attaching to composeexample_db_1, composeexample_web_1
db_1  | LOG:  database system was shut down at 2015-07-27 16:17:21 UTC
db_1  | LOG:  MultiXact member wraparound protections are now enabled
db_1  | LOG:  database system is ready to accept connections
db_1  | LOG:  autovacuum launcher started
web_1 | Performing system checks...
web_1 | 
web_1 | System check identified no issues (0 silenced).
web_1 | Unhandled exception in thread started by <function wrapper at 0x7f43f0126ed8>
web_1 | Traceback (most recent call last):
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/utils/autoreload.py", line 225, in wrapper
web_1 |     fn(*args, **kwargs)
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line 112, in inner_run
web_1 |     self.check_migrations()
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line 164, in check_migrations
web_1 |     executor = MigrationExecutor(connections[DEFAULT_DB_ALIAS])
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 19, in __init__
web_1 |     self.loader = MigrationLoader(self.connection)
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/migrations/loader.py", line 47, in __init__
web_1 |     self.build_graph()
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/migrations/loader.py", line 182, in build_graph
web_1 |     self.applied_migrations = recorder.applied_migrations()
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/migrations/recorder.py", line 59, in applied_migrations
web_1 |     self.ensure_schema()
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/migrations/recorder.py", line 49, in ensure_schema
web_1 |     if self.Migration._meta.db_table in self.connection.introspection.table_names(self.connection.cursor()):
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/backends/base/base.py", line 162, in cursor
web_1 |     cursor = self.make_debug_cursor(self._cursor())
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/backends/base/base.py", line 135, in _cursor
web_1 |     self.ensure_connection()
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/backends/base/base.py", line 130, in ensure_connection
web_1 |     self.connect()
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/utils.py", line 97, in __exit__
web_1 |     six.reraise(dj_exc_type, dj_exc_value, traceback)
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/backends/base/base.py", line 130, in ensure_connection
web_1 |     self.connect()
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/backends/base/base.py", line 119, in connect
web_1 |     self.connection = self.get_new_connection(conn_params)
web_1 |   File "/usr/local/lib/python2.7/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 176, in get_new_connection
web_1 |     connection = Database.connect(**conn_params)
web_1 |   File "/usr/local/lib/python2.7/site-packages/psycopg2/__init__.py", line 164, in connect
web_1 |     conn = _connect(dsn, connection_factory=connection_factory, async=async)
web_1 | django.db.utils.OperationalError: could not connect to server: No route to host
web_1 |     Is the server running on host "db" (172.17.0.19) and accepting
web_1 |     TCP/IP connections on port 5432?

現在，這僅在我的Fedora 21系統上發生（內核= 4.0.4-202.fc21.x86_64），但是當我在Virtualbox中啟動Ubuntu實例時，它工作正常。

有指針嗎？

Answer 1

如果您再次運行相同的命令，那么我會遇到相同的問題和FWIW，它會起作用。 好像“ docker-compose up”同時啟動兩個容器，而django app容器嘗試在仍設置postgres容器時運行嗎？ 真是令人困惑。 ：*（

更新：

似乎我的猜想是對的，請訪問https://github.com/docker/compose/issues/374進行閱讀。

對於這種競爭情況，有些粗略但簡單的解決方法是讓django應用程序容器在運行命令之前先睡眠幾秒鍾，以便這些容器所依賴的服務（例如PostgreSQL）可以接受連接。 例如：yml文件中django服務下的docker-compose command: bash -c "sleep 3 && python manage.py runserver 0.0.0.0:8000" 。

另一種選擇是使用gunicorn或uwsgi運行django服務，在收到請求之前，該服務似乎不會實例化django應用程序。

希望這可以幫助當前與docker作戰的其他人