我完全按照本教程（http://docs.docker.com/compose/django/）进行操作，但是在执行此操作时docker-compose up出现此错误：
$ 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?
现在，这只发生在我的 Fedora 21 系统（内核=4.0.4-202.fc21.x86_64）上，但是当我在 Virtualbox 中启动一个 Ubuntu 实例时，它工作得很好。
任何指针？