python - Docker Compose Up 时数据库服务连接错误

Question

现在我正在使用 docker 将我的 Python django 应用程序容器化。我在 docker-compose 文件中有两个服务：web和db. Web 服务依赖于 db 服务。虽然我跑得docker-compose build很好，但是当我跑docker-compose up的时候，web服务总是报错：

web_1  | Performing system checks...
web_1  |
web_1  | System check identified no issues (0 silenced).
web_1  | Exception in thread django-main-thread:
web_1  | Traceback (most recent call last):
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/base.py", line 219, in ensure_connection
web_1  |     self.connect()
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/base.py", line 200, in connect
web_1  |     self.connection = self.get_new_connection(conn_params)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/postgresql/base.py", line 187, in get_new_connection
web_1  |     connection = Database.connect(**conn_params)
web_1  |   File "/usr/local/lib/python3.9/site-packages/psycopg2/__init__.py", line 127, in connect
web_1  |     conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
web_1  | psycopg2.OperationalError: could not connect to server: Connection refused
web_1  |    Is the server running on host "localhost" (127.0.0.1) and accepting
web_1  |    TCP/IP connections on port 5432?
web_1  | could not connect to server: Cannot assign requested address
web_1  |    Is the server running on host "localhost" (::1) and accepting
web_1  |    TCP/IP connections on port 5432?
web_1  |
web_1  |
web_1  | The above exception was the direct cause of the following exception:
web_1  |
web_1  | Traceback (most recent call last):
web_1  |   File "/usr/local/lib/python3.9/threading.py", line 950, in _bootstrap_inner
web_1  |     self.run()
web_1  |   File "/usr/local/lib/python3.9/threading.py", line 888, in run
web_1  |     self._target(*self._args, **self._kwargs)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/utils/autoreload.py", line 53, in wrapper
web_1  |     fn(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/core/management/commands/runserver.py", line 121, in inner_run
web_1  |     self.check_migrations()
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/core/management/base.py", line 459, in check_migrations
web_1  |     executor = MigrationExecutor(connections[DEFAULT_DB_ALIAS])
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/migrations/executor.py", line 18, in __init__
web_1  |     self.loader = MigrationLoader(self.connection)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/migrations/loader.py", line 53, in __init__
web_1  |     self.build_graph()
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/migrations/loader.py", line 216, in build_graph
web_1  |     self.applied_migrations = recorder.applied_migrations()
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/migrations/recorder.py", line 77, in applied_migrations
web_1  |     if self.has_table():
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/migrations/recorder.py", line 55, in has_table
web_1  |     with self.connection.cursor() as cursor:
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/base.py", line 259, in cursor
web_1  |     return self._cursor()
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/base.py", line 235, in _cursor
web_1  |     self.ensure_connection()
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/base.py", line 219, in ensure_connection
web_1  |     self.connect()
web_1  |   File "/usr/local/lib/python3.9/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/python3.9/site-packages/django/db/backends/base/base.py", line 219, in ensure_connection
web_1  |     self.connect()
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/base/base.py", line 200, in connect
web_1  |     self.connection = self.get_new_connection(conn_params)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/utils/asyncio.py", line 26, in inner
web_1  |     return func(*args, **kwargs)
web_1  |   File "/usr/local/lib/python3.9/site-packages/django/db/backends/postgresql/base.py", line 187, in get_new_connection
web_1  |     connection = Database.connect(**conn_params)
web_1  |   File "/usr/local/lib/python3.9/site-packages/psycopg2/__init__.py", line 127, in connect
web_1  |     conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
web_1  | django.db.utils.OperationalError: could not connect to server: Connection refused
web_1  |    Is the server running on host "localhost" (127.0.0.1) and accepting
web_1  |    TCP/IP connections on port 5432?
web_1  | could not connect to server: Cannot assign requested address
web_1  |    Is the server running on host "localhost" (::1) and accepting
web_1  |    TCP/IP connections on port 5432?

另一件事是：我注意到很多人也通过以下方式添加environment到web服务中：

 - DB_HOST=db
      - DB_NAME=app
      - DB_USER=postgres
      - DB_PASS=axasxaxa

这些DB_HOST, DB_USER等来自哪里？我们可以将其命名为DB_HOSTbut notDB_HOST_test或其他名称吗？

最后这是我的docker-compose file：

#python manage.py wait_for_db &&
version: "3.7"
services:
  db:
    image: postgres:10-alpine
    environment:
      - POSTGRES_DB=realestate
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=xsxs
      - POSTGRES_HOST_AUTH_METHOD=trust
    ports:
      - "5432:5432"

  web:
    build: .
    command: >
      sh -c 'python manage.py wait_for_db &&
             python manage.py runserver 0.0.0.0:8000'
    volumes:
      - .:/usr/src/code/
    ports:
      - "8000:8000"
    env_file:
      - ./.env
    environment:
      - DB_HOST=db
      - DB_NAME=app
      - DB_USER=postgres
      - DB_PASS=xsxs
    depends_on:
      - db

标签： pythondjangodocker