无法连接到 Docker 容器中的 PostgreSQL 数据库

Question

我使用 Python 3.7、Flask 和 Z399BD1EE587245ECAC6F39BEFAA9 创建了 web 应用程序。 为了部署它，我构建了 Docker 容器并尝试运行它，但出现以下错误：

D:\PyCharms\Module 6\app>docker run --env DB_URL=postgresql+psycopg2://test_user:password@127.0.0.1:5432/test_db -p 8000:8000 doc
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2336, in _wrap_pool_connect
    return fn()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 364, in connect
    return _ConnectionFairy._checkout(self)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 778, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 495, in checkout
    rec = pool._do_get()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/impl.py", line 140, in _do_get
    self._dec_overflow()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/langhelpers.py", line 70, in __exit__
    with_traceback=exc_tb,
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/impl.py", line 137, in _do_get
    return self._create_connection()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 309, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 440, in __init__
    self.__connect(first_connect_check=True)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 661, in __connect
    pool.logger.debug("Error on connect(): %s", e)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/langhelpers.py", line 70, in __exit__
    with_traceback=exc_tb,
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 656, in __connect
    connection = pool._invoke_creator(self)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/strategies.py", line 114, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/default.py", line 493, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/usr/local/lib/python3.7/site-packages/psycopg2/__init__.py", line 127, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError: could not connect to server: Connection refused
        Is the server running on host "127.0.0.1" and accepting
        TCP/IP connections on port 5432?
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
  File "./run.py", line 3, in <module>
    app = create_app()
  File "/app/core/__init__.py", line 21, in create_app
    db.create_all()
  File "/usr/local/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 1039, in create_all
    self._execute_for_all_tables(app, bind, 'create_all')
  File "/usr/local/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 1031, in _execute_for_all_tables
    op(bind=self.get_engine(app, bind), **extra)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/sql/schema.py", line 4554, in create_all
    ddl.SchemaGenerator, self, checkfirst=checkfirst, tables=tables
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2094, in _run_visitor
    with self._optional_conn_ctx_manager(connection) as conn:
  File "/usr/local/lib/python3.7/contextlib.py", line 112, in __enter__
    return next(self.gen)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2086, in _optional_conn_ctx_manager
    with self._contextual_connect() as conn:
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2302, in _contextual_connect
    self._wrap_pool_connect(self.pool.connect, None),
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2340, in _wrap_pool_connect
    e, dialect, self
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 1584, in _handle_dbapi_exception_noconnection
    sqlalchemy_exception, with_traceback=exc_info[2], from_=e
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2336, in _wrap_pool_connect
    return fn()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 364, in connect
    return _ConnectionFairy._checkout(self)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 778, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 495, in checkout
    rec = pool._do_get()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/impl.py", line 140, in _do_get
    self._dec_overflow()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/langhelpers.py", line 70, in __exit__
    with_traceback=exc_tb,
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/impl.py", line 137, in _do_get
    return self._create_connection()
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 309, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 440, in __init__
    self.__connect(first_connect_check=True)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 661, in __connect
    pool.logger.debug("Error on connect(): %s", e)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/langhelpers.py", line 70, in __exit__
    with_traceback=exc_tb,
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool/base.py", line 656, in __connect
    connection = pool._invoke_creator(self)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/strategies.py", line 114, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/default.py", line 493, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/usr/local/lib/python3.7/site-packages/psycopg2/__init__.py", line 127, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) could not connect to server: Connection refused
        Is the server running on host "127.0.0.1" and accepting
        TCP/IP connections on port 5432?

DB_URL 是用于设置 Postgre 数据库的环境变量。 在我的本地计算机上，一切似乎都运行良好。 我究竟做错了什么？

UPD：这是我的 Dockerfile。

FROM python:3.7-alpine3.7

WORKDIR /app

COPY requirements.txt ./
RUN \
 apk add --no-cache postgresql-libs && \
 apk add --no-cache --virtual .build-deps gcc musl-dev postgresql-dev && \
 python3 -m pip install -r requirements.txt --no-cache-dir && \
 apk --purge del .build-deps

RUN export PYTHONPATH='${PYTHONPATH}:/app'

COPY . .

CMD ["python", "./run.py"]

Answer 1

这可能会有所帮助。 如果没有，您可能需要向防火墙添加规则以允许来自 docker0 的连接。 在 Linux 上，这是：

# iptables -A INPUT -i docker0 -j ACCEPT

OSX 和 windows 具有访问其防火墙规则的接口。 虽然可以使用命令行修改它们的规则，但众所周知它们会导致显示界面出现错误。