(psycopg2.OperationalError) 无法连接到服务器：连接被拒绝是服务器
(psycopg2.OperationalError) could not connect to server: Connection refused Is the server
我正在尝试连接两个 docker 容器，一个是 posgresql，另一个是 python flask 应用程序。两者都正确链接，python 应用程序中的所有连接变量都直接取自通过链接公开的 postgres 容器中的变量，并且与检查 postgresql 容器时发现的变量相同。当我将 psql 与连接字符串中的确切参数一起使用时，即：
psql -p 5432 -h 172.17.0.2 -d mydb -U user
连接到 postgres 容器中的数据库成功，所以我知道 postgres 通过指定的端口等正确通信。但是，当我尝试使用相同的连接变量通过 flask 连接到数据库时，我得到了这个错误：
Traceback (most recent call last): File
"/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line
1122, in _do_get
return self._pool.get(wait, self._timeout) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/queue.py",
line 145, in get
raise Empty sqlalchemy.util.queue.Empty
During handling of the above exception, another exception occurred:
Traceback (most recent call last): File
"/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py",
line 2138, in _wrap_pool_connect
return fn() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 328,
in unique_connection
return _ConnectionFairy._checkout(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 766,
in _checkout
fairy = _ConnectionRecord.checkout(pool) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 516,
in checkout
rec = pool._do_get() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line
1138, in _do_get
self._dec_overflow() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/langhelpers.py",
line 60, in exit
compat.reraise(exc_type, exc_value, exc_tb) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/compat.py",
line 187, in reraise
raise value File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line
1135, in _do_get
return self._create_connection() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 333,
in _create_connection
return _ConnectionRecord(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 461,
in init
self.connect(first_connect_check=True) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 651,
in __connect
connection = pool._invoke_creator(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/strategies.py",
line 105, in connect
return dialect.connect(*cargs, **cparams) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/default.py",
line 393, in connect
return self.dbapi.connect(*cargs, **cparams) File "/usr/local/lib/python3.6/site-packages/psycopg2/__init.py", line
164, in connect
conn = _connect(dsn, connection_factory=connection_factory, async=async) psycopg2.OperationalError: could not connect to server:
Connection refused Is the server running on host "172.17.0.2" 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 "./wsgi.py", line 14, in
app = getModule("/var/www", name).app File "./wsgi.py", line 5, in getModule
return imp.load_source(module, ("%s/%s.py" % (path, name))) File "/usr/local/lib/python3.6/imp.py", line 172, in load_source
module = _load(spec) File "/var/www/backend.py", line 3, in
import json, logging, db, os File "/var/www/db.py", line 36, in
engine.connect() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py",
line 2082, in connect
return self._connection_cls(self, **kwargs) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py",
line 90, in init
if connection is not None else engine.raw_connection() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py",
line 2168, in raw_connection
self.pool.unique_connection, _connection) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py",
line 2142, in _wrap_pool_connect
e, dialect, self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py",
line 1456, in _handle_dbapi_exception_noconnection
exc_info File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/compat.py",
line 203, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb, cause=cause) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/compat.py",
line 186, in reraise
raise value.with_traceback(tb) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py",
line 2138, in _wrap_pool_connect
return fn() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 328,
in unique_connection
return _ConnectionFairy._checkout(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 766,
in _checkout
fairy = _ConnectionRecord.checkout(pool) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 516,
in checkout
rec = pool._do_get() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line
1138, in _do_get
self._dec_overflow() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/langhelpers.py",
line 60, in exit
compat.reraise(exc_type, exc_value, exc_tb) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/compat.py",
line 187, in reraise
raise value File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line
1135, in _do_get
return self._create_connection() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 333,
in _create_connection
return _ConnectionRecord(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 461,
in init
self.connect(first_connect_check=True) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 651,
in __connect
connection = pool._invoke_creator(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/strategies.py",
line 105, in connect
return dialect.connect(*cargs, **cparams) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/default.py",
line 393, in connect
return self.dbapi.connect(*cargs, **cparams) File "/usr/local/lib/python3.6/site-packages/psycopg2/__init.py", line
164, in connect
conn = _connect(dsn, connection_factory=connection_factory, async=async) sqlalchemy.exc.OperationalError:
(psycopg2.OperationalError) could not connect to server: Connection
refused Is the server running on host "172.17.0.2" and accepting
TCP/IP connections on port 5432?
下面是我的 Flask 应用程序中导致异常的代码：
import os, logging, json
from datetime import datetime
from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy
from sqlalchemy import BigInteger, Integer, String, DateTime, Column, Table, ForeignKey, create_engine
from sqlalchemy.dialects.postgresql import JSON
from sqlalchemy.orm import scoped_session, sessionmaker, relationship
from sqlalchemy.ext.declarative import declarative_base
user = os.environ.get('DB_USER','user')
password = os.environ.get('DB_PASSWORD','password')
address = os.environ.get('DB_ADDR','0.0.0.0')
port = os.environ.get('DB_PORT','')
name = os.environ.get('DB_NAME','')
db_url = "postgresql://%s:%s@%s:%s/%s" % (user, password, address, port, name)
engine = create_engine(db_url, convert_unicode=True, client_encoding='utf8')
print (engine)
engine.connect()
当我记录 "engine" 我得到这个：
Engine(postgresql://user:***@172.17.0.2:5432/mydb)
这再次与我主机上的数据库成功连接数据库时使用的参数相匹配。
我假设我的 python 代码一定有问题，因为所有帐户的 docker 容器都正常工作。
任何帮助将不胜感激，谢谢。
所以我的代码实际上没问题，发生的是竞争条件，其中 python 在数据库完全初始化并接受连接之前发送连接请求。
我正在尝试连接两个 docker 容器，一个是 posgresql，另一个是 python flask 应用程序。两者都正确链接，python 应用程序中的所有连接变量都直接取自通过链接公开的 postgres 容器中的变量，并且与检查 postgresql 容器时发现的变量相同。当我将 psql 与连接字符串中的确切参数一起使用时，即：
psql -p 5432 -h 172.17.0.2 -d mydb -U user
连接到 postgres 容器中的数据库成功，所以我知道 postgres 通过指定的端口等正确通信。但是，当我尝试使用相同的连接变量通过 flask 连接到数据库时，我得到了这个错误：
Traceback (most recent call last): File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 1122, in _do_get return self._pool.get(wait, self._timeout) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/queue.py", line 145, in get raise Empty sqlalchemy.util.queue.Empty
During handling of the above exception, another exception occurred:
Traceback (most recent call last): File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 2138, in _wrap_pool_connect return fn() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 328, in unique_connection return _ConnectionFairy._checkout(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 766, in _checkout fairy = _ConnectionRecord.checkout(pool) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 516, in checkout rec = pool._do_get() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 1138, in _do_get self._dec_overflow() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/langhelpers.py", line 60, in exit compat.reraise(exc_type, exc_value, exc_tb) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 187, in reraise raise value File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 1135, in _do_get return self._create_connection() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 333, in _create_connection return _ConnectionRecord(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 461, in init self.connect(first_connect_check=True) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 651, in __connect connection = pool._invoke_creator(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/strategies.py", line 105, in connect return dialect.connect(*cargs, **cparams) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/default.py", line 393, in connect return self.dbapi.connect(*cargs, **cparams) File "/usr/local/lib/python3.6/site-packages/psycopg2/__init.py", line 164, in connect conn = _connect(dsn, connection_factory=connection_factory, async=async) psycopg2.OperationalError: could not connect to server: Connection refused Is the server running on host "172.17.0.2" 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 "./wsgi.py", line 14, in app = getModule("/var/www", name).app File "./wsgi.py", line 5, in getModule return imp.load_source(module, ("%s/%s.py" % (path, name))) File "/usr/local/lib/python3.6/imp.py", line 172, in load_source module = _load(spec) File "/var/www/backend.py", line 3, in import json, logging, db, os File "/var/www/db.py", line 36, in engine.connect() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 2082, in connect return self._connection_cls(self, **kwargs) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 90, in init if connection is not None else engine.raw_connection() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 2168, in raw_connection self.pool.unique_connection, _connection) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 2142, in _wrap_pool_connect e, dialect, self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 1456, in _handle_dbapi_exception_noconnection exc_info File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 203, in raise_from_cause reraise(type(exception), exception, tb=exc_tb, cause=cause) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 186, in reraise raise value.with_traceback(tb) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/base.py", line 2138, in _wrap_pool_connect return fn() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 328, in unique_connection return _ConnectionFairy._checkout(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 766, in _checkout fairy = _ConnectionRecord.checkout(pool) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 516, in checkout rec = pool._do_get() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 1138, in _do_get self._dec_overflow() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/langhelpers.py", line 60, in exit compat.reraise(exc_type, exc_value, exc_tb) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/util/compat.py", line 187, in reraise raise value File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 1135, in _do_get return self._create_connection() File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 333, in _create_connection return _ConnectionRecord(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 461, in init self.connect(first_connect_check=True) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/pool.py", line 651, in __connect connection = pool._invoke_creator(self) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/strategies.py", line 105, in connect return dialect.connect(*cargs, **cparams) File "/usr/local/lib/python3.6/site-packages/sqlalchemy/engine/default.py", line 393, in connect return self.dbapi.connect(*cargs, **cparams) File "/usr/local/lib/python3.6/site-packages/psycopg2/__init.py", line 164, in connect conn = _connect(dsn, connection_factory=connection_factory, async=async) sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) could not connect to server: Connection refused Is the server running on host "172.17.0.2" and accepting TCP/IP connections on port 5432?
下面是我的 Flask 应用程序中导致异常的代码：
import os, logging, json
from datetime import datetime
from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy
from sqlalchemy import BigInteger, Integer, String, DateTime, Column, Table, ForeignKey, create_engine
from sqlalchemy.dialects.postgresql import JSON
from sqlalchemy.orm import scoped_session, sessionmaker, relationship
from sqlalchemy.ext.declarative import declarative_base
user = os.environ.get('DB_USER','user')
password = os.environ.get('DB_PASSWORD','password')
address = os.environ.get('DB_ADDR','0.0.0.0')
port = os.environ.get('DB_PORT','')
name = os.environ.get('DB_NAME','')
db_url = "postgresql://%s:%s@%s:%s/%s" % (user, password, address, port, name)
engine = create_engine(db_url, convert_unicode=True, client_encoding='utf8')
print (engine)
engine.connect()
当我记录 "engine" 我得到这个：
Engine(postgresql://user:***@172.17.0.2:5432/mydb)
这再次与我主机上的数据库成功连接数据库时使用的参数相匹配。
我假设我的 python 代码一定有问题，因为所有帐户的 docker 容器都正常工作。
任何帮助将不胜感激，谢谢。
所以我的代码实际上没问题，发生的是竞争条件，其中 python 在数据库完全初始化并接受连接之前发送连接请求。