Heroku：使用 RQ 的 Python 后台任务

Posted 2023-02-24

【中文标题】Heroku：使用 RQ 的 Python 后台任务

【英文标题】：Heroku: Background Tasks in Python with RQ

【发布时间】：2017-09-29 16:36:03

【问题描述】：

我正在尝试使用 Heroku 为我的 Django 应用设置后台任务。

我正在按照Heroku documentation 中说明的步骤进行操作。 但是，我一开始就被卡住了。

我已成功安装 RQ：

pip install rq

我创建了worker.py 文件，其中包含与文档中完全相同的代码。

但是，当我尝试运行时：

python worker.py

我收到以下错误：

Traceback (most recent call last):
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 439, in connect
    sock = self._connect()
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 494, in _connect
    raise err
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 482, in _connect
    sock.connect(socket_address)
ConnectionRefusedError: [Errno 61] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/client.py", line 572, in execute_command
    connection.send_command(*args)
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 563, in send_command
    self.send_packed_command(self.pack_command(*args))
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 538, in send_packed_command
    self.connect()
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 442, in connect
    raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error 61 connecting to localhost:6379. Connection refused.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 439, in connect
    sock = self._connect()
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 494, in _connect
    raise err
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 482, in _connect
    sock.connect(socket_address)
ConnectionRefusedError: [Errno 61] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "worker.py", line 15, in <module>
    worker.work()
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/rq/worker.py", line 433, in work
    self.register_birth()
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/rq/worker.py", line 250, in register_birth
    if self.connection.exists(self.key) and \
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/client.py", line 855, in exists
    return self.execute_command('EXISTS', name)
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/client.py", line 578, in execute_command
    connection.send_command(*args)
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 563, in send_command
    self.send_packed_command(self.pack_command(*args))
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 538, in send_packed_command
    self.connect()
  File "/Users/MyUser/my_app/lib/python3.5/site-packages/redis/connection.py", line 442, in connect
    raise ConnectionError(self._error_message(e))
redis.exceptions.ConnectionError: Error 61 connecting to localhost:6379. Connection refused.

经过一番研究，我意识到REDISTOGO_URL 没有配置。我现在已经安装了redistogo，在运行heroku config 时我可以找到它。不幸的是，这似乎不是我做错的唯一事情，因为我仍然遇到同样的错误。

我也尝试按照here 的建议将localhost 更改为127.0.0.1，但没有帮助。

在我发现的所有其他相关问题中，本地服务器上都没有出现问题。

我缺少哪些步骤？

【参考方案1】：

您将 Heroku 上的生产应用程序与本地开发环境混淆了。 RedisToGo 是在 Heroku 上配置的，但是当您在开发机器上运行它时，环境变量不存在，因此它会尝试查找本地运行的 Redis 实例。

您可以在开发机器上安装 Redis，也可以在本地配置 REDISTOGO_URL 环境变量。

【讨论】：

我以为这是我在本地开发环境中运行pip install rq 时完成的...你能告诉我应该如何安装它或如何在本地配置 REDISTOGO_URL 环境变量吗？

好的，我想出了一个办法：我使用了运行命令heroku config 时得到的REDISTOGO_URL 而不是redis://localhost:6379，它似乎正在工作。谢谢！