python - 在 AWS lambda 上运行时出现无法打开数据库文件错误

Question

我在程序中使用 coinmarketcap，并且已将该库正确安装到已上传到我的 aws lambda 函数的部署包中。但是，即使代码在我的计算机上本地运行，在 aws lambda 上运行时它也会返回以下错误消息:

{
  "stackTrace": [
    [
      "/var/task/main.py",
      11,
      "lambda_handler",
      "return on_intent(event[\"request\"], event[\"session\"])"
    ],
    [
      "/var/task/main.py",
      50,
      "on_intent",
      "data = coinmarketcap.ticker('Bitcoin', limit=3, convert='USD')"
    ],
    [
      "/var/task/coinmarketcap/core.py",
      54,
      "ticker",
      "response = self.__request('ticker/' + currency, params)"
    ],
    [
      "/var/task/coinmarketcap/core.py",
      28,
      "__request",
      "response_object = self.session.get(self.base_url + endpoint, params = params, timeout = self.request_timeout)"
    ],
    [
      "/var/task/coinmarketcap/core.py",
      21,
      "session",
      "self._session = requests_cache.core.CachedSession(cache_name='coinmarketcap_cache', backend='sqlite', expire_after=120)"
    ],
    [
      "/var/task/requests_cache/core.py",
      68,
      "__init__",
      "self.cache = backends.create_backend(backend, cache_name, backend_options)"
    ],
    [
      "/var/task/requests_cache/backends/__init__.py",
      50,
      "create_backend",
      "return registry[backend_name](cache_name, **options)"
    ],
    [
      "/var/task/requests_cache/backends/sqlite.py",
      28,
      "__init__",
      "self.responses = DbPickleDict(location + extension, 'responses', fast_save=fast_save)"
    ],
    [
      "/var/task/requests_cache/backends/storage/dbdict.py",
      58,
      "__init__",
      "with self.connection() as con:"
    ],
    [
      "/usr/lib64/python2.7/contextlib.py",
      17,
      "__enter__",
      "return self.gen.next()"
    ],
    [
      "/var/task/requests_cache/backends/storage/dbdict.py",
      70,
      "connection",
      "con = sqlite.connect(self.filename)"
    ]
  ],
  "errorType": "OperationalError",
  "errorMessage": "unable to open database file"
}

代码:

Was Here

知道为什么会发生这种情况吗？

Answer 1

尝试在 /var/task/ 中创建名为 coinmarketcap_cache.sqlite 的本地文件时，coinmarketcap-api 代码(查看 here )失败(您会在您的本地计算机上找到它，这就是它在本地工作的原因)。

AWS Lambda 没有对 /var/task/ 的写入权限。但是，它具有对/tmp/ 的写访问权限。遗憾的是，coinmarketcap-api 不支持更改该文件的位置，这让您几乎没有选择:

尝试更改代码最顶层的当前目录。

import os
os.chdir("/tmp")