PYTHON-5555 Fix AWS Lambda build

[blink1073]

Updated to use Python 3.10, which solved a dns resolve error on lambda.

I did not find the root cause, but since 3.9 is EOL next month I left it at this solution.

I also updated the errors raised by srv_resolver to include the original error, which was useful in debugging the problem.

Passing build: https://spruce.mongodb.com/task/mongo_python_driver_faas_lambda_test_aws_lambda_deployed_patch_eca38b730b8227c52cd5f0c655f617e969743ee1_68c9e481e31406000770e31e_25_09_16_22_28_25/logs?execution=0

[aclark4life]

Nice

[ShaneHarvey]

I did not find the root cause, but since 3.9 is EOL next month I left it at this solution.

Did you find the full trackback of the unsupported operand type(s) for |: 'type' and 'NoneType' error? Sounds like some code is incorrectly using PEP-604 on Python 3.9.

[ShaneHarvey]

Found in your patch:

[2025/09/16 12:41:50.285] {"errorMessage": "['Traceback (most recent call last):\\n',
 '  File \"/var/task/pymongo/synchronous/srv_resolver.py\", line 117, in _resolve_uri\\n    results = _resolve(\\n',
 '  File \"/var/task/pymongo/synchronous/srv_resolver.py\", line 51, in _resolve\\n    from dns import resolver\\n',
 '  File \"/var/task/dns/resolver.py\", line 30, in <module>\\n    import dns._ddr\\n',
 '  File \"/var/task/dns/_ddr.py\", line 9, in <module>\\n    import dns.asyncbackend\\n',
 '  File \"/var/task/dns/asyncbackend.py\", line 5, in <module>\\n    import dns.exception\\n',
 '  File \"/var/task/dns/exception.py\", line 28, in <module>\\n    class DNSException(Exception):\\n',
 '  File \"/var/task/dns/exception.py\", line 51, in DNSException\\n    msg: str | None = None  # non-parametrized message\\n',
 \"TypeError: unsupported operand type(s) for |: 'type' and 'NoneType'\\n\"]", "errorType": "ConfigurationError", "requestId": "", "stackTrace": ["  File \"/var/lang/lib/python3.9/importlib/__init__.py\", line 127, in import_module\n    return _bootstrap._gcd_import(name[level:], package, level)\n",
 "  File \"<frozen importlib._bootstrap>\", line 1030, in _gcd_import\n",
 "  File \"<frozen importlib._bootstrap>\", line 1007, in _find_and_load\n",
 "  File \"<frozen importlib._bootstrap>\", line 986, in _find_and_load_unlocked\n",
 "  File \"<frozen importlib._bootstrap>\", line 680, in _load_unlocked\n",
 "  File \"<frozen importlib._bootstrap_external>\", line 850, in exec_module\n",
 "  File \"<frozen importlib._bootstrap>\", line 228, in _call_with_frames_removed\n",
 "  File \"/var/task/app.py\", line 119, in <module>\n    client.lambdaTest.list_collections()\n",
 "  File \"/var/task/pymongo/synchronous/database.py\", line 1182, in list_collections\n    return self._list_collections_helper(session, filter, comment, **kwargs)\n",
 "  File \"/var/task/pymongo/synchronous/database.py\", line 1143, in _list_collections_helper\n    return self._client._retryable_read(\n",
 "  File \"/var/task/pymongo/synchronous/mongo_client.py\", line 2047, in _retryable_read\n    return self._retry_internal(\n",
 "  File \"/var/task/pymongo/_csot.py\", line 125, in csot_wrapper\n    return func(self, *args, **kwargs)\n",
 "  File \"/var/task/pymongo/synchronous/mongo_client.py\", line 2003, in _retry_internal\n    return _ClientConnectionRetryable(\n",
 "  File \"/var/task/pymongo/synchronous/mongo_client.py\", line 2765, in run\n    return self._read() if self._is_read else self._write()\n",
 "  File \"/var/task/pymongo/synchronous/mongo_client.py\", line 2910, in _read\n    self._server = self._get_server()\n",
 "  File \"/var/task/pymongo/synchronous/mongo_client.py\", line 2858, in _get_server\n    return self._client._select_server(\n",
 "  File \"/var/task/pymongo/synchronous/mongo_client.py\", line 1820, in _select_server\n    topology = self._get_topology()\n",
 "  File \"/var/task/pymongo/synchronous/mongo_client.py\", line 1758, in _get_topology\n    self._resolve_srv()\n",
 "  File \"/var/task/pymongo/synchronous/mongo_client.py\", line 910, in _resolve_srv\n    res = uri_parser._parse_srv(\n",
 "  File \"/var/task/pymongo/synchronous/uri_parser.py\", line 168, in _parse_srv\n    nodes = dns_resolver.get_hosts()\n",
 "  File \"/var/task/pymongo/synchronous/srv_resolver.py\", line 161, in get_hosts\n    _, nodes = self._get_srv_response_and_hosts(True)\n",
 "  File \"/var/task/pymongo/synchronous/srv_resolver.py\", line 135, in _get_srv_response_and_hosts\n    results = self._resolve_uri(encapsulate_errors)\n",
 "  File \"/var/task/pymongo/synchronous/srv_resolver.py\", line 127, in _resolve_uri\n    raise ConfigurationError(\n"]}Exiting due to FunctionError!

It seems the task has installed dnspython 2.7.0:

 [2025/09/16 12:40:32.070] Collecting dnspython<3.0.0,>=1.16.0 (from pymongo==4.16.0.dev0)
 [2025/09/16 12:40:32.070]   Obtaining dependency information for dnspython<3.0.0,>=1.16.0 from https://files.pythonhosted.org/packages/68/1b/e0a87d256e40e8c888847551b20a017a6b98139178505dc7ffb96f04e954/dnspython-2.7.0-py3-none-any.whl.metadata
 [2025/09/16 12:40:32.092]   Downloading dnspython-2.7.0-py3-none-any.whl.metadata (5.8 kB)
 [2025/09/16 12:40:32.092] Downloading dnspython-2.7.0-py3-none-any.whl (313 kB)

But the AWS Function ends up using a later version of dnspython that has already dropped support for 3.9:

 '  File \"/var/task/dns/exception.py\", line 51, in DNSException\\n    msg: str | None = None  # non-parametrized message\\n',

https://spruce.mongodb.com/task/mongo_python_driver_faas_lambda_test_aws_lambda_deployed_patch_eca38b730b8227c52cd5f0c655f617e969743ee1_68c9b9854bb28a0007594d02_25_09_16_19_25_02/logs?execution=0

Whereas dnspython 2.7.0 looks like this:

    msg: Optional[str] = None  # non-parametrized message

https://github.com/rthalley/dnspython/blob/v2.7.0/dns/exception.py#L51

[blink1073]

Thanks for tracking that down!