ServiceUnavailable：503 DNS解析服务失败：firestore.googleapis.com

Question

我正在尝试使用 Python 代码（在 Jupyter Notebook 中）在我的项目中访问 Google 的 Firestore，但由于某种原因，Python 程序永远不会完成。 还尝试在 Firestore 中创建文档，但随后出现此错误：

ServiceUnavailable: 503 DNS resolution failed for service: firestore.googleapis.com

我在 Firestore 中创建了一个服务帐户（ServiceAccount.json 包含设置）。这是我的代码：

import firebase_admin

from firebase_admin import credentials
from firebase_admin import firestore

cred = credentials.Certificate('ServiceAccount.json')
firebase_admin.initialize_app(cred)
db = firestore.client()
db.collection('company').add({'name': 'Test'})

只有最后一条语句失败。 这也被返回：

_InactiveRpcError                         Traceback (most recent call last)
C:\ProgramData\Anaconda3\lib\site-packages\google\api_core\grpc_helpers.py in error_remapped_callable(*args, **kwargs)
     65         try:
---> 66             return callable_(*args, **kwargs)
     67         except grpc.RpcError as exc:

C:\ProgramData\Anaconda3\lib\site-packages\grpc\_channel.py in __call__(self, request, timeout, metadata, credentials, wait_for_ready, compression)
    945                                       wait_for_ready, compression)
--> 946         return _end_unary_response_blocking(state, call, False, None)
    947 

C:\ProgramData\Anaconda3\lib\site-packages\grpc\_channel.py in _end_unary_response_blocking(state, call, with_call, deadline)
    848     else:
--> 849         raise _InactiveRpcError(state)
    850 

_InactiveRpcError: <_InactiveRpcError of RPC that terminated with:
    status = StatusCode.UNAVAILABLE
    details = "DNS resolution failed for service: firestore.googleapis.com"
    debug_error_string = "{"created":"@1632831473.221000000","description":"Resolver transient failure","file":"src/core/ext/filters/client_channel/client_channel.cc","file_line":1356,"referenced_errors":[{"created":"@1632831473.221000000","description":"DNS resolution failed for service: firestore.googleapis.com","file":"src/core/ext/filters/client_channel/resolver/dns/native/dns_resolver.cc","file_line":202,"grpc_status":14,"referenced_errors":[{"created":"@1632831473.221000000","description":"OS Error","file":"src/core/lib/iomgr/resolve_address_windows.cc","file_line":93,"os_error":"The specified class was not found.\r\n","syscall":"getaddrinfo","wsa_error":10109}]}]}"
>

The above exception was the direct cause of the following exception:

ServiceUnavailable                        Traceback (most recent call last)
C:\ProgramData\Anaconda3\lib\site-packages\google\api_core\retry.py in retry_target(target, predicate, sleep_generator, deadline, on_error)
    189         try:
--> 190             return target()
    191
...

Answer 1

您使用的是 Windows 吗？如果你是，我相信你已经打了bug。虽然 c-ares DNS 解析器问题已得到修复，但您可能使用的是较旧的软件包。

您可以通过检查已配置的环境变量来解决此问题。如果您在 Jupyter Notebook 单元之一中运行它：

import os
os.environ

您应该得到一长串变量。看看GRPC_DNS_RESOLVER是什么：

environ{'SHELL': '/bin/bash',
        'OS_IMAGE_FAMILY': 'debian-10',
        'CONDA_EXE': '/opt/conda/bin/conda',
        '_CE_M': '',
        'DL_ANACONDA_HOME': '/opt/conda',

根据documentation：

GRPC_DNS_RESOLVER 声明使用哪个 DNS 解析器。如果 gRPC 是使用 c-ares 支持构建的，则默认值为 ares。否则，此环境变量的值将被忽略。可用的 DNS 解析器包括：

ares（除 iOS、Android 或 Node 之外的大多数平台上的默认设置）- 基于 c-ares 库的 DNS 解析器

native - 基于 getaddrinfo() 的 DNS 解析器，创建一个新线程来执行名称解析

然后您可以像这样将GRPC_DNS_RESOLVER 设置为原生：

os.environ['GRPC_DNS_RESOLVER'] = 'native'