Fixing Google BigQuery Auth Proxying

builder.Credential = credential;

• Fails to route authentication traffic through the proxy.builder.GoogleCredential = credential;
• Successfully routes OAuth token requests through the proxy.If your C# application runs behind a proxy, you have probably run into an annoying issue with the Google BigQuery client libraries: your BigQuery query calls route through the proxy perfectly by setting the HttpClientFactory property on the BigQueryClientBuilder , but the authentication and token refresh requests ignore the proxy entirely and attempt to hit the standard network, causing timeouts. To resolve this, set a proxied GoogleCredential to the GoogleCredential property instead of the Credential property on the client builder. Example code:

using System.Net;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Http;
using Google.Cloud.BigQuery.V2;
// 1. Configure your proxy
IWebProxy proxySettings = new WebProxy("http://your-proxy-host:8080", bypassOnLocal: true)
{
Credentials = new NetworkCredential("username", "password")
};
// 2. Wrap it inside Google's API HttpClientFactory

HttpClientFactory proxyClientFactory = HttpClientFactory.ForProxy(proxySettings);

// 3. Load credentials and create a new credential using the proxied http client factory
GoogleCredential credential = await GoogleCredential.FromFileAsync("path/to/service-account.json");
credential = credential.CreateWithHttpClientFactory(proxyClientFactory);
// 4. Construct the client

BigQueryClient bigQueryClient = new BigQueryClientBuilder

{
ProjectId = "your-google-cloud-project-id",

HttpClientFactory = proxyClientFactory, // Proxies BigQuery data calls GoogleCredential = credential // CRITICAL: Proxies Auth/token calls }.Build();