Unless otherwise configured, the client libraries use Application Default Credentials to authenticate with Google Cloud Services. While this works for most applications, in some cases you may need to override this default. You can do so by providing the UnifiedCredentialsOption The following example shows how to explicitly load a service account key file:
[](std::string const& keyfile) {
auto is = std::ifstream(keyfile);
is.exceptions(std::ios::badbit); // Minimal error handling in examples
auto contents = std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
auto options =
google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
google::cloud::MakeServiceAccountCredentials(contents));
return google::cloud::apigateway_v1::ApiGatewayServiceClient(
google::cloud::apigateway_v1::MakeApiGatewayServiceConnection(options));
}
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThis webpage provides documentation for overriding authentication credentials when using Google Cloud client libraries, specifically for the API Gateway service, with version information ranging from 2.11.0 to 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries typically use Application Default Credentials, but this can be overridden using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e for specific authentication needs.\u003c/p\u003e\n"],["\u003cp\u003eA service account key file can be explicitly loaded to override default credentials, as demonstrated in the provided C++ code example.\u003c/p\u003e\n"],["\u003cp\u003eThe webpage links to additional resources on authentication components and best practices for managing service account keys, offering further guidance.\u003c/p\u003e\n"],["\u003cp\u003eThe most recent release candidate version of the documentation is version 2.37.0-rc, and is documented with the same information, about overriding the authentication credentials as the rest of the documented versions.\u003c/p\u003e\n"]]],[],null,[]]
