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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 page provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically focusing on the \u003ccode\u003eApiGateway\u003c/code\u003e service.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version available is \u003ccode\u003e2.37.0-rc\u003c/code\u003e, while \u003ccode\u003e2.27.0\u003c/code\u003e is where the listed version information starts, and this page provides a history of the versions in between.\u003c/p\u003e\n"],["\u003cp\u003eUsers can override the default authentication by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, which enables specifying credentials directly.\u003c/p\u003e\n"],["\u003cp\u003eAn example is provided that demonstrates how to load a service account key file to explicitly authenticate, but users are encouraged to consult best practices for managing service account keys for more details.\u003c/p\u003e\n"],["\u003cp\u003eAdditional information about creating \u003ccode\u003eCredentials\u003c/code\u003e objects can be found in the linked "Authentication Components" section.\u003c/p\u003e\n"]]],[],null,[]]
