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::gkeconnect_gateway_v1::GatewayControlClient(
google::cloud::gkeconnect_gateway_v1::MakeGatewayControlConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-09 UTC."],[[["This page details how to override the default Application Default Credentials used by client libraries for authenticating with Google Cloud Services."],["The most recent release candidate for this component is version 2.37.0-rc, with version 2.29.0 being the oldest shown here."],["Overriding authentication is done by providing the `UnifiedCredentialsOption`, demonstrated through the loading of a service account key file."],["The `Authentication Components` documentation provides additional information on creating `google::cloud::Credentials` objects."],["For managing service account keys it is recommended to consult the documentation, `Best practices for managing service account keys`."]]],[]]
