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::advisorynotifications_v1::
AdvisoryNotificationsServiceClient(
google::cloud::advisorynotifications_v1::
MakeAdvisoryNotificationsServiceConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 interacting with Google Cloud Services, specifically within the context of C++ client libraries.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version available is 2.37.0-rc, but this page also includes links to documentation for versions ranging from 2.36.0 down to 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eUsers can override the default \u003ca href=\"https://cloud.google.com/docs/authentication#adc\"\u003eApplication Default Credentials\u003c/a\u003e by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe provided example demonstrates how to explicitly load a service account key file for authentication and a link to best practices is provided.\u003c/p\u003e\n"],["\u003cp\u003eAdditional information can be found about authentication components through the provided link to \u003ca href=\"https://cloud.google.com/cpp/docs/reference/common/latest/group__guac.html\"\u003eAuthentication Components\u003c/a\u003e.\u003c/p\u003e\n"]]],[],null,[]]
