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::run_v2::ExecutionsClient(
google::cloud::run_v2::MakeExecutionsConnection(options));
}
Follow these links to find examples for other *Client classes:
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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, which typically rely on Application Default Credentials.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as demonstrated with an example of loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe content covers multiple versions of the client libraries, from version 2.11.0 up to the latest release candidate 2.37.0-rc, including version 2.17.0.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding authentication are provided for several \u003ccode\u003e*Client\u003c/code\u003e classes including \u003ccode\u003erun_v2::ExecutionsClient\u003c/code\u003e, \u003ccode\u003erun_v2::JobsClient\u003c/code\u003e, \u003ccode\u003erun_v2::RevisionsClient\u003c/code\u003e, \u003ccode\u003erun_v2::ServicesClient\u003c/code\u003e, and \u003ccode\u003erun_v2::TasksClient\u003c/code\u003e, specifically for version 2.17.0.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation recommends consulting the "Best practices for managing service account keys" guide for more information, and it also provides a link to the "Authentication Components" for further details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
