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::tasks_v2::CloudTasksClient(
google::cloud::tasks_v2::MakeCloudTasksConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe latest version for overriding authentication tasks is 2.37.0-rc, with several preceding versions available, from 2.36.0 down to 2.11.0, each linked to specific documentation.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries typically use Application Default Credentials for authentication with Google Cloud Services, but these can be overridden when necessary.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e allows you to override default credentials, as demonstrated by the example using a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eService account keys can be explicitly loaded through the method demonstrated in the provided example, by loading the files with \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e and setting \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e in \u003ccode\u003egoogle::cloud::Options\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eFor further information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects, you can refer to the Authentication Components documentation.\u003c/p\u003e\n"]]],[],null,[]]
