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::policytroubleshooter_iam_v3::
PolicyTroubleshooterClient(
google::cloud::policytroubleshooter_iam_v3::
MakePolicyTroubleshooterConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 the Policy Troubleshooter service, with version 2.37.0-rc being the latest release candidate, and version 2.29.0 is the current version referenced on this page.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation covers how to override default authentication credentials using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, allowing the explicit loading of a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe example provided demonstrates the process of loading a service account key file, using minimal error handling, and using \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e within the \u003ccode\u003egoogle::cloud::Options\u003c/code\u003e and \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThere are links to code examples that show how to override authentication for other client classes, such as \u003ccode\u003epolicytroubleshooter_iam_v3::PolicyTroubleshooterClient\u003c/code\u003e and \u003ccode\u003epolicytroubleshooter_v1::IamCheckerClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe Best practices for managing service account keys guide and the Authentication components documentation is provided for more details.\u003c/p\u003e\n"]]],[],null,[]]
