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::trace_v1::TraceServiceClient(
google::cloud::trace_v1::MakeTraceServiceConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThe webpage provides documentation for overriding default authentication credentials when interacting with Google Cloud Services, using Application Default Credentials.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version available is 2.37.0-rc, and the documentation lists multiple past versions, ranging back to version 2.11.0, allowing users to review changes and updates over time.\u003c/p\u003e\n"],["\u003cp\u003eUsers can override the default authentication by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, demonstrated through an example that loads a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe content provides links to specific examples for \u003ccode\u003etrace_v1::TraceServiceClient\u003c/code\u003e and \u003ccode\u003etrace_v2::TraceServiceClient\u003c/code\u003e to help with implementation.\u003c/p\u003e\n"],["\u003cp\u003eThe page also references and recommends the "Best practices for managing service account keys" guide for more security details and the "Authentication Components" page for more details on factory functions.\u003c/p\u003e\n"]]],[],null,[]]
