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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThis page documents various versions of the C++ Trace API, ranging from version 2.11.0 up to the latest release candidate 2.37.0-rc, with links to specific documentation for each version.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials for Google Cloud Services authentication, but this default can be overridden.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication method by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as loading a service account key file explicitly.\u003c/p\u003e\n"],["\u003cp\u003eExamples of overriding authentication credentials for \u003ccode\u003etrace_v1::TraceServiceClient\u003c/code\u003e and \u003ccode\u003etrace_v2::TraceServiceClient\u003c/code\u003e are available via the provided links.\u003c/p\u003e\n"],["\u003cp\u003eThe page directs users to consult the "Best practices for managing service account keys" guide for enhanced security and to the "Authentication Components" section for additional credential creation methods.\u003c/p\u003e\n"]]],[],null,[]]
