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"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-03-14 UTC."],[[["This page provides documentation for various versions of the Google Cloud C++ client library, ranging from version 2.11.0 up to the latest release candidate 2.37.0-rc."],["The primary focus of this content is on how to override the default authentication credentials using `UnifiedCredentialsOption` in Google Cloud C++ client libraries."],["By providing a service account key file, users can explicitly load and utilize it for authentication, as shown in the provided C++ code example."],["Examples are provided for both `trace_v1::TraceServiceClient` and `trace_v2::TraceServiceClient` classes on how to implement the service account override."],["Users are directed to best practices for managing service account keys and are given a link to find out more about the factory functions used to create `google::cloud::Credentials` objects."]]],[]]
