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 2025-03-21 UTC."],[[["This page provides documentation for overriding default authentication credentials when using Google Cloud C++ client libraries."],["The latest release candidate version is 2.37.0-rc, with a range of past versions from 2.36.0 down to 2.11.0 also accessible."],["You can override the default Application Default Credentials by using the `UnifiedCredentialsOption` and explicitly loading a service account key file, as demonstrated in the example."],["Examples for using service account credentials can be found for `trace_v1::TraceServiceClient` and `trace_v2::TraceServiceClient`."],["For detailed information on creating `google::cloud::Credentials` objects and the management of service account keys, refer to the \"Authentication Components\" and \"Best practices for managing service account keys\" guides, respectively."]]],[]]
