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::serviceusage_v1::ServiceUsageClient(
google::cloud::serviceusage_v1::MakeServiceUsageConnection(options));
}
[[["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."],[[["The latest available version is 2.37.0-rc, with multiple other versions, down to 2.11.0, also listed for reference."],["The client libraries use Application Default Credentials (ADC) by default for authentication with Google Cloud Services."],["You can override the default authentication credentials using `UnifiedCredentialsOption`, such as by loading a service account key file."],["The provided example demonstrates how to load a service account key file for authentication using `MakeServiceAccountCredentials`, but it's suggested to also refer to the best practices guide for managing service account keys."],["The Authentication Components link provides information on the factory functions to create `google::cloud::Credentials` objects."]]],[]]
