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::osconfig_agentendpoint_v1::AgentEndpointServiceClient(
google::cloud::osconfig_agentendpoint_v1::
MakeAgentEndpointServiceConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-09 UTC."],[[["This webpage details how to override the default Application Default Credentials for authenticating with Google Cloud Services, particularly for C++ client libraries."],["The latest release candidate version available is 2.37.0-rc, with a history of versions ranging down to 2.11.0, all of which are accessible through the provided links."],["The primary method for overriding credentials involves using the `UnifiedCredentialsOption` and loading a service account key file as demonstrated in the code example."],["Links are provided to examples for the `osconfig_agentendpoint_v1::AgentEndpointServiceClient` and `osconfig_v1::OsConfigServiceClient` classes, showcasing service account credential usage."],["Best practices for managing service account keys and further information on `google::cloud::Credentials` objects are available through external links."]]],[]]