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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["This document provides versioned documentation for the OS Config API, detailing versions from 2.11.0 up to the latest release candidate 2.37.0-rc."],["The guide demonstrates how to override the default Application Default Credentials (ADC) for authenticating with Google Cloud Services using the `UnifiedCredentialsOption`."],["The example provided shows how to load a service account key file explicitly to override the default credentials for authenticating the C++ Client Libraries."],["The documentation includes links to examples for different `*Client` classes, such as `AgentEndpointServiceClient`, `OsConfigServiceClient`, and `OsConfigZonalServiceClient`, each with service account usage examples."],["Users can refer to the \"Best practices for managing service account keys\" guide and the \"Authentication Components\" section for additional information on managing credentials and creating `google::cloud::Credentials` objects."]]],[]]
