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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-09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 document details how to override the default Application Default Credentials (ADC) for authenticating with Google Cloud Services."],["The latest release available is version 2.37.0-rc, and a range of other versions are available, down to version 2.11.0."],["Overriding authentication is done by providing the `UnifiedCredentialsOption`, such as by explicitly loading a service account key file."],["Examples are provided for several `*Client` classes, including `osconfig_agentendpoint_v1::AgentEndpointServiceClient`, `osconfig_v1::OsConfigServiceClient`, and `osconfig_v1::OsConfigZonalServiceClient`."],["For detailed guidance on managing service account keys, refer to the \"Best practices for managing service account keys\" document."]]],[]]
