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::config_v1::ConfigClient(
google::cloud::config_v1::MakeConfigConnection(options));
}
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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."],[[["\u003cp\u003eThis page provides documentation for overriding default authentication credentials when interacting with Google Cloud Services, offering examples and version specific documentation.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials, but users can override this by using the UnifiedCredentialsOption, as demonstrated in the provided code example.\u003c/p\u003e\n"],["\u003cp\u003eThe code example showcases how to explicitly load credentials from a service account key file, which is an effective way to manage credentials.\u003c/p\u003e\n"],["\u003cp\u003eThere are multiple version-specific pages ranging from 2.16.0 to 2.37.0-rc, that can be accessed to see details pertaining to each respective version.\u003c/p\u003e\n"],["\u003cp\u003eThe page references best practices for managing service account keys and points to Authentication Components for further details on credential object creation.\u003c/p\u003e\n"]]],[],null,[]]
