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::datastore_admin_v1::DatastoreAdminClient(
google::cloud::datastore_admin_v1::MakeDatastoreAdminConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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."],[[["\u003cp\u003eThe latest version available is 2.37.0-rc, with a history of versions down to 2.15.1 accessible via links.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries typically use Application Default Credentials, but these can be overridden using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eService account key files can be loaded to override the default credentials, as demonstrated in the provided code example.\u003c/p\u003e\n"],["\u003cp\u003eExamples for overriding credentials are provided for both \u003ccode\u003edatastore_admin_v1::DatastoreAdminClient\u003c/code\u003e and \u003ccode\u003edatastore_v1::DatastoreClient\u003c/code\u003e classes.\u003c/p\u003e\n"],["\u003cp\u003eFor best practices on managing service account keys, users are directed to the relevant Google Cloud documentation, while \u003ccode\u003eAuthentication Components\u003c/code\u003e provides information for creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
