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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eThis page lists the available versions of the C++ client library for Google Cloud Datastore, ranging from version 2.15.1 up to the release candidate 2.37.0-rc, and the currently selected version is 2.24.0.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials (ADC) for authentication, but this can be overridden if necessary.\u003c/p\u003e\n"],["\u003cp\u003eTo override the default credentials, you can provide the UnifiedCredentialsOption, with an example showing how to load a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for other \u003ccode\u003e*Client\u003c/code\u003e classes, specifically \u003ccode\u003edatastore_admin_v1::DatastoreAdminClient\u003c/code\u003e and \u003ccode\u003edatastore_v1::DatastoreClient\u003c/code\u003e, are provided for overriding credentials.\u003c/p\u003e\n"],["\u003cp\u003eFor further information, you can refer to the best practices guide for managing service account keys and the Authentication Components section.\u003c/p\u003e\n"]]],[],null,[]]
