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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 document provides version-specific documentation for the C++ Datastore client library, with version 2.37.0-rc as the latest release candidate and 2.34.0 being the current default view.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials for authentication with Google Cloud Services, but this behavior can be overridden.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and explicitly loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided for how to use service account credentials with the \u003ccode\u003edatastore_admin_v1::DatastoreAdminClient\u003c/code\u003e and \u003ccode\u003edatastore_v1::DatastoreClient\u003c/code\u003e classes.\u003c/p\u003e\n"],["\u003cp\u003eThe document references best practices and further documentation on how to manage service account keys and create \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
