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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 multiple preceding versions ranging from 2.36.0 down to 2.15.1.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries primarily use Application Default Credentials for authentication with Google Cloud Services, but these defaults can be overridden.\u003c/p\u003e\n"],["\u003cp\u003eOverriding default credentials can be achieved by providing the UnifiedCredentialsOption, such as loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for how to use the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e with the \u003ccode\u003eDatastoreAdminClient\u003c/code\u003e and the \u003ccode\u003eDatastoreClient\u003c/code\u003e are provided on the page.\u003c/p\u003e\n"],["\u003cp\u003eFor best practices regarding service account keys, users are directed to the official guide and for more information on the creation of credentials to the Authentication Components documentation.\u003c/p\u003e\n"]]],[],null,[]]
