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::metastore_v1::DataprocMetastoreClient(
google::cloud::metastore_v1::MakeDataprocMetastoreConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically focusing on the \u003ccode\u003emetastore\u003c/code\u003e service.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version documented is 2.37.0-rc, but this page also provides documentation for versions ranging from 2.13.0 up to 2.36.0.\u003c/p\u003e\n"],["\u003cp\u003eThe default authentication method uses Application Default Credentials, but users can override this by using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e to provide custom credentials, such as a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples are provided demonstrating how to override credentials for \u003ccode\u003emetastore_v1::DataprocMetastoreClient\u003c/code\u003e and \u003ccode\u003emetastore_v1::DataprocMetastoreFederationClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eUsers can find additional information on creating credential objects and best practices for managing service account keys by following the provided links to other documentation pages.\u003c/p\u003e\n"]]],[],null,[]]
