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::composer_v1::EnvironmentsClient(
google::cloud::composer_v1::MakeEnvironmentsConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 details how to override the default authentication credentials for Google Cloud client libraries, specifically using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe most recent release candidate is version 2.37.0-rc, with the most recent stable release being 2.36.0, and this page also displays a history of releases down to version 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eAn example is provided demonstrating how to load a service account key file using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e to override the default credentials.\u003c/p\u003e\n"],["\u003cp\u003eLinks are available for examples related to \u003ccode\u003ecomposer_v1::EnvironmentsClient\u003c/code\u003e and \u003ccode\u003ecomposer_v1::ImageVersionsClient\u003c/code\u003e for overriding the default authentication in other clients.\u003c/p\u003e\n"],["\u003cp\u003eThis page links to the "Best practices for managing service account keys" guide and the "Authentication Components" documentation for further information on authentication and managing service account keys.\u003c/p\u003e\n"]]],[],null,[]]
