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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically for the Composer service.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version covered is 2.37.0-rc, and the page lists links to documentation for various versions ranging from 2.37.0-rc down to 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eOverriding authentication is done via \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, using an example of how to load a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for other client classes such as \u003ccode\u003eEnvironmentsClient\u003c/code\u003e and \u003ccode\u003eImageVersionsClient\u003c/code\u003e are provided, with links to each.\u003c/p\u003e\n"],["\u003cp\u003eIt is recommended to consult the "Best practices for managing service account keys" guide for further information on managing service account keys.\u003c/p\u003e\n"]]],[],null,[]]
