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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 document details how to override default authentication credentials when using Google Cloud client libraries, which by default utilize Application Default Credentials.\u003c/p\u003e\n"],["\u003cp\u003eOverriding the default authentication can be accomplished by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, such as by loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe provided example uses \u003ccode\u003eEnvironmentsClient\u003c/code\u003e to show the implementation of overriding credentials, with links to other \u003ccode\u003e*Client\u003c/code\u003e class examples, \u003ccode\u003eImageVersionsClient\u003c/code\u003e included.\u003c/p\u003e\n"],["\u003cp\u003eVersion history for the composer, starting from \u003ccode\u003e2.37.0-rc\u003c/code\u003e to \u003ccode\u003e2.11.0\u003c/code\u003e, is available.\u003c/p\u003e\n"],["\u003cp\u003eFor further information, you can find more details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects by checking out the "Authentication Components" section.\u003c/p\u003e\n"]]],[],null,[]]
