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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 services, which typically use Application Default Credentials.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as demonstrated with an example loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe examples provided show how to load a service account key file and create an \u003ccode\u003eEnvironmentsClient\u003c/code\u003e with the overridden credentials, with additional links for the \u003ccode\u003eImageVersionsClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe document includes a comprehensive list of documentation versions, ranging from 2.11.0 to 2.37.0-rc, with the link to the latest release candidate version.\u003c/p\u003e\n"],["\u003cp\u003eFor further details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects, refer to the Authentication Components section that is linked at the bottom of the document.\u003c/p\u003e\n"]]],[],null,[]]
