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::migrationcenter_v1::MigrationCenterClient(
google::cloud::migrationcenter_v1::MakeMigrationCenterConnection(
options));
}
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThe latest version available is 2.37.0-rc, with numerous previous versions from 2.36.0 down to 2.13.0 also documented.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries generally authenticate using Application Default Credentials, but this can be overridden when needed.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default credentials by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, which enables the explicit loading of a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe provided code sample illustrates overriding authentication by loading a service account key file, offering a straightforward method for customization.\u003c/p\u003e\n"],["\u003cp\u003eFor comprehensive information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects, you can refer to the Authentication Components section.\u003c/p\u003e\n"]]],[],null,[]]
