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::datamigration_v1::DataMigrationServiceClient(
google::cloud::datamigration_v1::MakeDataMigrationServiceConnection(
options));
}
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 focusing on the \u003ccode\u003edatamigration\u003c/code\u003e service.\u003c/p\u003e\n"],["\u003cp\u003eThe most recent release candidate version available is 2.37.0-rc, while version 2.27.0 is displayed in the navigation header.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default Application Default Credentials by providing a \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, demonstrated in the example with loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe provided code example showcases how to explicitly load a service account key file using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e to authenticate with the \u003ccode\u003eDataMigrationServiceClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eRefer to the "Best practices for managing service account keys" and "Authentication Components" documentation for additional details on authentication and managing credentials.\u003c/p\u003e\n"]]],[],null,[]]
