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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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\u003eDataMigrationServiceClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release is version 2.37.0-rc, with multiple versions available, starting from 2.11.0, that link to documentation pertaining to overriding authentication for DataMigration.\u003c/p\u003e\n"],["\u003cp\u003eThe default authentication mechanism utilizes Application Default Credentials, but the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e allows you to use alternate means, like a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eAn example is given to help visualize how you would load a service account key file to provide new credentials.\u003c/p\u003e\n"],["\u003cp\u003eThe provided documentation includes links to best practices for managing service account keys and further information on Authentication Components.\u003c/p\u003e\n"]]],[],null,[]]
