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"]],[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 various versions of the Migration Center, ranging from 2.13.0 to the latest release candidate 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries use Application Default Credentials for authentication with Google Cloud Services unless other configurations are applied.\u003c/p\u003e\n"],["\u003cp\u003eYou can override default credentials by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, which is shown through the example of loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eIt's recommended to review the "Best practices for managing service account keys" guide for detailed information about service account key management.\u003c/p\u003e\n"],["\u003cp\u003eThe "Authentication Components" link provides additional information on how to create \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects using factory functions.\u003c/p\u003e\n"]]],[],null,[]]
