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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 webpage provides documentation for various versions of the Migration Center, ranging from version 2.13.0 to the latest release candidate, 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe primary content demonstrates how to override the default authentication credentials used by the client libraries, utilizing \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eBy loading a service account key file, users can explicitly define the credentials used for Google Cloud service authentication, as demonstrated in the provided example code snippet.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation highlights the importance of managing service account keys securely and refers users to best practices for doing so.\u003c/p\u003e\n"],["\u003cp\u003eUsers can find more details on the creation of \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects in the linked Authentication Components documentation.\u003c/p\u003e\n"]]],[],null,[]]
