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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 version 2.13.0 up to the latest release candidate 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe content explains how to override the default authentication credentials used by the client libraries for Google Cloud Services, which typically utilize Application Default Credentials.\u003c/p\u003e\n"],["\u003cp\u003eOverriding authentication can be accomplished using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, as demonstrated by the example of loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eIt is recommended to refer to the "Best practices for managing service account keys" guide for additional information on securely managing service account keys.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation also directs users to the "Authentication Components" section for further details on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
