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::vmmigration_v1::VmMigrationClient(
google::cloud::vmmigration_v1::MakeVmMigrationConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 \u003ccode\u003evmmigration-override-authentication\u003c/code\u003e feature, ranging from version 2.11.0 up to the latest release candidate, 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe client libraries typically use Application Default Credentials for Google Cloud Services authentication, but this default behavior can be overridden if needed.\u003c/p\u003e\n"],["\u003cp\u003eUsers can override default credentials by providing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, with an example showing how to explicitly load a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eFor more details on credential management, refer to the "Best practices for managing service account keys" guide, as the example provided is only for demonstration purposes.\u003c/p\u003e\n"],["\u003cp\u003eAdditional information regarding the factory functions that can create google cloud credentials can be found at the "Authentication Components" section.\u003c/p\u003e\n"]]],[],null,[]]
