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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 vmmigration component, ranging from version 2.11.0 up to the release candidate 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe documentation includes a guide on how to override the default authentication credentials, which are typically Application Default Credentials, for the client libraries when connecting to Google Cloud Services.\u003c/p\u003e\n"],["\u003cp\u003eOverriding default authentication can be accomplished by utilizing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and loading a service account key file, as demonstrated in the provided code example.\u003c/p\u003e\n"],["\u003cp\u003eThe example highlights a simple method for loading a service account key file and is intended for demonstration purposes; users are encouraged to review the "Best practices for managing service account keys" for production environments.\u003c/p\u003e\n"],["\u003cp\u003eAdditional information regarding the creation of \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects can be found in the "Authentication Components" documentation.\u003c/p\u003e\n"]]],[],null,[]]
