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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 client library, ranging from version 2.11.0 up to the release candidate 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe content demonstrates how to override default authentication credentials using a service account key file by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e within \u003ccode\u003egoogle::cloud::Options\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe default authentication for the client libraries use Application Default Credentials, which can be overridden if the need to do so arises.\u003c/p\u003e\n"],["\u003cp\u003eThe example uses \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e to create the credentials from a service account key file that must be loaded first, and the documentation recommends reading the best practices for managing service account keys for more details.\u003c/p\u003e\n"]]],[],null,[]]
