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"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-03-14 UTC."],[[["This page details how to override the default authentication credentials used by client libraries when interacting with Google Cloud Services."],["The latest version documented is 2.37.0-rc, with a range of versions down to 2.13.0 available for reference."],["Overriding default credentials can be accomplished using `UnifiedCredentialsOption`, as demonstrated by an example of loading a service account key file."],["The default setting of client libraries use [Application Default Credentials](https://cloud.google.com/docs/authentication#adc) for authentication."],["For more on Authentication, you can refer to [Authentication Components](https://cloud.google.com/cpp/docs/reference/common/latest/group__guac.html), and for more on managing service account keys, refer to [Best practices for managing service account keys](https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys)."]]],[]]
