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::networkmanagement_v1::ReachabilityServiceClient(
google::cloud::networkmanagement_v1::MakeReachabilityServiceConnection(
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."],[[["The latest version available is 2.37.0-rc, with numerous other versions from 2.36.0 down to 2.11.0 also being accessible."],["Client libraries primarily use Application Default Credentials for authentication with Google Cloud Services, unless an alternative configuration is specified."],["Users can override the default authentication by providing the UnifiedCredentialsOption, as demonstrated in the example showing how to load a service account key file."],["The provided example is intended to be easy to understand, and users should refer to the best practices guide for managing service account keys for more detailed information."],["The Authentication Components link provides more information on the factory functions to create `google::cloud::Credentials` objects."]]],[]]
