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::dataproc_v1::AutoscalingPolicyServiceClient(
google::cloud::dataproc_v1::MakeAutoscalingPolicyServiceConnection(
options));
}
Follow these links to find examples for other *Client classes:
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-09 UTC."],[[["The latest release candidate version is 2.37.0-rc, and a list of previous versions from 2.36.0 down to 2.11.0 are available with corresponding links."],["Client libraries typically use Application Default Credentials for authentication with Google Cloud Services, but these can be overridden."],["You can override the default credentials by providing the UnifiedCredentialsOption, such as explicitly loading a service account key file, as shown in the provided example code."],["Examples of how to override authentication for specific client classes like `AutoscalingPolicyServiceClient`, `BatchControllerClient`, and others are provided."],["It is recommended to consult the \"Best practices for managing service account keys\" guide for more detailed information on managing authentication."]]],[]]
