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::channel_v1::CloudChannelServiceClient(
google::cloud::channel_v1::MakeCloudChannelServiceConnection(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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThe latest version available is 2.37.0-rc, with numerous other versions, from 2.36.0 down to 2.11.0, also accessible via the provided links.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries typically use Application Default Credentials for Google Cloud Services, but this can be overridden if required.\u003c/p\u003e\n"],["\u003cp\u003eOverriding default credentials can be done using \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, and an example is provided that loads a service account key file for authentication.\u003c/p\u003e\n"],["\u003cp\u003eExamples for \u003ccode\u003echannel_v1::CloudChannelServiceClient\u003c/code\u003e and \u003ccode\u003echannel_v1::CloudChannelReportsServiceClient\u003c/code\u003e are available to demonstrate how to override default credentials.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ca href=\"https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys\"\u003eBest practices for managing service account keys\u003c/a\u003e guide is linked for detailed information on service account key management.\u003c/p\u003e\n"]]],[],null,[]]
