Unless otherwise configured, the client libraries useApplication Default Credentialsto 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 theUnifiedCredentialsOptionThe 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::eventarc_publishing_v1::PublisherClient(
google::cloud::eventarc_publishing_v1::MakePublisherConnection(
options));
}
Follow these links to find examples for other*Clientclasses:
[[["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 2025-09-04 UTC."],[[["\u003cp\u003eThis document provides information on overriding default authentication credentials when using Google Cloud client libraries, specifically focusing on the Eventarc service.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate for the Eventarc C++ client library is version 2.37.0-rc, with numerous previous versions listed, ranging down to version 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eAuthentication with Google Cloud services can be achieved by using Application Default Credentials, but overriding this is possible by employing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eService account key files can be explicitly loaded to override the default credentials, as demonstrated by the provided code example showing how to load a key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples for other \u003ccode\u003e*Client\u003c/code\u003e classes are available for \u003ccode\u003eeventarc_publishing_v1::PublisherClient\u003c/code\u003e and \u003ccode\u003eeventarc_v1::EventarcClient\u003c/code\u003e, showing how to use service accounts.\u003c/p\u003e\n"]]],[],null,["Version 2.13.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/eventarc/latest/eventarc-override-authentication)\n- [2.41.0](/cpp/docs/reference/eventarc/2.41.0/eventarc-override-authentication)\n- [2.40.0](/cpp/docs/reference/eventarc/2.40.0/eventarc-override-authentication)\n- [2.39.0](/cpp/docs/reference/eventarc/2.39.0/eventarc-override-authentication)\n- [2.38.0](/cpp/docs/reference/eventarc/2.38.0/eventarc-override-authentication)\n- [2.37.0](/cpp/docs/reference/eventarc/2.37.0/eventarc-override-authentication)\n- [2.36.0](/cpp/docs/reference/eventarc/2.36.0/eventarc-override-authentication)\n- [2.35.0](/cpp/docs/reference/eventarc/2.35.0/eventarc-override-authentication)\n- [2.34.0](/cpp/docs/reference/eventarc/2.34.0/eventarc-override-authentication)\n- [2.33.0](/cpp/docs/reference/eventarc/2.33.0/eventarc-override-authentication)\n- [2.32.0](/cpp/docs/reference/eventarc/2.32.0/eventarc-override-authentication)\n- [2.31.0](/cpp/docs/reference/eventarc/2.31.0/eventarc-override-authentication)\n- [2.30.0](/cpp/docs/reference/eventarc/2.30.0/eventarc-override-authentication)\n- [2.29.0](/cpp/docs/reference/eventarc/2.29.0/eventarc-override-authentication)\n- [2.28.0](/cpp/docs/reference/eventarc/2.28.0/eventarc-override-authentication)\n- [2.27.0](/cpp/docs/reference/eventarc/2.27.0/eventarc-override-authentication)\n- [2.26.0](/cpp/docs/reference/eventarc/2.26.0/eventarc-override-authentication)\n- [2.25.1](/cpp/docs/reference/eventarc/2.25.1/eventarc-override-authentication)\n- [2.24.0](/cpp/docs/reference/eventarc/2.24.0/eventarc-override-authentication)\n- [2.23.0](/cpp/docs/reference/eventarc/2.23.0/eventarc-override-authentication)\n- [2.22.1](/cpp/docs/reference/eventarc/2.22.1/eventarc-override-authentication)\n- [2.21.0](/cpp/docs/reference/eventarc/2.21.0/eventarc-override-authentication)\n- [2.20.0](/cpp/docs/reference/eventarc/2.20.0/eventarc-override-authentication)\n- [2.19.0](/cpp/docs/reference/eventarc/2.19.0/eventarc-override-authentication)\n- [2.18.0](/cpp/docs/reference/eventarc/2.18.0/eventarc-override-authentication)\n- [2.17.0](/cpp/docs/reference/eventarc/2.17.0/eventarc-override-authentication)\n- [2.16.0](/cpp/docs/reference/eventarc/2.16.0/eventarc-override-authentication)\n- [2.15.1](/cpp/docs/reference/eventarc/2.15.1/eventarc-override-authentication)\n- [2.14.0](/cpp/docs/reference/eventarc/2.14.0/eventarc-override-authentication)\n- [2.13.0](/cpp/docs/reference/eventarc/2.13.0/eventarc-override-authentication)\n- [2.12.0](/cpp/docs/reference/eventarc/2.12.0/eventarc-override-authentication)\n- [2.11.0](/cpp/docs/reference/eventarc/2.11.0/eventarc-override-authentication) \n\nHow to Override the Authentication Credentials\n==============================================\n\nUnless otherwise configured, the client libraries use [Application Default Credentials](https://cloud.google.com/docs/authentication#adc) 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](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1UnifiedCredentialsOption.html) The following example shows how to explicitly load a service account key file: \n\n [](std::string const& keyfile) {\n auto is = std::ifstream(keyfile);\n is.exceptions(std::ios::badbit); // Minimal error handling in examples\n auto contents = std::string(std::istreambuf_iterator\u003cchar\u003e(is.rdbuf()), {});\n auto options =\n google::cloud::Options{}.set\u003cgoogle::cloud::UnifiedCredentialsOption\u003e(\n google::cloud::MakeServiceAccountCredentials(contents));\n return google::cloud::eventarc_publishing_v1::PublisherClient(\n google::cloud::eventarc_publishing_v1::MakePublisherConnection(\n options));\n }\n\nFollow these links to find examples for other `*Client` classes:\n\n- [`eventarc_publishing_v1::PublisherClient`](/cpp/docs/reference/eventarc/2.13.0/eventarc_publishing_v1_1_1PublisherClient-service-account-snippet)\n- [`eventarc_v1::EventarcClient`](/cpp/docs/reference/eventarc/2.13.0/eventarc_v1_1_1EventarcClient-service-account-snippet)\n\nKeep in mind that we chose this as an example because it is relatively easy to understand. Consult the [Best practices for managing service account keys](https://cloud.google.com/iam/docs/best-practices-for-managing-service-account-keys) guide for more details.\n\n###### See Also\n\n[Authentication Components](https://cloud.google.com/cpp/docs/reference/common/latest/group__guac.html) - for more information on the factory functions to create [`google::cloud::Credentials`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1Credentials.html) objects."]]