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 webpage provides documentation for the Eventarc C++ client library, specifically focusing on versions ranging from 2.11.0 to the latest release candidate, 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe content details how to override the default Application Default Credentials (ADC) when authenticating with Google Cloud Services by utilizing the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eAn example is given demonstrating how to load a service account key file and how to implement \u003ccode\u003eMakePublisherConnection\u003c/code\u003e function with the loaded key.\u003c/p\u003e\n"],["\u003cp\u003eThe page provides links to examples for other client classes such as \u003ccode\u003eeventarc_publishing_v1::PublisherClient\u003c/code\u003e and \u003ccode\u003eeventarc_v1::EventarcClient\u003c/code\u003e, showing how to implement the credentials.\u003c/p\u003e\n"],["\u003cp\u003eIt emphasizes the importance of consulting the "Best practices for managing service account keys" guide for more detailed information on managing authentication.\u003c/p\u003e\n"]]],[],null,["Version 2.29.0keyboard_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/2.29.0/eventarc_publishing_v1_1_1PublisherClient-service-account-snippet)\n- [`eventarc_v1::EventarcClient`](/cpp/docs/reference/eventarc/2.29.0/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."]]