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::channel_v1::CloudChannelServiceClient(
google::cloud::channel_v1::MakeCloudChannelServiceConnection(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 page provides documentation for overriding default authentication credentials when using Google Cloud client libraries, specifically focusing on versions of the Cloud Channel API.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version documented is 2.37.0-rc, while a range of prior versions, down to 2.11.0, are also available for reference regarding the Cloud Channel API.\u003c/p\u003e\n"],["\u003cp\u003eThe example demonstrates overriding credentials using a service account key file via the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e with \u003ccode\u003eMakeServiceAccountCredentials\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eLinks are provided for examples of how to override authentication for the \u003ccode\u003eCloudChannelServiceClient\u003c/code\u003e and \u003ccode\u003eCloudChannelReportsServiceClient\u003c/code\u003e classes, both within version 2.27.0.\u003c/p\u003e\n"],["\u003cp\u003eThe page references best practices and further details for managing service account keys and authentication components, in dedicated pages.\u003c/p\u003e\n"]]],[],null,["Version 2.27.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/channel/latest/channel-override-authentication)\n- [2.41.0](/cpp/docs/reference/channel/2.41.0/channel-override-authentication)\n- [2.40.0](/cpp/docs/reference/channel/2.40.0/channel-override-authentication)\n- [2.39.0](/cpp/docs/reference/channel/2.39.0/channel-override-authentication)\n- [2.38.0](/cpp/docs/reference/channel/2.38.0/channel-override-authentication)\n- [2.37.0](/cpp/docs/reference/channel/2.37.0/channel-override-authentication)\n- [2.36.0](/cpp/docs/reference/channel/2.36.0/channel-override-authentication)\n- [2.35.0](/cpp/docs/reference/channel/2.35.0/channel-override-authentication)\n- [2.34.0](/cpp/docs/reference/channel/2.34.0/channel-override-authentication)\n- [2.33.0](/cpp/docs/reference/channel/2.33.0/channel-override-authentication)\n- [2.32.0](/cpp/docs/reference/channel/2.32.0/channel-override-authentication)\n- [2.31.0](/cpp/docs/reference/channel/2.31.0/channel-override-authentication)\n- [2.30.0](/cpp/docs/reference/channel/2.30.0/channel-override-authentication)\n- [2.29.0](/cpp/docs/reference/channel/2.29.0/channel-override-authentication)\n- [2.28.0](/cpp/docs/reference/channel/2.28.0/channel-override-authentication)\n- [2.27.0](/cpp/docs/reference/channel/2.27.0/channel-override-authentication)\n- [2.26.0](/cpp/docs/reference/channel/2.26.0/channel-override-authentication)\n- [2.25.1](/cpp/docs/reference/channel/2.25.1/channel-override-authentication)\n- [2.24.0](/cpp/docs/reference/channel/2.24.0/channel-override-authentication)\n- [2.23.0](/cpp/docs/reference/channel/2.23.0/channel-override-authentication)\n- [2.22.1](/cpp/docs/reference/channel/2.22.1/channel-override-authentication)\n- [2.21.0](/cpp/docs/reference/channel/2.21.0/channel-override-authentication)\n- [2.20.0](/cpp/docs/reference/channel/2.20.0/channel-override-authentication)\n- [2.19.0](/cpp/docs/reference/channel/2.19.0/channel-override-authentication)\n- [2.18.0](/cpp/docs/reference/channel/2.18.0/channel-override-authentication)\n- [2.17.0](/cpp/docs/reference/channel/2.17.0/channel-override-authentication)\n- [2.16.0](/cpp/docs/reference/channel/2.16.0/channel-override-authentication)\n- [2.15.1](/cpp/docs/reference/channel/2.15.1/channel-override-authentication)\n- [2.14.0](/cpp/docs/reference/channel/2.14.0/channel-override-authentication)\n- [2.13.0](/cpp/docs/reference/channel/2.13.0/channel-override-authentication)\n- [2.12.0](/cpp/docs/reference/channel/2.12.0/channel-override-authentication)\n- [2.11.0](/cpp/docs/reference/channel/2.11.0/channel-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::channel_v1::CloudChannelServiceClient(\n google::cloud::channel_v1::MakeCloudChannelServiceConnection(options));\n }\n\nFollow these links to find examples for other `*Client` classes:\n\n- [`channel_v1::CloudChannelServiceClient`](/cpp/docs/reference/channel/2.27.0/channel_v1_1_1CloudChannelServiceClient-service-account-snippet)\n- [`channel_v1::CloudChannelReportsServiceClient`](/cpp/docs/reference/channel/2.27.0/channel_v1_1_1CloudChannelReportsServiceClient-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."]]