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::contentwarehouse_v1::DocumentServiceClient(
google::cloud::contentwarehouse_v1::MakeDocumentServiceConnection(
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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, starting at 2.36.0 and going all the way to 2.12.0, available for access.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries typically use Application Default Credentials for authentication, but this can be overridden when required for certain applications.\u003c/p\u003e\n"],["\u003cp\u003eYou can override the default authentication by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e and providing credentials, such as explicitly loading a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eExamples of overriding authentication credentials are provided for multiple \u003ccode\u003e*Client\u003c/code\u003e classes, including \u003ccode\u003eDocumentServiceClient\u003c/code\u003e, \u003ccode\u003eDocumentLinkServiceClient\u003c/code\u003e, \u003ccode\u003eDocumentSchemaServiceClient\u003c/code\u003e, \u003ccode\u003eRuleSetServiceClient\u003c/code\u003e, and \u003ccode\u003eSynonymSetServiceClient\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe guide suggests consulting the "Best practices for managing service account keys" for more details, and offers a link to "Authentication Components" for further information on creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects.\u003c/p\u003e\n"]]],[],null,[]]
