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::memcache_v1::CloudMemcacheClient(
google::cloud::memcache_v1::MakeCloudMemcacheConnection(options));
}
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 documented.\u003c/p\u003e\n"],["\u003cp\u003eClient libraries use Application Default Credentials (ADC) for authentication with Google Cloud Services unless overridden.\u003c/p\u003e\n"],["\u003cp\u003eYou can override default credentials by using the \u003ccode\u003eUnifiedCredentialsOption\u003c/code\u003e, for example by providing the content of a service account key file.\u003c/p\u003e\n"],["\u003cp\u003eThe provided example shows a simple way to load a service account key file to override the authentication, but users should also refer to best practices for managing service account keys.\u003c/p\u003e\n"],["\u003cp\u003eMore information about creating \u003ccode\u003egoogle::cloud::Credentials\u003c/code\u003e objects can be found in the Authentication Components section of the documentation.\u003c/p\u003e\n"]]],[],null,[]]
