namespace spanner = ::google::cloud::spanner;
[](std::string const& project_id, std::string const& instance_id,
std::string const& database_id, std::string const& keyfile) {
auto is = std::ifstream(keyfile);
is.exceptions(std::ios::badbit);
auto contents = std::string(std::istreambuf_iterator<char>(is.rdbuf()), {});
auto options =
google::cloud::Options{}.set<google::cloud::UnifiedCredentialsOption>(
google::cloud::MakeServiceAccountCredentials(contents));
return spanner::Client(spanner::MakeConnection(
spanner::Database(project_id, instance_id, database_id), options));
}
Keep 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] guide for more details.
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-09 UTC."],[[["This webpage provides documentation and examples for various versions of the Spanner C++ client library, ranging from version 2.11.0 up to the latest release candidate 2.37.0-rc."],["The main content focuses on how to override the default authentication configuration using `google::cloud::UnifiedCredentialsOption` and provides an example of loading a service account key file."],["The documentation highlights best practices for managing service account keys, suggesting that the provided example is for illustrative purposes and users should consult the best practices guide."],["Links to additional examples for `DatabaseAdminClient` and `InstanceAdminClient` classes are provided, demonstrating authentication with a service account for these clients."],["A comprehensive list of previous versions with links to their respective documentation are available, such as version 2.36.0, 2.35.0 and so on."]]],[]]