Google Spanner - Execute a query using custom credentials

Question

Using C#, I am trying execute a query on Google Spanner db. I understand I can use the SpannerClient and all the current documentation explains how to execute a query quite simply, however these examples all assume default environment credentials.

I would like to execute a query against a given database but using custom credentials. So something like

var credentials = GoogleCredential.FromJson(jsonData);
SpannerClient client = new SpannerClient(connectionString, credentials)

var cmd = client.CreateSelectCommand("SELECT SingerId, AlbumId, AlbumTitle FROM Albums");

etc

I am currently unable to figure out how to do this?

Thanks

Answer 1

Currently this isn't as clean as we'd like it to be. You need to create a ChannelCredentials for the credentials, and provide that to the SpannerConnectionStringBuilder:

// First load the credentials, scope them, and convert to ChannelCredentials.
// You may want to move this to a separate method.
var googleCredential = GoogleCredential.FromJson(jsonData);
googleCredential = googleCredential.CreateScoped(SpannerClient.DefaultScopes);
// Use self-signed JWTs for service accounts.
// (This isn't strictly required, but reduces network usage.)
if (googleCredential.UnderlyingCredential is ServiceAccountCredential serviceCredential)
{
    googleCredential = GoogleCredential.FromServiceAccountCredential(
        serviceCredential.WithUseJwtAccessWithScopes(true));
}
// Note: this requires a using directive of "using Grpc.Auth;"
var channelCredentials = googleCredential.ToChannelCredentials();


// Now create a SpannerConnection with the SpannerCredentials
using var conn = new SpannerConnection(connectionString, credentials);
using var cmd = conn.CreateSelectCommand("SELECT ...");
...

We definitely hope to improve this - we have a tracking bug you might want to subscribe to so that you can simplify your code when it's fixed.