Is there a way to use gcloud auth credentials for BigQuery connections?

[nkamat-im]

I'm unable to query BQ from dbx because I primarily use gcloud auth to connect to GCP services. I don't see a way to use that to connect to BQ via dbx.

[TOMOYAKATO-292]

Yes — you can use your gcloud credentials. It isn't surfaced as a named auth option in the connection form, but you can pass it through the URL params field.

Why this works

DBX reaches BigQuery through a JDBC agent rather than a native driver. BigQueryAgent.driverClass() returns com.simba.googlebigquery.jdbc.Driver, and buildUrl() in agents/drivers/bigquery/src/main/java/com/dbx/agent/bigquery/BigQueryAgent.java (lines 178-182 on main) does this:

static String buildUrl(ConnectParams params) {
    String url = "jdbc:bigquery://" + params.getHost() + ":" + params.getPort()
               + ";ProjectId=" + params.getDatabase();
    String extraParams = trimSemicolons(params.getUrl_params());
    return extraParams.isBlank() ? url : url + ";" + extraParams;
}

Anything in url_params is appended verbatim to the JDBC URL, so every Simba driver property is reachable. The Simba driver selects its auth method via OAuthType, and OAuthType=3 means Application Default Credentials — exactly what gcloud auth application-default login writes to disk.

Steps

1. Run gcloud auth application-default login.
2. In the DBX BigQuery connection:
   • Host: https://www.googleapis.com/bigquery/v2 (the default)
   • Port: 443 (the default)
   • Database: your GCP project id — this becomes ProjectId
   • URL params: OAuthType=3
3. Connect.

The resulting JDBC URL is:

jdbc:bigquery://https://www.googleapis.com/bigquery/v2:443;ProjectId=my-project;OAuthType=3

One thing to check first

BigQuery is an external-driver agent in DBX (Agent-External-Driver: true / external_driver_required: true, see agents/docs/release-checklist.md), so the Simba BigQuery JDBC jar is not bundled — you need to supply it yourself before the agent will start.

If you ever run DBX on GCE, GKE or Cloud Run, OAuthType=3 also picks up the attached service account with no key file at all.

One caveat: I haven't run this myself — the above comes from reading the agent source and the Simba documentation, so please confirm it on your setup.

References:

• Using Application Default Credentials — Simba Google BigQuery JDBC Connector
• Configuring Authentication — Simba Google BigQuery JDBC Connector