Authentication not working as expected when running GKE with a service account

Hello,

I have a GKE cluster configured to use a service account for the nodes. In addition I have created a separate service account with elevated permissions for the GCE Jenkins plugin.

I noticed that the GCE Jenkins plugin ignores the Service Account Credentials provided in the configuration section, and instead authenticates with the service account that the nodes are running as.

I get the following error: `Could not list regions in project `. Once given extra permissions to the first service account, everything works.

This is unexpected and very confusing. Hopefully it's an easy fix.

Thanks.

The issue identifies the GCE Jenkins plugin configuration, GKE node service account, and region-listing failure, but names no source file or test. Start by reproducing the authentication behavior and tracing how the plugin selects credentials; done means the configured service account is used instead of the node account and the reported error is resolved.

Written by the indexing model from the issue text.