code: def fetch_cluster_credentials(cls, db_user, db_name, cluster_id,
                                    duration_s):
          
          boto_client = boto3.client('redshift')
  
          try:
              return boto_client.get_cluster_credentials(
                  DbUser=db_user,
                  DbName=db_name,
                  ClusterIdentifier=cluster_id,
                  DurationSeconds=duration_s,
                  AutoCreate=False)
  
          except boto_client.exceptions.ClientError as e:
              raise dbt.exceptions.FailedToConnectException(
                  "Unable to get temporary Redshift cluster credentials: {}"
                  .format(e))
docs: Fetches temporary login credentials from AWS. The specified user
          must already exist in the database, or else an error will occur