err := retry.Until(func() bool {
							stc.Logf("sending call from %q to %q", deployName(localSrc), localDst.Config().Service)
							localSrc.CallOrFail(stc, opt)
							reqs, err := prom.QuerySum(localSrc.Config().Cluster, query)
							if err != nil {
								stc.Logf("could not query for traffic from %q to %q: %v", deployName(localSrc), localDst.Config().Service, err)
								return false
							}