Includes a Kubernetes CronJob which runs nightly, updating Istio to the latest daily release.
This CronJob should be installed in "istio-system":
kubectl -n istio-system apply -f cron-job.yaml
prom_scrape.py
is copied as a starter for querying Prometheus during the
update and reporting any errors that occur during the update. Traffic is assumed
to be ongoing during the update.