Istio and Envoy is used by
Istio helps you abstract the network layer from your business logic. You can monitor and manage your traffic to various multi-cluster and multi-cloud microservices from a single place.
Istio provides all the metrics (latency, traffic, errors, and saturation) to understand the performance of your services across clusters. Based on the under-utilized resources, you can automatically decrease the number of pods for resources to cut down cloud costs.
The price of traffic going outside the cloud VM (or egress traffic) can be costly (check out the GCP and AWS price). Istio can be used to monitor the egress traffic and calculate the cost you incur for each microservice for external communication, so that you can optimize them further and reduce cloud bills.
Rollout strategies like Blue-green can be simple yet costly, as they require two replicas to rollout a service each time. Hence it is recommended to deploy services using canary. Istio service mesh helps in traffic splitting which can be a very cost-effective solution for rolling out new features.