Amazon ECS Service Connect adds zone-aware routing

Amazon ECS Service Connect now routes traffic to healthy endpoints in the same Availability Zone as the client task by default. This feature reduces cross-zone data transfer costs and minimizes network latency. It is enabled by default for new and existing services, with existing services requiring a one-time redeployment to activate.

The Envoy sidecar proxy in ECS Service Connect discovers endpoints, prioritizes local AZ traffic, and routes based on residual capacity. It falls back to other AZs if local endpoints are unavailable and rebalances dynamically as endpoints scale.

Zone-aware routing offers reduced data transfer costs by prioritizing intra-AZ communication, lower network latency through fewer AZ traversals, and preserved high availability via automatic spillover to other zones. No application code changes are needed as the Envoy proxy handles the routing.

The post provides a detailed walkthrough demonstrating how to set up a multi-AZ ECS cluster, deploy services with Service Connect, and verify zone-aware routing. It includes steps for creating security groups, ECS clusters, launch templates, load balancers, task definitions, and services, along with verification and failover testing.