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#service-mesh

2 stories

DevOps & CI/CD Bug Report

Istio 503 "upstream connect error" in the first seconds of every pod: app started before the proxy

Sofia Andersson · Oct 14, 2026 · 7 min read

After adding Istio to our EKS cluster, every rollout produced a burst of failures: startup jobs could not reach the database and calls returned 503 upstream connect error. The application started before its Envoy sidecar was ready. How we proved it and fixed it with native sidecars and holdApplicationUntilProxyStarts.

Networking & DNS Bug Report

Scaled to 10 pods, one pod at 100% CPU: gRPC connections pinned behind a ClusterIP Service

Priya Raghavan · Sep 29, 2026 · 7 min read

Our pricing service scaled from 3 to 10 replicas under load, but one pod stayed at 100% CPU while others idled. gRPC uses long-lived HTTP/2 connections, and a ClusterIP Service balances connections, not requests. How we found it and fixed it with client-side load balancing, a headless Service and MaxConnectionAge.