Migrate from NGINX Ingress Controller to Istio with 0 downtime

Following the retirement of NGINX Ingress, Moss migrated the ingress layer of its Kubernetes clusters to Istio. As a fintech company with strict security and compliance requirements, the team carefully evaluated multiple solutions before selecting Istio. The top priority was ensuring zero downtime. By building a parallel Istio-based infrastructure, the team successfully migrated 60 microservices and 20 internal tools without service disruption, with thorough testing and monitoring to help ensure no requests were lost. The migration used Terraform, GCP, Helm, GKE, and Go.