What should I add to an EKS cluster when moving from Elastic Beanstalk?

I'd start with the VPC CNI rather than switch just because other options exist. It can enforce Kubernetes NetworkPolicy when that feature is enabled and the setup meets its requirements. Check the policies you need against the supported behavior before deciding whether Cilium or Calico would give you something useful.

Also plan your pod IP space early, especially in a shared VPC. A separate pod CIDR or subnet is worth considering before address availability becomes a constraint.

Where's the monitoring stack? Cluster CPU and pod metrics are a start, but you'll also want application metrics, logs and traces. Prometheus, Grafana, Loki and Tempo are one possible combination.

For application telemetry, look at the OpenTelemetry Collector and Operator. The operator can help manage collectors and supports annotation-based auto-instrumentation for supported applications. Check language and runtime support rather than assuming every app will be covered.

Sort out the AWS integration pieces early. The AWS Load Balancer Controller can manage ALBs and NLBs, and ExternalDNS can automate Route 53 records. Decide how workloads will get AWS permissions too, whether that's IRSA or EKS Pod Identity.

For TLS, think through both public and internal certificates. That might involve AWS Certificate Manager for load balancers and cert-manager for certificates used inside the cluster.

Consider NodeLocal DNSCache if DNS latency or load on CoreDNS becomes a concern. It adds another component to run, so I'd check your DNS traffic and performance before treating it as mandatory.