The "Day 2" Problem
A freshly created EKS cluster is not ready to run production workloads. It needs a set of operational components — sometimes called "Day 2" software — to function correctly:
| Add-on | Purpose |
|---|---|
vpc-cni |
Assigns VPC IPs to pods |
coredns |
Resolves Kubernetes service names (e.g., my-service.default.svc.cluster.local) |
kube-proxy |
Maintains iptables/ipvs rules for Service routing on each node |
aws-ebs-csi-driver |
Allows pods to mount EBS volumes as persistent storage |
aws-efs-csi-driver |
Allows pods to mount EFS (shared filesystem) volumes |
The Old Way: Helm Charts
Before managed add-ons, teams installed these components using Helm charts. This created several problems:
- You had to track which chart version was compatible with which Kubernetes version.
- Upgrades required manual testing and coordination.
- Drift was common — different clusters in the same organization ran different versions.
Managed Add-ons: The EKS Way
EKS Managed Add-ons let you install, configure, and upgrade these components through the AWS Console, CLI, or IaC tools like Terraform. Installing one is a single call naming the cluster, the add-on, a version, and — for add-ons that need AWS permissions like the EBS CSI driver — the IRSA role to attach.
Key benefits:
- Version compatibility: AWS publishes which add-on versions work with which Kubernetes versions. You cannot accidentally install an incompatible version.
- Conflict detection: If you have a self-managed version of the same component already installed, EKS warns you before overwriting it.
- Simplified upgrades: When you upgrade your cluster's Kubernetes version, EKS can automatically upgrade add-ons to compatible versions.
Conflict resolution policy: When updating a managed add-on, you can set --resolve-conflicts OVERWRITE to let EKS overwrite any custom configuration you've applied to the add-on's Kubernetes resources. Use PRESERVE if you've made custom changes you want to keep — but be aware that this may cause the update to fail if there are incompatibilities.