Terraform Modular EKS + Istio — Part 2

IAM Module (IRSA, OIDC, and Why This Controls Everything) In the previous part, we built the VPC. Now we move to something that causes the most confusion in EKS setups: 👉 IAM This is not just “permissions”. This module controls: how EKS works how nodes behave how pods access AWS services If this is wrong: ALB won’t work CSI drivers fail Pods can’t access AWS Debugging becomes painful 📂 Module Files modules/iam/ ├── main.tf ├── variables.tf └── outputs.tf 📄 variables.tf variable "cluster_name" { description = "Name of the EKS cluster" type = string } variable "oidc_provider_arn" { description = "ARN of the OIDC provider" type = string } variable "oidc_provider" { description = "OIDC provider URL" type = string } 🧠 What these inputs mean cluster_name → used to name roles oidc_provider_arn → comes from EKS module oidc_provider → used for IRSA condition matching 👉 Important: This module depends on EKS Because OIDC is created inside the EKS module. 📄 main.tf (Core IAM Logic) 1. EKS Cl