AWS Terraform Patterns#

AWS is the most common Terraform target and the most complex. It has more services, more configuration options, and more subtle gotchas than Azure or GCP. This article covers the AWS-specific patterns that agents need to write correct, secure Terraform — with emphasis on the mistakes that cause real production issues.

IAM: The Foundation of Everything#

Every AWS resource that does anything needs IAM permissions. The two patterns agents must know: service roles (letting AWS services act on your behalf) and IRSA (letting Kubernetes pods assume IAM roles).

Cloud Behavioral Divergence Guide#

Running the “same” workload on AWS, Azure, and GCP does not produce the same behavior. The Kubernetes API is portable, application containers are portable, and SQL queries are portable. Everything else – identity, networking, storage, load balancing, DNS, and managed service behavior – diverges in ways that matter for production reliability.

This guide documents the specific divergence points with practical examples. Use it when translating infrastructure from one cloud to another, when debugging behavior that differs between environments, or when assessing migration risk.

EKS IAM and Security#

EKS bridges two identity systems: AWS IAM and Kubernetes RBAC. Understanding how they connect is essential for both granting pods access to AWS services and controlling who can access the cluster.

IAM Roles for Service Accounts (IRSA)#

IRSA lets Kubernetes pods assume IAM roles without using node-level credentials. Each pod gets exactly the AWS permissions it needs, not the broad permissions attached to the node role.