AWS Controllers for Kubernetes vs Terragrunt

AWS Controllers for Kubernetes (ACK) lets Kubernetes users define AWS resources with Kubernetes custom resources. It periodically compares desired and actual AWS state and corrects drift. Documentation lists 74 service controllers, including S3, RDS, Lambda and DynamoDB. ACK supports declarative, version-controlled infrastructure alongside applications, across AWS accounts and regions. Read-only resources and read-only adoption support migration from other infrastructure-as-code tools. EKS users can install managed EKS Capabilities, where AWS handles controller installation and upgrades with automatic updates, auto-scaling and auto-tuning. Self-managed Helm installation runs on EKS, GKE, AKS, on-premises clusters and local environments, providing version and configuration control. AWS IAM authorizes controller access. Self-managed ACK costs nothing for Helm installation on Kubernetes 1.20+ on any Kubernetes cluster. EKS Capability pricing is hourly, with a base rate per enabled capability plus usage charges for each ACK resource managed.

Terragrunt is an open-source infrastructure-as-code orchestration tool for running Terraform and OpenTofu at scale. It organizes infrastructure into independently operated units and groups related units into stacks. Its Run Queue uses dependency relationships to order operations and allow safe concurrency where possible. Teams can define shared backend settings, provider configuration, module inputs, and environment conventions once, then inherit them across units. It supports AWS, Google Cloud, Microsoft Azure, and other Terraform- or OpenTofu-supported platforms, with self-hosted state management and the ability to import existing resources. The core tool is documented for Windows, macOS, and Linux. The Free Scale tier allows up to 25 infrastructure units, unlimited runs, and unlimited resources without RUM, with community support and no credit card required. Team costs $500 a month, reflecting a 17% annual contract discount, and includes 200 infrastructure units and standard support. Terragrunt Scale adds CI/CD pipelines, drift detection, and automated dependency updates, with GitHub and GitLab workflow support. Enterprise has custom pricing.