Simplify Your Kubernetes Platform with Terragrunt: A Comprehensive Walkthrough

Introduction

Managing a cloud-native platform at scale can be challenging, especially when dealing with multiple tools, services, and dependencies. Terragrunt offers a consistent and streamlined approach to deploying and maintaining complex infrastructures.

This article will explore leveraging Kubernetes Platform Terragrunt Configuration to set up an end-to-end Kubernetes ecosystem with core components, networking, observability, and more.

The Big Picture: Architecture

Below is a high-level architecture that illustrates the essential modules and their relationships.

Key Highlights:

• Core Platform: Manages vital capabilities like node provisioning (Karpenter), DNS integration (External DNS), certificate management (Cert Manager), and secret management (External Secrets).
• Networking & Service Mesh: Tightly integrates Istio, Kong Gateway, and Jaeger for routing and distributed tracing.
• Observability: Implements Loki for logs and Kubecost for cost insights.
• Platform Tools: Offers GitOps (ArgoCD), Terraform collaboration (Atlantis), workflow management (Airflow), and advanced secret management (Vault).

Why Terragrunt?

Terragrunt extends Terraform’s functionality by introducing:

1. DRY (Don’t Repeat Yourself): Centralize standard configurations (like common.hcl) and reduce duplication across multiple modules.
2. Automated Dependencies: Terragrunt’s dependency management ensures proper deployment order.
3. Consistent Environment Management: Standardize your environment configurations (like platform_vars.yaml) for dev, stage, and production.

Repository Structure

.
├── core-platform/          # Core platform components
│   ├── cert-manager        # Certificate management
│   ├── external-dns        # DNS automation
│   ├── external-secrets    # Secrets management
│   └── karpenter           # Kubernetes node provisioning
├── service-mesh/           # Service mesh components
│   ├── istio               # Service mesh control plane
│   ├── jeager              # Distributed tracing
│   └── kong-gw             # API gateway
├── observability/          # Monitoring and observability
│   ├── kubecost            # Cost monitoring
│   └── loki-stack          # Log aggregation
├── platform-tools/         # Platform utilities
│   ├── airflow             # Workflow automation
│   ├── argocd              # GitOps deployment
│   ├── atlantis            # Terraform automation
│   └── vault               # Secrets management
└── ci-cd-templates/        # Reusable CI/CD workflows

This modular layout allows teams to maintain, iterate, and scale independently on each platform component.

Prerequisites

To get started, ensure you have the following tools properly installed and configured:

• Terragrunt >= v0.60.0
• Terraform >= v1.5.0
• AWS CLI configured
• kubectl configured
• Helm v3.x

Getting Started

1. Configure Common Settings

In common.hcl, you’ll find shared values, like the EKS cluster name and AWS region:

locals {
  platform_vars    = yamldecode(file(("platform_vars.yaml")))
  eks_cluster_name = local.platform_vars.common.eks_cluster_name
  environment      = get_env("ENV", "dev")
  aws_region       = local.platform_vars.common.aws_region
  tags             = local.platform_vars.common.common_tags
}

2. Define Platform Variables

Inside platform_vars.yaml, you set environment-specific details like domain name, AWS region, and tagging:

aws_region:       "us-east-2"
eks_cluster_name: "dev-eks-cluster"
environment:      "dev"
domain_name:      "cloudon.work"
common_tags:
    Environment:  "dev"
    Owner:        "cloudon"
    ManagedBy:    "Terragrunt"
    Team:         "platform"
    ClusterName:  "dev-eks-cluster"
...

3. Deployment Order

1. Core Platform

terragrunt run-all apply --terragrunt-working-dir core-platform

2. Service Mesh & Networking

terragrunt run-all apply --terragrunt-working-dir service-mesh

3. Observability

terragrunt run-all apply --terragrunt-working-dir observability

4. Platform Tools

terragrunt run-all apply --terragrunt-working-dir platform-tools

Day 2 Operations

Updating a Component

cd component-name
terragrunt apply

This allows you to quickly apply changes for a single module without affecting the rest of the platform.

Backing Up Terraform State

terragrunt state pull > backup.tfstate

Always keep regular state backups to ensure a smooth recovery if something goes wrong.

Security Considerations

• IRSA: Ensure each Kubernetes service account has the minimum privileges needed.
• Network Policies: Use Istio and Kong to manage traffic flow and encrypt communication.
• Vault & External Secrets: Keep sensitive data out of your Git repository and manage secrets securely.

Monitoring & Observability

Leverage best-in-class tools right out of the box:

• Loki Stack for log aggregation
• Jaeger for distributed tracing
• Kubecost for granular cost monitoring
• Grafana dashboards for custom insights

CI/CD Integration

The repository’s ci-cd-templates folder includes reusable workflows for:

• Docker Builds
• Terragrunt Plan/Apply
• Environment Variable Management

Additionally, you’ll find test coverage action templates for multiple languages like Java, .NET, Node.js, and Python.

Ready to Dive In?

This guide scratches what’s possible with a well-structured Terragrunt + Kubernetes setup.

For detailed configurations, advanced workflows, and troubleshooting tips, check out the k8s-platform-tools GitHub repository.

Contributing

We welcome contributions! Fork the repo, make changes, and open a Pull Request to get your updates reviewed and merged.

License

This project is available under the MIT License. Details can be found in the repository’s LICENSE file.

Final Thoughts

Combining Kubernetes with Terragrunt best practices provides a robust foundation for scalable, reliable, and secure cloud-native platforms. Whether you’re optimizing workloads, orchestrating microservices, or just exploring GitOps, this configuration offers a head start on the journey.

Stay tuned for updates, and feel free to open issues or submit PRs in the GitHub repo. Happy deploying!