Deploying an App with AWS EKS, Terraform & ArgoCD

Introduction

In modern DevOps workflows, Infrastructure as Code (IaC) and GitOps practices streamline software delivery. AWS EKS (Elastic Kubernetes Service) provides a managed Kubernetes cluster, while Terraform automates infrastructure provisioning. ArgoCD enables declarative, continuous delivery using Git repositories.

In this guide, we’ll:

✅ Provision an EKS cluster with Terraform✅ Containerize a sample application using Docker✅ Push the image to Amazon ECR (Elastic Container Registry)✅ Deploy the app to Kubernetes using ArgoCD & GitLab CI/CD✅ Implement GitOps for automatic deployments

🚀 Architecture Overview

The workflow consists of the following steps:

1️⃣ Terraform provisions AWS infrastructure (VPC, EKS, IAM roles, security groups)2️⃣ Docker builds & pushes a containerized app to AWS ECR3️⃣ Kubernetes manifests are stored in GitLab and deployed via ArgoCD4️⃣ GitLab CI/CD automates testing and deployment

1️⃣ Provisioning AWS EKS with Terraform

Step 1: Install Prerequisites

Ensure you have the following installed:

Terraform (>=1.5.0)
AWS CLI (aws configure)
Kubectl (eksctl install)
Helm (helm install)
ArgoCD CLI (argocd)

Step 2: Create Terraform Configuration for EKS

main.tf - Define the EKS cluster:

provider "aws" {
  region = "us-east-1"
}

resource "aws_eks_cluster" "my_eks" {
  name     = "my-cluster"
  role_arn = aws_iam_role.eks_cluster_role.arn
  vpc_config {
    subnet_ids = [aws_subnet.public_1.id, aws_subnet.public_2.id]
  }
}

Apply Terraform Configuration:

terraform init
terraform apply -auto-approve

Verify the cluster:

aws eks --region us-east-1 update-kubeconfig --name my-cluster
kubectl get nodes

2️⃣ Build and Push Docker Image to Amazon ECR

aws ecr create-repository --repository-name my-app
aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin <account_id>.dkr.ecr.us-east-1.amazonaws.com

docker build -t my-app .
docker tag my-app:latest <account_id>.dkr.ecr.us-east-1.amazonaws.com/my-app:latest
docker push <account_id>.dkr.ecr.us-east-1.amazonaws.com/my-app:latest

3️⃣ Deploying to Kubernetes with ArgoCD

Step 1: Install ArgoCD in EKS

kubectl create namespace argocd
kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

Step 2: Configure ArgoCD

Expose ArgoCD server:

kubectl port-forward svc/argocd-server -n argocd 8080:443

argocd login localhost:8080 --username admin --password <initial-password>

Step 3: Deploy Application with ArgoCD

application.yaml - Define ArgoCD application:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: my-app
  namespace: argocd
spec:
  destination:
    namespace: default
    server: https://kubernetes.default.svc
  source:
    repoURL: "https://gitlab.com/my-repo.git"
    targetRevision: main
    path: manifests/
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

Apply the application:

kubectl apply -f application.yaml

4️⃣ Automating with GitLab CI/CD

.gitlab-ci.yml - Define CI/CD pipeline:

stages:
  - build
  - deploy

docker-build:
  stage: build
  script:
    - docker build -t <account_id>.dkr.ecr.us-east-1.amazonaws.com/my-app:latest .
    - docker push <account_id>.dkr.ecr.us-east-1.amazonaws.com/my-app:latest

deploy:
  stage: deploy
  script:
    - kubectl apply -f deployment.yaml

🚀 Best Practices

✅ Use Terraform remote state with S3 + DynamoDB✅ Implement secrets management with AWS Secrets Manager✅ Use Helm charts for better Kubernetes deployments✅ Implement ArgoCD ApplicationSets for multi-cluster deployments✅ Integrate AWS CloudWatch for monitoring

❓ FAQs

1️⃣ How do I update my app after changes?

Push changes to the repository, and ArgoCD will automatically sync and deploy.

2️⃣ How do I rollback a deployment?

argocd app rollback my-app 1

3️⃣ Can I integrate AWS ALB with EKS?

Yes! Use the AWS ALB Ingress Controller.

4️⃣ How do I monitor the application?

Use AWS CloudWatch and kubectl logs -f <pod-name> for debugging.

Share your thoughts below! 👇

📢 Have questions or feedback? Drop a comment below or connect with me on Twitter/X@spysood!

Originally published on Medium.