SaaS Demo on DigitalOcean Kubernetes (DOKS)

This repository contains Terraform code to provision a DOKS cluster and deploy a scalable, autoscaled web app (Flask + Redis) fronted by a DigitalOcean Load Balancer (via Kubernetes Service type LoadBalancer).

Features

• DigitalOcean VPC + DOKS cluster with autoscaling node pool
• Metrics Server (via Helm) to support HPA
• Redis (ClusterIP) for shared hit counter
• Web app Deployment with readiness/liveness probes
• Service type LoadBalancer for public exposure
• HPA v2 scaling based on CPU utilization
• Outputs with kubeconfig and LB hostname

Prerequisites

• Terraform >= 1.5
• Docker & a container registry (Docker Hub or GHCR)
• kubectl & helm (optional locally)
• DigitalOcean Personal Access Token (PAT)

Quick Start

1. Build & push the app image

cd app
docker build -t ghcr.io/<your-user>/saas-hitapp:1.0.0 .
# docker login ghcr.io
docker push ghcr.io/<your-user>/saas-hitapp:1.0.0

2. Provision infra + deploy app

cd terraform
terraform init
terraform plan -var="do_token=$DIGITALOCEAN_TOKEN" -var-file="terraform.tfvars.example"
terraform apply -var="do_token=$DIGITALOCEAN_TOKEN" -var-file="terraform.tfvars.example" -auto-approve

3. Retrieve kubeconfig and test

terraform output -raw kubeconfig > kubeconfig_doks
export KUBECONFIG=$PWD/kubeconfig_doks
kubectl get nodes -o wide
kubectl get svc -n hitapp

4. Access the app

Wait for the Service external hostname to appear:

terraform output load_balancer_hostname
# or:
kubectl get svc hitapp -n hitapp -o jsonpath='{.status.loadBalancer.ingress[0].hostname}'

Open http://<hostname>/ in your browser.

Autoscaling Test

Run a basic CPU load test (example with hey):

hey -z 60s -c 50 http://<hostname>/
kubectl get hpa -n hitapp -w

Cost & Performance Notes (Model)

• Choose the smallest node size that meets your SLOs; start with s-2vcpu-4gb and scale out with HPA.
• Use autoscaling node pools to match capacity to demand.
• Use requests/limits to prevent noisy-neighbor and enable HPA to make informed decisions.
• For exact pricing, refer to DigitalOcean's pricing page and calculator.

Cleanup

cd terraform
terraform destroy -var="do_token=$DIGITALOCEAN_TOKEN" -var-file="terraform.tfvars.example" -auto-approve