k8s-gitops-lab

GitOps workflow with Helm & ArgoCD on Kubernetes

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What is this?

A production-grade GitOps lab that demonstrates end-to-end Kubernetes deployment using Helm and ArgoCD.

A simple Go/Gin API is packaged as a Helm chart and deployed to two environments — develop and staging — via ArgoCD's App of Apps pattern using an ApplicationSet.

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Architecture

app-of-apps.yaml
    └── ApplicationSet (argocd/)
            ├── app-dev      → helm/app-chart + gitops/dev/values.yaml     → develop namespace
            └── app-staging  → helm/app-chart + gitops/staging/values.yaml → staging namespace

One commit to git → ArgoCD syncs both environments automatically.

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Stack

Tool	Role
Go + Gin	Simple API with /health, /ready, /version
Docker	Multi-stage image build
Helm v3	Kubernetes packaging — chart written from scratch
ArgoCD	GitOps continuous delivery
ApplicationSet	Generates multi-environment apps from a single template
App of Apps	Single entry point manages all ArgoCD applications
Traefik	Ingress controller (built into k3s)
k3s	Local Kubernetes cluster

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Helm Chart Features

Chart written from scratch — no helm create scaffolding.

• Deployment with configurable replicas, image, and environment
• Service with configurable type and port
• Ingress with TLS and className support
• ConfigMap for environment injection via envFrom
• HPA — Horizontal Pod Autoscaler (CPU + Memory)
• _helpers.tpl — shared labels via named templates
• livenessProbe + readinessProbe on /health and /ready
• securityContext — non-root, read-only filesystem, dropped capabilities
• imagePullSecrets — private registry support
• resources — CPU/memory requests and limits

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Repository Structure

k8s-gitops-lab/
├── app-of-apps.yaml          ← single apply to bootstrap everything
├── app/
│   ├── main.go               ← Go/Gin API
│   ├── Dockerfile
│   └── .dockerignore
├── argocd/
│   └── applicationset.yaml   ← generates app-dev and app-staging
├── gitops/
│   ├── dev/values.yaml       ← dev environment overrides
│   └── staging/values.yaml   ← staging environment overrides
└── helm/
    └── app-chart/
        ├── Chart.yaml
        ├── values.yaml
        └── templates/
            ├── _helpers.tpl
            ├── configmap.yaml
            ├── deployment.yaml
            ├── hpa.yaml
            ├── ingress.yaml
            └── service.yaml

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Screenshots

All Applications — Healthy & Synced

App of Apps Tree

app-dev Resources

app-staging Resources

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How to Run

Prerequisites

• k3s or any Kubernetes cluster
• Helm v3
• kubectl
• Docker Hub account

1. Install ArgoCD

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

2. Create Docker Hub secret

kubectl create secret docker-registry dockerhub \
  --docker-username=<username> \
  --docker-password=<token> \
  --docker-server=https://index.docker.io/v1/ \
  --namespace develop

kubectl create secret docker-registry dockerhub \
  --docker-username=<username> \
  --docker-password=<token> \
  --docker-server=https://index.docker.io/v1/ \
  --namespace staging

3. Create TLS secret

# Generate self-signed certificate
openssl req -x509 -nodes -days 365 -newkey rsa:2048 \
  -keyout tls.key -out tls.crt \
  -subj "/CN=app-chart.local"

# Create secret in both namespaces
kubectl create secret tls app-chart-tls \
  --cert=tls.crt --key=tls.key \
  --namespace develop

kubectl create secret tls app-chart-tls \
  --cert=tls.crt --key=tls.key \
  --namespace staging

# Remove local files — never commit these
rm tls.crt tls.key

5. Bootstrap with App of Apps

kubectl apply -f app-of-apps.yaml

ArgoCD will automatically create both environments from git.

6. Access ArgoCD UI

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

7. Add local DNS

echo "127.0.0.1 dev.app-chart.local staging.app-chart.local" | sudo tee -a /etc/hosts

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GitOps Flow

git push
    └── ArgoCD detects change (auto-sync)
            └── helm template + apply
                    ├── develop namespace updated
                    └── staging namespace updated

No manual helm upgrade needed — git is the single source of truth.

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API Endpoints

Endpoint	Description
GET /health	Liveness check — returns { "status": "up" }
GET /ready	Readiness check — returns { "status": "ready" }
GET /version	App version and environment

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_{Built as part of a DevOps portfolio — next up: vault-cicd-lab}