ArgoCD GitOps

Deploy applications automatically from Git using ArgoCD.

Time: ~20 minutes Difficulty: Intermediate

What You Will Learn

• Installing ArgoCD on Minikube with Terraform
• Creating ArgoCD Application resources
• The App-of-Apps pattern
• Auto-sync, self-heal, and auto-prune
• ArgoCD Projects for access control

Prerequisites

• Terraform v1.0+
• Demos simple-app, helm, and kustomize must exist in this repo (ArgoCD deploys them from Git)

Install ArgoCD

cd demos/argocd/terraform/

terraform init
terraform apply

Terraform installs ArgoCD via Helm into the argocd namespace.

Access the ArgoCD UI

# Port-forward the ArgoCD server
kubectl port-forward svc/argocd-server -n argocd 8080:80

# Get the admin password
kubectl -n argocd get secret argocd-initial-admin-secret \
  -o jsonpath="{.data.password}" | base64 -d

Open http://localhost:8080 and log in with username admin and the password above.

Deploy Applications

Option A: App-of-Apps (recommended)

Deploy all applications at once:

kubectl apply -f applications/app-of-apps.yaml

This creates a parent application that manages all child applications:

Application	Source Path	What It Deploys
simple-app	demos/simple-app/manifests	Plain nginx deployment
helm-app	demos/helm/chart	Helm-based web app
kustomize-dev	demos/kustomize/overlays/development	Dev overlay
kustomize-prod	demos/kustomize/overlays/production	Prod overlay

Option B: One at a time

kubectl apply -f applications/1-simple-app.yaml
kubectl apply -f applications/2-helm-app.yaml
kubectl apply -f applications/3a-kustomize-dev.yaml
kubectl apply -f applications/3b-kustomize-prod.yaml

Verify

In the ArgoCD UI, you should see all applications with a green “Synced” and “Healthy” status.

From the CLI:

kubectl get applications -n argocd

What is Happening

applications/
  app-of-apps.yaml         # Meta-application managing all others
  1-simple-app.yaml        # Points to demos/simple-app/manifests
  2-helm-app.yaml          # Points to demos/helm/chart
  3a-kustomize-dev.yaml    # Points to demos/kustomize/overlays/development
  3b-kustomize-prod.yaml   # Points to demos/kustomize/overlays/production

projects/
  project-dev.yaml         # RBAC: restricts which repos and namespaces are allowed

terraform/
  provider.tf              # Helm + Kubernetes providers
  argocd.tf                # ArgoCD Helm release
  variables.tf             # Configurable inputs
  values.yaml              # ArgoCD Helm values
  outputs.tf               # Post-install instructions

Each ArgoCD Application watches a Git path. When you push a change, ArgoCD detects the diff and syncs the cluster to match.

Key sync policies:

• Auto-sync: applies changes without manual approval
• Self-heal: reverts manual cluster edits to match Git
• Auto-prune: deletes resources removed from Git

Experiment

1. Edit demos/simple-app/manifests/deployment.yaml, change replicas: 2 to replicas: 5, commit and push. Watch ArgoCD sync automatically.

2. Manually delete a pod and watch ArgoCD self-heal:

   kubectl delete pod -l app=simple-nginx -n simple-app

3. Check sync status from CLI:

   kubectl get applications -n argocd -o wide

Cleanup

# Remove all applications
kubectl delete -f applications/app-of-apps.yaml

# Uninstall ArgoCD
cd terraform/
terraform destroy

# Remove namespace
kubectl delete namespace argocd

Further Reading

See docs/deep-dive.md for a detailed explanation of GitOps principles, ArgoCD architecture, sync policies, the App-of-Apps pattern, Projects/RBAC, and troubleshooting.

Next Step

Move on to Cert-Manager to automate TLS certificate management.