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🚀 Argo CD Quick Guide

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. It synchronizes your Kubernetes cluster with configuration defined in a Git repository.

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📌 Key Concepts

• App of Apps: Deploy multiple apps by deploying one root app.
• GitOps: Git is the single source of truth.
• Sync: Argo CD reconciles what’s in the Git repo with what’s in your cluster.
• Kustomize / Helm / Plain YAML / Jsonnet: All supported out of the box.

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🛠️ Install Argo CD

# Create the namespace
kubectl create namespace argocd

# Install Argo CD
kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

# Expose Argo CD API server (for dev only)
kubectl port-forward svc/argocd-server -n argocd 8080:443

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🔐 Login to Argo CD UI

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

Access UI at: https://localhost:8080

Default user: admin

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🚀 Create Your First App (CLI)

argocd login localhost:8080

argocd app create my-app \
  --repo https://github.com/your/repo.git \
  --path k8s/my-app \
  --dest-server https://kubernetes.default.svc \
  --dest-namespace default

argocd app sync my-app

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🎛 Application YAML Example

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: my-app
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/your/repo.git
    targetRevision: HEAD
    path: k8s/my-app
  destination:
    server: https://kubernetes.default.svc
    namespace: default
  syncPolicy:
    automated:
      prune: true
      selfHeal: true
    syncOptions:
      - CreateNamespace=true

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✅ Sync Options

• automated: Argo CD will automatically sync your app.
• prune: Remove orphaned resources not in Git.
• selfHeal: Reapply if someone changes resources manually in the cluster.

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🧩 App of Apps Pattern

Useful for managing multiple apps in a single place.

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: root-app
spec:
  source:
    path: apps
    repoURL: https://github.com/your/repo.git
  ...

Then inside /apps, define more Application YAMLs for each microservice.

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🔧 Argo CD CLI Essentials

argocd app list                            # List apps
argocd app get my-app                     # Show app details
argocd app sync my-app                    # Sync the app
argocd app delete my-app                  # Delete app
argocd app logs my-app                    # Show sync logs

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🔐 RBAC & SSO

• Argo CD supports SSO via OIDC, GitHub, GitLab, etc.
• Use argocd-rbac-cm ConfigMap to configure permissions.

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🧠 Tips

• Use Helm or Kustomize with Argo CD to simplify manifests.
• Combine with Argo Workflows for GitOps pipelines.
• Use resource hooks to customize sync behavior.

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