ArgoCD GitOps Tutorial 2025 - Continuous Deployment

🚀 Why ArgoCD in 2025?

ArgoCD leads the GitOps revolution with 65% enterprise adoption. It automates Kubernetes deployments using Git as the single source of truth - ensuring consistency, auditability, and faster deployments.

Quick Facts:

✅ 80% faster deployment cycles
✅ Zero-downtime rolling updates
✅ Salary Impact: GitOps skills add ₹8-20 LPA
✅ 65% adoption in enterprise Kubernetes environments
✅ Git as source of truth - complete audit trail
✅ CNCF Graduated project - production-ready

📦 Quick Installation

Method 1: Using Helm (Recommended)

# Add ArgoCD Helm repository
helm repo add argo https://argoproj.github.io/argo-helm
helm repo update

# Install ArgoCD
helm install argocd argo/argo-cd \
  --namespace argocd \
  --create-namespace \
  --set server.service.type=LoadBalancer

# Verify installation
kubectl get pods -n argocd
kubectl get svc -n argocd

Method 2: Using kubectl

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

# Wait for pods to be ready
kubectl wait --for=condition=Ready pods --all -n argocd --timeout=300s

Access ArgoCD UI:

# Port forward to access UI
kubectl port-forward svc/argocd-server -n argocd 8080:443

# Or expose via LoadBalancer
kubectl patch svc argocd-server -n argocd -p '{  "spec": {  "type": "LoadBalancer"  }  }'

Login Credentials:

🌐 URL: https://localhost:8080
👤 Username: admin
🔑 Get Password:

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

# Install ArgoCD CLI
curl -sSL -o argocd-linux-amd64 https://github.com/argoproj/argo-cd/releases/latest/download/argocd-linux-amd64
sudo install -m 555 argocd-linux-amd64 /usr/local/bin/argocd

# Login via CLI
argocd login localhost:8080 --username admin --password <password>

🎯 Core Concepts

📦 Application

A group of Kubernetes resources defined in a Git repository. ArgoCD continuously monitors and syncs these resources to your cluster.

🔄 Sync Policy

Defines how ArgoCD deploys changes - automated (instant) or manual (approval required). Includes self-heal and prune options.

💚 Health Status

Real-time health of deployed resources: Healthy, Progressing, Degraded, Suspended, Missing, or Unknown.

🔍 Sync Status

Comparison between Git (desired state) and cluster (actual state): Synced, OutOfSync, or Unknown.

Additional Key Concepts:

✅ Project: Logical grouping of applications with RBAC
✅ Repository: Git repo containing Kubernetes manifests
✅ Cluster: Target Kubernetes cluster for deployment
✅ Sync Wave: Control deployment order with annotations
✅ Resource Hook: Execute actions during sync (PreSync, Sync, PostSync)
✅ ApplicationSet: Template for creating multiple applications

📁 Your First Application

Create Application YAML (app.yaml):

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp
  namespace: argocd
  # Finalizer ensures proper cleanup
  finalizers:
    - resources-finalizer.argocd.argoproj.io
spec:
  # Project for RBAC
  project: default

  # Source repository
  source:
    repoURL: https://github.com/your-repo/manifests.git
    targetRevision: main
    path: k8s/

    # For Helm charts
    # helm:
    #   valueFiles:
    #     - values.yaml

    # For Kustomize
    # kustomize:
    #   namePrefix: prod-

  # Destination cluster and namespace
  destination:
    server: https://kubernetes.default.svc
    namespace: production

  # Sync policy
  syncPolicy:
    automated:
      prune: true        # Delete resources not in Git
      selfHeal: true     # Auto-sync on drift
      allowEmpty: false  # Prevent empty sync
    syncOptions:
      - CreateNamespace=true  # Auto-create namespace
      - PruneLast=true        # Prune after sync
    retry:
      limit: 5
      backoff:
        duration: 5s
        factor: 2
        maxDuration: 3m

# Apply the application
kubectl apply -f app.yaml

# Or create via ArgoCD CLI
argocd app create myapp \
  --repo https://github.com/your-repo/manifests.git \
  --path k8s \
  --dest-server https://kubernetes.default.svc \
  --dest-namespace production \
  --sync-policy automated \
  --auto-prune \
  --self-heal

# Check application status
argocd app get myapp
argocd app sync myapp

🔄 GitOps Workflow

┌──────────────┐      ┌──────────────┐      ┌──────────────┐
│  Developer   │ ───▶ │  Git Commit  │ ───▶ │ArgoCD Detects│
│ Makes Change │      │  Push Code   │      │   Changes    │
└──────────────┘      └──────────────┘      └──────────────┘
                                                    │
                                                    ▼
┌──────────────┐      ┌──────────────┐      ┌──────────────┐
│ Application  │ ◀─── │   Applies    │ ◀─── │  Compares    │
│  Deployed    │      │   Changes    │      │ Git vs K8s   │
└──────────────┘      └──────────────┘      └──────────────┘
       │
       ▼
┌──────────────────────────────────────────────────────────┐
│              Continuous Monitoring & Sync                │
│  • Health Checks  • Drift Detection  • Auto-Healing     │
└──────────────────────────────────────────────────────────┘

GitOps Benefits:

For Developers:

✅ Git as deployment interface
✅ No kubectl access needed
✅ Easy rollbacks via Git revert
✅ Complete audit trail

For Operations:

✅ Declarative infrastructure
✅ Automated drift correction
✅ Disaster recovery via Git
✅ Multi-cluster consistency

🛠️ Essential Commands

argocd app list                    # List applications
argocd app get myapp              # View application details
argocd app sync myapp             # Manual sync
argocd app history myapp          # Deployment history
argocd app rollback myapp         # Rollback to previous version
argocd repo add https://github.com/your-repo  # Add Git repo

📊 Real Example: Multi-Environment

staging-app.yaml:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp-staging
spec:
  source:
    repoURL: https://github.com/your-repo.git
    path: k8s/overlays/staging
    targetRevision: main
  destination:
    namespace: staging
  syncPolicy:
    automated: {}

production-app.yaml:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp-production
spec:
  source:
    repoURL: https://github.com/your-repo.git
    path: k8s/overlays/production
    targetRevision: main
  destination:
    namespace: production
  syncPolicy:
    automated:
      selfHeal: true
      prune: true

🔐 Security Best Practices

1. RBAC Configuration:

apiVersion: argoproj.io/v1alpha1
kind: AppProject
metadata:
  name: production-project
spec:
  sourceRepos:
    - 'https://github.com/your-org/*'
  destinations:
    - namespace: production
      server: https://kubernetes.default.svc
  roles:
    - name: dev-team
      policies:
        - p, proj:production-project:dev-team, applications, get, production-project/*, allow

2. Use SSO Integration:

Configure OAuth2 (GitHub, GitLab, Google)
Enable RBAC with group policies
Audit logs enabled

🔔 Notifications & Webhooks

apiVersion: argoproj.io/v1alpha1
kind: ConfigMap
metadata:
  name: argocd-notifications-cm
data:
  service.slack: |
    token: $slack-token
  trigger.on-sync-succeeded: |
    - send: [slack]
  template.app-sync-succeeded: |
    message: |
      Application {{  .app.metadata.name  }}  sync succeeded

📈 Advanced Features 2025

1. ApplicationSet (Multi-cluster):

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: cluster-apps
spec:
  generators:
    - clusters:
        selector:
          matchLabels:
            env: production
  template:
    metadata:
      name: '{{  name  }}  -app'
    spec:
      project: default
      source:
        repoURL: https://github.com/your-repo.git
        targetRevision: main
        path: k8s/
      destination:
        server: '{{  server  }}  '
        namespace: default

2. Health Checks:

spec:
  syncPolicy:
    syncOptions:
      - Validate=true

🛠️ Essential ArgoCD Commands

Common CLI Commands:

# Application Management
argocd app list                           # List all applications
argocd app get myapp                      # View application details
argocd app sync myapp                     # Manual sync
argocd app sync myapp --prune             # Sync and prune
argocd app diff myapp                     # Show differences
argocd app history myapp                  # Deployment history
argocd app rollback myapp 5               # Rollback to revision 5
argocd app delete myapp                   # Delete application

# Repository Management
argocd repo add https://github.com/your-repo  # Add Git repo
argocd repo list                          # List repositories

# Cluster Management
argocd cluster add my-cluster             # Add cluster
argocd cluster list                       # List clusters

# Project Management
argocd proj create myproject              # Create project
argocd proj list                          # List projects

# Monitoring
argocd app logs myapp                     # View application logs
argocd app wait myapp                     # Wait for sync completion
argocd app manifests myapp                # View generated manifests

💡 Pro Tips 2025

Best Practices:

✅ Use Kustomize/Helm: Manage environment-specific configs efficiently
✅ Enable auto-pruning: Clean up removed resources automatically
✅ Set resource hooks: Execute database migrations during sync
✅ Use sync waves: Control deployment order with annotations
✅ App of Apps pattern: Manage multiple applications as one
✅ Implement RBAC: Use projects for team isolation
✅ Enable notifications: Get alerts on Slack/Teams
✅ Use ApplicationSets: Template applications for multi-cluster
✅ Git branch strategy: Use branches for environments
✅ Health checks: Define custom health checks for CRDs
✅ Backup regularly: Export application definitions
✅ Monitor metrics: Use Prometheus for ArgoCD metrics

🚨 Troubleshooting Guide

Common Issues & Solutions:

❌ Sync Failed

Cause: Invalid manifest syntax or missing resources

Solution: Check manifest syntax, validate YAML, review error logs

⚠️ Health Degraded

Cause: Pods not running, failed health checks

Solution: Check pod status, review events, verify resource limits

🔄 OutOfSync

Cause: Git state differs from cluster state

Solution: Run sync, enable auto-sync, check for manual changes

🔒 Access Denied

Cause: Insufficient RBAC permissions

Solution: Check project permissions, verify service account, review RBAC policies

Debug Commands:

# Show differences between Git and cluster
argocd app diff myapp

# View generated manifests
argocd app manifests myapp

# View application logs
argocd app logs myapp

# Get detailed application info
argocd app get myapp --show-params

# Check sync status
kubectl get application myapp -n argocd -o yaml

# View ArgoCD server logs
kubectl logs -n argocd deployment/argocd-server

# View application controller logs
kubectl logs -n argocd deployment/argocd-application-controller

📚 4-Week Learning Path

Week 1: Basics & Installation

✅ Install ArgoCD on Kubernetes cluster
✅ Understand GitOps principles
✅ Navigate ArgoCD UI
✅ Connect first Git repository
✅ Project: Deploy simple Nginx application

Week 2: Application Management

✅ Create applications via UI and YAML
✅ Configure sync policies (auto/manual)
✅ Use Kustomize and Helm charts
✅ Monitor health and sync status
✅ Project: Deploy microservices application

Week 3: Multi-Environment Setup

✅ Set up dev, staging, production environments
✅ Use Kustomize overlays for environment configs
✅ Implement promotion workflows
✅ Configure RBAC and projects
✅ Project: Complete CI/CD pipeline with GitOps

Week 4: Advanced Patterns & Production

✅ ApplicationSets for multi-cluster
✅ Sync waves and resource hooks
✅ Notifications and webhooks
✅ Security best practices and SSO
✅ Disaster recovery and backup
✅ Project: Production-grade multi-cluster setup

💼 Career Impact 2025

Junior DevOps Engineer

Salary: ₹12-18 LPA

Skills: Basic ArgoCD setup, application deployment, Git workflows

Mid-Level SRE/Platform Engineer

Salary: ₹20-35 LPA

Skills: Multi-environment setup, RBAC, ApplicationSets, advanced sync policies

Senior/Architect

Salary: ₹35-55 LPA

Skills: Multi-cluster GitOps, platform engineering, security architecture, disaster recovery

✅ Quick Start Checklist

Week 1-2:

☐ Install ArgoCD on Kubernetes cluster
☐ Access ArgoCD UI and CLI
☐ Connect Git repository
☐ Deploy first application
☐ Understand sync status

Week 3-4:

☐ Configure auto-sync policies
☐ Set up multi-environment
☐ Implement RBAC and projects
☐ Configure notifications
☐ Build production GitOps workflow

Begin GitOps: Your first git push deploys to production!

Remember: Git is now your deployment button. Commit to deploy!