GitOps

What is GitOps?

GitOps uses Git as the single source of truth for declarative infrastructure and applications. Changes are made via Git commits, and automated processes sync the desired state.

Core Principles

1. Declarative: System state described declaratively
2. Versioned: All changes in Git
3. Automated: Automatic sync from Git
4. Reconciliation: Continuous drift detection

GitOps Workflow

Developer → Git Commit → Git Repository
                              ↓
                         GitOps Operator
                              ↓
                    Kubernetes Cluster

ArgoCD Example

# Application manifest
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/myorg/myapp
    targetRevision: main
    path: k8s
  destination:
    server: https://kubernetes.default.svc
    namespace: production
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

Multi-Stack GitOps

repo/
├── apps/
│   ├── angular-frontend/
│   │   ├── deployment.yaml
│   │   ├── service.yaml
│   │   └── ingress.yaml
│   ├── dotnet-api/
│   │   ├── deployment.yaml
│   │   ├── service.yaml
│   │   └── configmap.yaml
│   └── nodejs-service/
│       ├── deployment.yaml
│       ├── service.yaml
│       └── secret.yaml
└── infrastructure/
    ├── postgres/
    │   ├── statefulset.yaml
    │   └── service.yaml
    ├── mongodb/
    │   ├── statefulset.yaml
    │   └── service.yaml
    └── redis/
        ├── deployment.yaml
        └── service.yaml

Flux CD

# GitRepository
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: GitRepository
metadata:
  name: myapp
  namespace: flux-system
spec:
  interval: 1m
  url: https://github.com/myorg/myapp
  ref:
    branch: main

---
# Kustomization
apiVersion: kustomize.toolkit.fluxcd.io/v1beta2
kind: Kustomization
metadata:
  name: myapp
  namespace: flux-system
spec:
  interval: 5m
  path: ./k8s
  prune: true
  sourceRef:
    kind: GitRepository
    name: myapp

Environment Promotion

# Dev environment
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp-dev
spec:
  source:
    repoURL: https://github.com/myorg/myapp
    targetRevision: develop
    path: k8s/overlays/dev
  destination:
    namespace: dev

---
# Staging environment
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp-staging
spec:
  source:
    repoURL: https://github.com/myorg/myapp
    targetRevision: main
    path: k8s/overlays/staging
  destination:
    namespace: staging

---
# Production environment
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp-prod
spec:
  source:
    repoURL: https://github.com/myorg/myapp
    targetRevision: v1.0.0  # Tag for production
    path: k8s/overlays/production
  destination:
    namespace: production

Kustomize Overlays

# base/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 1
  template:
    spec:
      containers:
        - name: myapp
          image: myapp:latest

---
# overlays/production/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
bases:
  - ../../base
replicas:
  - name: myapp
    count: 5
images:
  - name: myapp
    newTag: v1.0.0

CI/CD Integration

# GitHub Actions
name: GitOps Deploy

on:
  push:
    branches: [main]

jobs:
  update-manifests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      
      - name: Update image tag
        run: |
          cd k8s
          kustomize edit set image myapp=myapp:${{ github.sha }}
      
      - name: Commit changes
        run: |
          git config user.name "GitHub Actions"
          git config user.email "actions@github.com"
          git add k8s/
          git commit -m "Update image to ${{ github.sha }}"
          git push

Secrets Management

# Sealed Secrets
apiVersion: bitnami.com/v1alpha1
kind: SealedSecret
metadata:
  name: myapp-secrets
spec:
  encryptedData:
    database-url: AgBx7Qw...encrypted...
    api-key: AgCy8Rx...encrypted...

Benefits

1. Git as source of truth: All changes tracked
2. Audit trail: Complete history
3. Easy rollback: Git revert
4. Declarative: Desired state in code
5. Automated: Continuous reconciliation

Interview Tips

• Explain GitOps: Git-driven operations
• Show ArgoCD/Flux: GitOps tools
• Demonstrate multi-stack: Multiple applications
• Discuss environments: Dev, staging, prod
• Mention benefits: Audit trail, rollback
• Show Kustomize: Configuration management

Summary

GitOps uses Git as single source of truth for infrastructure and applications. ArgoCD and Flux CD automate deployment from Git. Supports multi-stack applications and databases. Use Kustomize for environment-specific configurations. Provides audit trail and easy rollback. Essential for modern Kubernetes deployments.