implementing-gitops

Implement GitOps continuous delivery for Kubernetes using declarative, pull-based deployment models where Git serves as the single source of truth for infrastructure and application configuration.

When to Use

Use GitOps workflows for:

• Kubernetes Deployments: Automating application and infrastructure deployments to Kubernetes clusters
• Multi-Cluster Management: Managing deployments across development, staging, production, and edge clusters
• Continuous Delivery: Implementing pull-based CD pipelines with automated reconciliation
• Drift Detection: Automatically detecting and correcting configuration drift from desired state
• Audit Requirements: Maintaining complete audit trails via Git commits for compliance
• Progressive Delivery: Implementing canary, blue-green, or rolling deployment strategies
• Disaster Recovery: Enabling rapid cluster recovery with GitOps bootstrap processes

Trigger keywords: "deploy to Kubernetes", "ArgoCD setup", "Flux bootstrap", "GitOps pipeline", "environment promotion", "multi-cluster deployment", "automated reconciliation"

Core GitOps Principles

1. Git as Single Source of Truth

All system configuration stored in Git repositories. No manual kubectl apply or cluster modifications. Declarative manifests (YAML) for all Kubernetes resources, environment-specific overlays, infrastructure configuration, and application deployments.

2. Pull-Based Deployment

Operators running inside clusters pull changes from Git and apply them automatically. Benefits include no cluster credentials in CI/CD pipelines, support for air-gapped environments, self-healing through continuous reconciliation, and simplified CI/CD.

3. Automated Reconciliation

GitOps operators continuously compare actual cluster state with desired state in Git and reconcile differences through a continuous loop: watch Git, compare live state, apply differences, report status, repeat.

4. Declarative Configuration

Use declarative Kubernetes manifests (not imperative scripts) to define desired state.

Tool Selection

ArgoCD vs Flux

| Decision Factor | Choose ArgoCD | Choose Flux | |----------------|---------------|-------------| | Team Preference | Visual management with web UI | CLI/API-first workflows | | Learning Curve | Easier onboarding with UI | Steeper but more flexible | | Architecture | Monolithic, stateful controller | Modular, stateless controllers | | Multi-Tenancy | Built-in RBAC and projects | Kubernetes-native RBAC | | Resource Usage | Higher (includes UI components) | Lower (minimal controllers) | | Best For | Transitioning to GitOps | Platform engineering |

Hybrid Approach: Some teams use Flux for infrastructure and ArgoCD for applications.

For ArgoCD implementation patterns, see references/argocd-patterns.md For Flux implementation patterns, see references/flux-patterns.md For Kustomize overlay patterns, see references/kustomize-overlays.md

Quick Start

ArgoCD Installation

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

Basic Application:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: myapp
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/org/repo.git
    targetRevision: HEAD
    path: k8s/overlays/prod
  destination:
    server: https://kubernetes.default.svc
    namespace: myapp
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

Flux Bootstrap

flux bootstrap github \
  --owner=myorg \
  --repository=fleet-infra \
  --branch=main \
  --path=clusters/production

Basic Kustomization:

apiVersion: kustomize.toolkit.fluxcd.io/v1
kind: Kustomization
metadata:
  name: myapp
  namespace: flux-system
spec:
  interval: 10m
  path: "./k8s/prod"
  prune: true
  sourceRef:
    kind: GitRepository
    name: myapp

For complete examples, see examples/argocd/ and examples/flux/

Environment Promotion

Branch-Based Strategy: dev branch → staging branch → main branch (prod) Kustomize-Based Strategy: k8s/base/ → k8s/overlays/{dev,staging,prod}/

Promotion Process:

1. Merge code changes to main branch
2. CI builds container image with tag
3. Update image tag in environment overlay (Git commit)
4. GitOps operator detects change and deploys
5. Test in environment
6. Promote to next environment by updating Git

For multi-environment ApplicationSet patterns, see references/argocd-patterns.md

Multi-Cluster Management

ArgoCD: Register external clusters with argocd CLI, use ApplicationSets to generate Applications per cluster, manage from single ArgoCD instance.

Flux: Bootstrap Flux per cluster, use same Git repo with cluster-specific paths, configure remote clusters via kubeConfig secrets.

For detailed multi-cluster patterns, see references/multi-cluster.md

Progressive Delivery

Canary Deployments: Gradually shift traffic to new version, monitor metrics during rollout, automated rollback on failures.

Blue-Green Deployments: Deploy new version alongside old, switch traffic atomically, instant rollback if issues detected.

ArgoCD: Use Argo Rollouts for progressive delivery Flux: Integrate Flagger for automated canary analysis

For progressive delivery strategies and Argo Rollouts examples, see references/progressive-delivery.md

Secret Management

GitOps requires storing configuration in Git, but secrets must be protected.

| Tool | Approach | Security | Complexity | |------|----------|----------|------------| | Sealed Secrets | Encrypt secrets for Git | Medium | Low | | SOPS | Encrypt files with KMS | High | Medium | | External Secrets | Reference external vaults | High | Medium | | HashiCorp Vault | Central secret management | Very High | High |

For secret management integration patterns, see references/secret-management.md

Drift Detection and Remediation

GitOps operators continuously monitor for drift between Git (desired state) and cluster (actual state).

ArgoCD Automatic Self-Healing:

syncPolicy:
  automated:
    prune: true      # Remove resources not in Git
    selfHeal: true   # Revert manual changes

Flux Automatic Reconciliation:

spec:
  interval: 10m    # Check every 10 minutes
  prune: true      # Remove resources not in Git
  force: true      # Force apply on conflicts

Manual Operations:

# ArgoCD
argocd app get myapp           # View sync status
argocd app diff myapp          # Show differences
argocd app sync myapp          # Manually trigger sync

# Flux
flux get kustomizations              # View sync status
flux reconcile kustomization myapp   # Force immediate sync

For drift detection strategies and troubleshooting, see references/drift-remediation.md

Sync Hooks and Lifecycle

Execute operations before/after syncs using hooks.

PreSync Hook (Database Migration):

apiVersion: batch/v1
kind: Job
metadata:
  annotations:
    argocd.argoproj.io/hook: PreSync
    argocd.argoproj.io/hook-delete-policy: HookSucceeded

PostSync Hook (Smoke Test):

apiVersion: batch/v1
kind: Job
metadata:
  annotations:
    argocd.argoproj.io/hook: PostSync

For complete sync hook examples, see examples/argocd/sync-hooks.yaml

Monitoring and Observability

Key Metrics

• Sync Status: OutOfSync, Synced, Unknown
• Sync Frequency: How often reconciliation occurs
• Drift Detection: Time to detect configuration drift
• Sync Duration: Time to apply changes
• Failure Rate: Failed syncs and causes

ArgoCD Metrics: Exposed at /metrics endpoint (argocd_app_sync_total, argocd_app_info) Flux Metrics: From controllers (gotk_reconcile_condition, gotk_reconcile_duration_seconds)

Troubleshooting

Common Issues

Sync Stuck/OutOfSync:

• Check Git repository accessibility
• Verify manifests are valid YAML
• Review sync logs for errors
• Check resource finalizers

Self-Heal Not Working:

• Verify selfHeal enabled in syncPolicy
• Check operator has write permissions
• Review resource ownership labels

Secrets Not Decrypting:

• Verify SOPS/ESO controllers installed
• Check KMS/Vault credentials
• Review encryption key configuration

CLI Quick Reference

ArgoCD Commands

argocd app create <name>          # Create application
argocd app get <name>              # View status
argocd app sync <name>             # Trigger sync
argocd app diff <name>             # Show drift
argocd app list                    # List all applications

Flux Commands

flux create source git <name>      # Create Git source
flux create kustomization <name>   # Create kustomization
flux get all                       # View all resources
flux reconcile <kind> <name>       # Force reconciliation
flux logs                          # View controller logs

Kustomize Commands

kustomize build k8s/overlays/prod  # Preview generated YAML
kubectl apply -k k8s/overlays/prod # Apply directly
kubectl diff -k k8s/overlays/prod  # Show differences

Installation Scripts

Use the provided installation scripts for quick setup:

# Install ArgoCD
./scripts/install-argocd.sh

# Bootstrap Flux
export GITHUB_TOKEN=<token>
export GITHUB_OWNER=<org>
export GITHUB_REPO=fleet-infra
./scripts/install-flux.sh

# Check for drift
./scripts/check-drift.sh

# Promote environment
./scripts/promote-env.sh dev staging

Example Files

Complete working examples provided in examples/ directory:

ArgoCD Examples:

• examples/argocd/application.yaml - Basic Application
• examples/argocd/applicationset.yaml - Multi-environment ApplicationSet
• examples/argocd/progressive-rollout.yaml - Progressive rollout strategy
• examples/argocd/sync-hooks.yaml - PreSync/PostSync hooks

Flux Examples:

• examples/flux/gitrepository.yaml - Git source configuration
• examples/flux/kustomization.yaml - Kustomization controller
• examples/flux/helmrelease.yaml - Helm release management
• examples/flux/ocirepository.yaml - OCI artifact source

Kustomize Examples:

• examples/kustomize/base/ - Base configuration
• examples/kustomize/overlays/{dev,staging,prod}/ - Environment overlays

Rollout Examples:

• examples/rollouts/canary.yaml - Canary deployment with Argo Rollouts
• examples/rollouts/blue-green.yaml - Blue-green deployment strategy

Related Skills

• kubernetes-operations: Kubernetes fundamentals and resource management
• infrastructure-as-code: Provisioning clusters that GitOps deploys to
• building-ci-pipelines: CI builds images, GitOps deploys them
• secret-management: Vault/ESO integration with GitOps
• deploying-applications: GitOps as the deployment mechanism

Summary

GitOps provides automated, declarative continuous delivery for Kubernetes with Git as the single source of truth. Choose ArgoCD for UI-driven workflows or Flux for CLI/API-first approaches. Implement automated reconciliation, drift detection, and progressive delivery for reliable deployments at scale. Integrate secret management, multi-cluster orchestration, and disaster recovery for production-grade GitOps workflows.