Gitops Review

GitOps Review

Ortak Doktrin

agents/shared/severity-rubric.md ve agents/shared/escalation-matrix.md default-load sayılır (agents/coordination.md §11). Bu skill'in çıktısı Critical / High / Medium / Low + kanıt formatında olmak zorunda — spekülatif Critical yasak. Sahiplik dışı bulgu ilgili agent'a delege; karar yetkisi eşiği aşılırsa kullanıcı onayı zorunlu.

Felsefe

GitOps = Git tek truth + reconciliation loop. Cluster state Git'i takip eder; manuel kubectl apply drift, audit gap, rollback'i imkansızlaştırır.

• Pull > push. Cluster içindeki controller Git'i çeker; CI cluster'a push etmez (push secret leak yüzeyi).
• Declarative. Hedef state YAML'da; controller arayı kapatır.
• Versiyonlu. Her değişiklik Git commit; revert = git revert.
• Self-healing. Manuel müdahale geri alınır — drift detect+fix.
• Auditability. Git log = deploy audit log; "kim ne zaman deploy etti".

Ne Zaman Kullanılır

• Yeni cluster bootstrap (ArgoCD / Flux kurulum)
• Application-of-applications pattern review
• Sync policy + auto-prune + self-heal kararları
• Sealed-secrets / SOPS / External Secrets entegrasyonu
• Progressive delivery (canary, blue-green) Argo Rollouts / Flagger
• Drift detection / reconciliation
• Multi-cluster / multi-tenant yapı
• RBAC + project boundaries
• Disaster recovery (Git → cluster restore)

Workflow

1) Tool tespit

2) Repository yapısı

App-of-apps (ArgoCD)

gitops-repo/
├── apps/
│   ├── app-of-apps.yaml              # ana Application: tüm app'leri create eder
│   └── apps/
│       ├── api-svc.yaml              # Application
│       ├── checkout-svc.yaml
│       └── frontend.yaml
├── infrastructure/
│   ├── ingress-nginx.yaml
│   ├── cert-manager.yaml
│   ├── monitoring.yaml
│   └── ...
└── projects/
    ├── payments.yaml                  # AppProject (RBAC boundary)
    └── platform.yaml

Mono-repo vs multi-repo

• App config (Helm values, kustomize overlays) servis repo'sunda veya ayrı GitOps repo.
• Recommended: 1 GitOps repo per cluster veya per env.
• Branching: main = current state; environment branch'leri (prod branch) ya da per-env directory tercih.

3) Sync policy review

ArgoCD Application syncPolicy

spec:
  syncPolicy:
    automated:
      prune: true            # Git'te silinen → cluster'dan da sil
      selfHeal: true         # manuel değişiklik → revert
    syncOptions:
      - CreateNamespace=true
      - PruneLast=true
      - ApplyOutOfSyncOnly=true
      - ServerSideApply=true # büyük CRD için
    retry:
      limit: 5
      backoff: { duration: 5s, factor: 2, maxDuration: 3m }

Kararlar:

• automated.prune — staging'de on; prod'da dikkatli (yanlışlıkla silme).
• selfHeal — drift'i kapatır; ama acil müdahale gereken incident'ta manual override'ı revert eder. Toggle planı dokumented olmalı.
• CreateNamespace=true — namespace YAML'da yoksa oluştur (genelde uygun).

4) Sealed-secrets / SOPS / External Secrets

Yasak: plain Secret YAML Git'te. Hardcode secret = supply chain breach.

5) Progressive delivery

Argo Rollouts (canary)

apiVersion: argoproj.io/v1alpha1
kind: Rollout
spec:
  strategy:
    canary:
      steps:
        - setWeight: 10
        - pause: { duration: 5m }
        - setWeight: 25
        - analysis:
            templates:
              - templateName: success-rate
            args:
              - name: service-name
                value: api-svc-canary
        - pause: { duration: 5m }
        - setWeight: 50
        - pause: { duration: 10m }
        - setWeight: 100
      analysis:
        templates: [{templateName: success-rate-fast}]
        startingStep: 1

Analysis Template

apiVersion: argoproj.io/v1alpha1
kind: AnalysisTemplate
metadata:
  name: success-rate
spec:
  args:
    - name: service-name
  metrics:
    - name: success-rate
      interval: 1m
      successCondition: result[0] >= 0.99
      failureLimit: 3
      provider:
        prometheus:
          address: http://prometheus.monitoring:9090
          query: |
            sum(rate(http_requests_total{service="{{args.service-name}}",code!~"5.."}[2m]))
            / sum(rate(http_requests_total{service="{{args.service-name}}"}[2m]))

Kararlar:

• Step yüzdeleri: 10/25/50/100 (yaygın) veya 5/25/50/100 (dikkatli).
• Pause süre: Analysis için yeterli sample (5-10 dk).
• Abort eşik: success rate < %99 → otomatik abort (failureLimit=3).
• Manual gate: prod'da analysis fail → manuel onay (auto-promote yasak).

6) Drift detection

• ArgoCD OutOfSync durumu — sync policy off ise alert.
• Flux Reconciliation Failed — controller log'u izle.
• Diff: argocd app diff <app> veya flux diff kustomization <name>.
• Drift sebepleri:
  • Manuel kubectl apply (insan).
  • Webhook controller (cert-manager, external-dns).
  • HPA, VPA (otomatik scale değişikliği — ignoreDifferences kullan).
• ignoreDifferences spesifik path için:

  spec:
    ignoreDifferences:
      - group: apps
        kind: Deployment
        jsonPointers:
          - /spec/replicas         # HPA yönetiyor
  

7) RBAC + AppProject

ArgoCD AppProject = RBAC boundary:

apiVersion: argoproj.io/v1alpha1
kind: AppProject
metadata:
  name: payments
spec:
  sourceRepos:
    - https://github.com/acme/gitops-payments.git
  destinations:
    - namespace: payments-*
      server: https://kubernetes.default.svc
  clusterResourceWhitelist:
    - { group: '', kind: Namespace }
  namespaceResourceBlacklist:
    - { group: '', kind: ResourceQuota }
  roles:
    - name: payments-deployer
      policies:
        - p, proj:payments:payments-deployer, applications, sync, payments/*, allow
      groups:
        - acme-org:payments-team

Kurallar:

• Default * repo veya * destination yasak prod'da.
• clusterResourceWhitelist minimum (Namespace/CRD).
• Role assign Git'te dokumented.

8) Disaster recovery

• Cluster restore: yeni cluster + ArgoCD/Flux + GitOps repo → reconcile.
• Backup: Velero stateful kaynaklar (PVC, Secret).
• Drill: 6 ayda bir cluster sıfırdan kur, restore süresi ölç.

9) Multi-cluster / multi-tenant

• App-of-apps per cluster: dev/staging/prod ayrı app-of-apps.
• Single ArgoCD + multi-cluster: cluster credential Secret.
• Flux multi-tenancy: Kustomization serviceAccountName per-tenant.

10) Observability

• ArgoCD: argocd-server Prometheus metric (argocd_app_info, argocd_app_sync_total).
• Flux: gotk- metric.
• Alert: argocd_app_health Degraded veya OutOfSync > 5 dk.
• Dashboard: app health grid, sync history.

Checklist

• App-of-apps pattern (veya equivalent)
• Per-env ayrı yapı (dev/staging/prod)
• Sync policy explicit (prune + selfHeal toggle planı)
• Sealed-secrets / SOPS / External Secrets — plain Secret yok
• Progressive delivery (canary/blue-green) prod'da
• Analysis template + abort eşik
• Drift alert (OutOfSync > 5 dk)
• ignoreDifferences minimum + dokumented
• RBAC: AppProject + role + group binding
• DR plan: cluster restore drill
• Multi-cluster yapı dokumented
• Observability: metric + dashboard + alert
• kubectl apply manuel yasak (drift kaynağı)

Antipattern

• Manuel kubectl apply — Git'i atla, drift garanti.
• Plain Secret Git'te — supply chain breach.
• autoSync off + manual sync — GitOps amacı kayıp.
• ignoreDifferences = all — drift invisible.
• Auto-promote canary — analysis fail'de prod'a girer.
• * repo / * destination AppProject'te — RBAC etkisiz.
• Branching environment (env=branch) — mono-repo'da divergence; per-env directory tercih.
• Mono-cluster ArgoCD prod'a + dev'e — blast radius büyük.
• Sealed-secrets master key Git'te — yenisi çıksa yine encrypt; eski'sini revoke.
• DR drill yok — cluster destroyed → Git OK ama state restore yok (Velero).
• Argo Rollouts step % 0/100 — canary değil, regular rolling.
• Analysis success rate sadece HTTP 200 — slow request'i sayar, p99 latency dahil olmalı.

Örnek Agent Davranışı

User: /gitops-review apps/
Agent (platform-engineer):
1. Tool tespit: ArgoCD + Argo Rollouts + sealed-secrets.
2. Repo yapı: app-of-apps ✓, per-env directory (dev/staging/prod) ✓.
3. Sync policy: prod app'lerinde `selfHeal: true` — incident sırasında
   manuel override'ı revert eder (High; toggle planı eksik).
4. Sealed-secrets: 14 SealedSecret Git'te ✓; ama `Secret` plain 2 yerde
   `apps/legacy/*` (Critical — supply chain).
5. Argo Rollouts: api-svc canary 10/50/100 (3 step, çok hızlı); abort eşik
   manual (auto fail yok). Önerilen: 5/25/50/100 + `failureLimit: 3`.
6. Drift: `ignoreDifferences = all` 3 app'te (`monitoring`, `cert-manager`,
   `legacy-billing`) — invisible drift.
7. RBAC: AppProject `default` her şey allow ediyor — namespace + repo
   whitelist'e geç.
8. DR: drill kayıt yok — quarter'da bir restore drill öner.
9. Output: 3 Critical + 5 High + 4 Medium issue + diff özet.

Çıktı Formatı

# GitOps Review: <repo>

## Tool / Yapı
- ArgoCD/Flux + version + repo layout

## Sync Policy
- prune / selfHeal / retry / serverSideApply tablosu

## Critical / High / Medium / Low

## Diff (özet)
```yaml
# fix snippet

Action Items

| Öncelik | Aksiyon | Sahip | Bitiş | Issue |