Lab 09: Flux GitOps

Objectives

• ✅ Install Flux on cluster
• ✅ Create HelmRelease manifests
• ✅ Set up Git synchronization
• ✅ Test auto-sync on Git push
• ✅ Monitor Flux reconciliation

Prerequisites

• Lab 08 complete
• GitHub account (for storing config)
• Flux CLI installed
• ~1.5 hours

Step 1: Install Flux

# Check Flux prerequisites
flux check --pre

# Bootstrap Flux with GitHub
# (Creates flux-system namespace, installs controllers)
flux bootstrap github \
  --owner=YOUR_GITHUB_USERNAME \
  --repo=devops-learning-config \
  --branch=main \
  --path=./clusters/training

# You'll be prompted to create a personal access token
# Creating repo in your GitHub account automatically

Verify installation:

# Check Flux components
kubectl get pods -n flux-system

# Should see:
# - helm-controller
# - source-controller
# - kustomize-controller
# - notification-controller

Step 2: Create HelmRelease

Create helmrelease.yaml:

apiVersion: helm.toolkit.fluxcd.io/v2beta1
kind: HelmRelease
metadata:
  name: myapp
  namespace: default
spec:
  interval: 5m  # Check Git every 5 minutes
  releaseName: myapp
  chart:
    spec:
      chart: ./myapp-chart  # Local chart
      sourceRef:
        kind: GitRepository
        name: flux-system
        namespace: flux-system
  values:
    replicaCount: 3
    image:
      tag: "1.0.0"
    resources:
      requests:
        memory: "256Mi"
        cpu: "100m"
      limits:
        memory: "512Mi"
        cpu: "500m"

Step 3: Create HelmRepository Source

For external charts:

apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: HelmRepository
metadata:
  name: myrepo
  namespace: flux-system
spec:
  interval: 5m
  url: https://charts.example.com
  secretRef:
    name: helm-credentials  # Optional: for private repos

Step 4: Push Config to Git

# Clone the Flux repo that was created
git clone https://github.com/YOUR_USERNAME/devops-learning-config
cd devops-learning-config

# Create directory
mkdir -p clusters/training

# Add HelmRelease
cp helmrelease.yaml clusters/training/

# Commit and push
git add clusters/training/helmrelease.yaml
git commit -m "Add myapp HelmRelease"
git push origin main

Step 5: Monitor Flux Reconciliation

# Watch Flux sync the config
kubectl get helmrelease -w

# Check status
kubectl describe helmrelease myapp

# View controller logs
kubectl logs -f -n flux-system deployment/helm-controller

# Check if release created
helm list

Step 6: Test Auto-Update on Git Push

Edit helmrelease.yaml in Git:

# Change replicas from 3 to 5
spec:
  values:
    replicaCount: 5

Push to Git:

git add clusters/training/helmrelease.yaml
git commit -m "Scale up to 5 replicas"
git push origin main

# Watch Flux detect and apply change
watch kubectl get deployment myapp -o wide
# Should scale to 5 replicas automatically

Step 7: Drift Detection

Intentionally change cluster:

# Manually scale down
kubectl scale deployment myapp --replicas=2

# Flux detects drift
watch kubectl get deployment myapp
# After ~5 minutes, scales back to 5 (from Git)

Step 8: Alerting (Optional)

Set up Slack notifications:

apiVersion: notification.toolkit.fluxcd.io/v1beta2
kind: Alert
metadata:
  name: deployment-alerts
  namespace: flux-system
spec:
  providerRef:
    name: slack
  eventSeverity: error
  eventSources:
  - kind: HelmRelease
    name: '*'

---
apiVersion: notification.toolkit.fluxcd.io/v1beta2
kind: Provider
metadata:
  name: slack
  namespace: flux-system
spec:
  type: slack
  address: https://hooks.slack.com/services/YOUR/WEBHOOK/URL

Create secret:

kubectl create secret generic slack-webhook \
  -n flux-system \
  --from-literal=slack-webhook=https://hooks.slack.com/services/YOUR/WEBHOOK

Step 9: Multi-Cluster GitOps

Structure for multiple clusters:

configs/
├── clusters/
│   ├── east/
│   │   ├── helmReleases.yaml
│   │   └── kustomization.yaml
│   │
│   └── west/
│       ├── helmReleases.yaml
│       └── kustomization.yaml
│
└── apps/
    └── myapp-chart/

Each cluster bootstraps to its directory:

# East cluster
flux bootstrap github \
  --owner=YOUR_USERNAME \
  --repo=configs \
  --path=clusters/east

# West cluster
flux bootstrap github \
  --owner=YOUR_USERNAME \
  --repo=configs \
  --path=clusters/west

Validation

# Flux installed
kubectl get pods -n flux-system

# HelmRelease created
kubectl get helmrelease

# Helm release deployed
helm list

# Git source synced
kubectl get gitrepository -n flux-system

# Reconciliation status
kubectl get helmrelease -o wide
# READY should be True

Challenge (Optional)

Implement Kustomization with Flux:

apiVersion: kustomize.toolkit.fluxcd.io/v1
kind: Kustomization
metadata:
  name: myapp
  namespace: flux-system
spec:
  interval: 5m
  path: ./kustomize/overlays/production
  prune: true
  sourceRef:
    kind: GitRepository
    name: flux-system

Cleanup

# Delete Flux
flux uninstall --namespace=flux-system

# Delete HelmRelease
kubectl delete helmrelease myapp

# Delete Git repo (optional)
# rm -rf devops-learning-config/

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Next: Lab 10: Observability