GitOps with Flux CD on AKS

GitOps is a modern operational framework that uses Git as a single source of truth for declarative infrastructure and applications. Flux CD is a CNCF graduated project that enables GitOps for Kubernetes.

What is GitOps?

GitOps brings the following principles to infrastructure management:

• Declarative - Describe the entire system declaratively
• Versioned and immutable - Store canonical desired system state versioned in Git
• Pulled automatically - Software agents automatically pull and apply the desired state
• Continuously reconciled - Software agents continuously observe actual system state

Installing Flux on AKS

Prerequisites

# Install Flux CLI
curl -s https://fluxcd.io/install.sh | sudo bash

# Verify installation
flux check --pre

Bootstrap Flux with GitHub

export GITHUB_TOKEN=<your-token>
export GITHUB_USER=<your-username>

flux bootstrap github \
  --owner=$GITHUB_USER \
  --repository=fleet-infra \
  --branch=main \
  --path=./clusters/my-cluster \
  --personal

This command:

1. Creates a GitHub repository (fleet-infra)
2. Generates Flux manifests
3. Deploys Flux components to your cluster
4. Configures Flux to watch the repository

Structuring Your GitOps Repository

fleet-infra/
├── clusters/
│   ├── production/
│   │   ├── flux-system/     # Flux components
│   │   ├── infrastructure.yaml
│   │   └── apps.yaml
│   └── staging/
│       ├── flux-system/
│       ├── infrastructure.yaml
│       └── apps.yaml
├── infrastructure/
│   ├── sources/             # Git/Helm repositories
│   ├── cert-manager/
│   ├── ingress-nginx/
│   └── monitoring/
└── apps/
    ├── base/                # Base kustomization
    └── production/          # Production overlays

Deploying Applications with Flux

Define a Git Source

# infrastructure/sources/podinfo.yaml
apiVersion: source.toolkit.fluxcd.io/v1
kind: GitRepository
metadata:
  name: podinfo
  namespace: flux-system
spec:
  interval: 1m0s
  ref:
    branch: master
  url: https://github.com/stefanprodan/podinfo

Create a Kustomization

# apps/base/podinfo/kustomization.yaml
apiVersion: kustomize.toolkit.fluxcd.io/v1
kind: Kustomization
metadata:
  name: podinfo
  namespace: flux-system
spec:
  interval: 5m0s
  path: "./kustomize"
  prune: true
  sourceRef:
    kind: GitRepository
    name: podinfo
  targetNamespace: default
  healthChecks:
    - apiVersion: apps/v1
      kind: Deployment
      name: podinfo
      namespace: default

Helm Releases with Flux

Flux also supports Helm for more complex deployments:

# infrastructure/monitoring/kube-prometheus-stack.yaml
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: HelmRepository
metadata:
  name: prometheus-community
  namespace: flux-system
spec:
  interval: 1h
  url: https://prometheus-community.github.io/helm-charts
---
apiVersion: helm.toolkit.fluxcd.io/v2beta1
kind: HelmRelease
metadata:
  name: kube-prometheus-stack
  namespace: monitoring
spec:
  interval: 1h
  chart:
    spec:
      chart: kube-prometheus-stack
      version: ">= 55.0.0 < 56.0.0"
      sourceRef:
        kind: HelmRepository
        name: prometheus-community
        namespace: flux-system
  values:
    grafana:
      enabled: true
      adminPassword: ${GRAFANA_PASSWORD}
    prometheus:
      prometheusSpec:
        retention: 30d

Automated Image Updates

One of Flux’s powerful features is automated image updates:

apiVersion: image.toolkit.fluxcd.io/v1beta2
kind: ImageRepository
metadata:
  name: myapp
  namespace: flux-system
spec:
  image: myregistry.azurecr.io/myapp
  interval: 1m0s
---
apiVersion: image.toolkit.fluxcd.io/v1beta2
kind: ImagePolicy
metadata:
  name: myapp
  namespace: flux-system
spec:
  imageRepositoryRef:
    name: myapp
  policy:
    semver:
      range: ">=1.0.0 <2.0.0"

Monitoring Flux

Check the status of all Flux components:

# Check all Flux resources
flux get all --all-namespaces

# Watch for reconciliation events
flux get kustomizations --watch

# Get detailed logs
flux logs --all-namespaces --level=error

Conclusion

GitOps with Flux CD transforms how you manage Kubernetes clusters. By using Git as the single source of truth, you gain audit trails, easy rollbacks, and consistent environments across your infrastructure. Combined with AKS, it provides a robust foundation for enterprise Kubernetes operations.