How to implement GitOps with Flux

What and why

Flux is a GitOps toolkit for Kubernetes. It watches Git sources and applies their manifests to the cluster on a schedule, keeping the cluster aligned with Git. Unlike a UI-first tool, Flux is configured entirely through Kubernetes custom resources. This tutorial bootstraps Flux and reconciles an app.

Prerequisites

• A Kubernetes cluster and kubectl access.
• A Git provider repo plus a personal access token with repo scope.
• The flux CLI installed.

Steps

1. Install the flux CLI

Install the CLI and confirm:

flux --version

2. Run the pre-flight check

flux check --pre

This verifies your cluster version and permissions before installing anything.

3. Bootstrap Flux

flux bootstrap github \
  --owner=acme \
  --repository=fleet \
  --path=clusters/prod \
  --personal

Bootstrap installs Flux controllers and commits its own config into your repo, so Flux manages itself via GitOps.

4. Define a GitRepository source

apiVersion: source.toolkit.fluxcd.io/v1
kind: GitRepository
metadata:
  name: app
  namespace: flux-system
spec:
  interval: 1m
  url: https://github.com/acme/app
  ref:
    branch: main

A source tells Flux where to fetch manifests and how often.

5. Add a Kustomization

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

The Kustomization applies a path from the source and prunes removed resources.

Verification

Run flux get kustomizations. The app should show Ready: True. Push a change to the manifest path and run flux reconcile kustomization app; the change appears in the cluster, confirming the loop works.

Next Steps

Add image automation to bump tags from a registry. Use SOPS to encrypt secrets in Git. Separate environments by path or repository to control blast radius.