Skip to main content

Flux CD Workflows

Updated Aug 19, 2022 ·

Overview​

Flux CD helps manage Kubernetes using Git as the single source of truth. It follows a GitOps model to keep your system up to date automatically.

  • Uses Git to store your desired system state
  • You don't manually apply updates
  • Updates your cluster when Git change
  • Automates keeping workloads up to date

Stages In Flux CD​

Flux CD works in a loop with three key stages: source control, synchronization, and reconciliation.

  • Source Control
  • Synchronization
  • Reconciliation

Stage 1: Source Control​

Flux CD starts by checking Git for updates to your Kubernetes files.

  • Detects any file change like image tags or service settings
  • Uses the source controller to fetch updates regularly

Flux CD looks at this GitRepository object and pulls updates every minute.

apiVersion: source.toolkit.fluxcd.io/v1
kind: GitRepository
metadata:
  name: my-git-repo
spec:
  interval: 1m
  url: https://github.com/example-org/my-k8s-configs
  branch: main

Stage 2: Synchronization​

Once changes are fetched from Git, they are stored as Kubernetes objects inside the cluster.

This avoids frequent Git calls and keeps the desired state easily accessible.

apiVersion: kustomize.toolkit.fluxcd.io/v1
kind: Kustomization
metadata:
  name: my-app
spec:
  interval: 5m
  path: "./apps/my-app"
  prune: true
  sourceRef:
    kind: GitRepository
    name: my-git-repo

This tells Flux where in the Git repo the config lives and how often to sync.

Stage 3: Reconciliation​

Flux CD then makes the actual changes to the cluster to match what’s in Git.

  • Compares current cluster state with desired Git state
  • Updates, deletes, or creates resources to match Git

Controllers like Kustomize or Helm apply these changes.

apiVersion: helm.toolkit.fluxcd.io/v2beta1
kind: HelmRelease
metadata:
  name: my-helm-app
spec:
  chart:
    spec:
      chart: mychart
      version: "1.2.3"
  interval: 5m
  values:
    replicaCount: 2

If the chart or values change in Git, Flux updates your app accordingly.

Use Helm with Flux CD​

You can also manage Helm apps declaratively with Flux CD.

  • Use HelmRelease CRD in your Git repo
  • Define your chart, version, and values
  • Flux reads and installs it for you

Here’s an example:

apiVersion: helm.toolkit.fluxcd.io/v2beta1
kind: HelmRelease
metadata:
  name: my-app
spec:
  chart:
    spec:
      chart: nginx
      version: "9.0.1"
      sourceRef:
        kind: HelmRepository
        name: bitnami
  interval: 5m
  values:
    replicaCount: 2

Flux will install the chart and keep it in sync with the values in your Git file.

Customize for different environments​

You can handle dev, test, and prod using Kustomize overlays.

  • Write a base config once
  • Add overlays for each environment
  • Use the Kustomize controller to apply the right one

This helps you reuse files and only change what's different in each environment.

Automate Image Updates​

Flux CD can also update workloads automatically when a new Docker image is available.

  • Checks image tags in your container registry
  • Updates Git with the new tag
  • Applies the updated manifest automatically

This removes the need to manually edit image tags.

apiVersion: image.toolkit.fluxcd.io/v1beta1
kind: ImageRepository
metadata:
  name: myapp
spec:
  image: myregistry.com/myapp
  interval: 1m
apiVersion: image.toolkit.fluxcd.io/v1beta1
kind: ImageUpdateAutomation
metadata:
  name: myapp-automation
spec:
  sourceRef:
    kind: GitRepository
    name: my-git-repo
  update:
    strategy: Setters

Whenever a new image tag is pushed, Flux updates Git and your app.