> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.

# FluxCD Concepts amp Terminology

> This article provides an overview of FluxCDs core components and GitOps terminology.

<Callout icon="lightbulb" color="#1CB2FE">
  This guide assumes you're familiar with [GitOps](https://www.gitops.tech/), [Docker](https://www.docker.com/), [Kubernetes](https://kubernetes.io/), and CI/CD workflows.
</Callout>

## Key Concepts Overview

Below is a quick reference of FluxCD’s core components and GitOps terminology.

| Concept            | Controller / Command                               | Purpose                                                     |
| ------------------ | -------------------------------------------------- | ----------------------------------------------------------- |
| Bootstrapping      | `flux bootstrap`                                   | Installs Flux controllers and Git repository sources.       |
| Agent / Controller | Reconciliation loops                               | Watches CRDs and aligns cluster state with Git definitions. |
| Source             | `GitRepository`, `HelmRepository`, `OCIRepository` | Fetches and tracks external repositories.                   |
| Kustomization      | `Kustomization`                                    | Applies and reconciles overlays or plain manifests.         |
| Reconciliation     | Continuous process                                 | Ensures actual cluster state matches Git’s desired state.   |
| Suspend & Resume   | `flux suspend` / `flux resume`                     | Pauses or restarts automatic reconciliation.                |
| Prune              | Automatic cleanup                                  | Removes resources no longer defined in the source.          |
| Image Automation   | `flux image`                                       | Updates Git when new container images are available.        |

## 1. Bootstrapping

Bootstrapping is the initial step to install Flux components on your Kubernetes cluster.\
Use the `flux bootstrap` command to connect your cluster with a Git repository following GitOps best practices.

## 2. Agent / Controller

Flux controllers (or agents) implement Kubernetes’ controller pattern:

* They run *reconciliation loops*.
* Watch for custom resources (CRDs).
* Continuously compare and reconcile the cluster’s actual state against Git-defined desired state.

## 3. Sources

Sources define where Flux retrieves configuration or package artifacts:

* **GitRepository**: Monitors a Git repo for YAML manifests or Kustomize overlays.
* **HelmRepository**: Tracks Helm charts.
* **OCIRepository**: Fetches Helm charts or container images from an OCI registry.

## 4. Kustomization

The Kustomization controller applies a set of overlays or plain manifests:

* Applies resources to the cluster.
* Continuously reconciles updates.
* Supports features like patches, generators, and strategic merges.

## 5. Reconciliation

Reconciliation is Flux’s core mechanism:

* Compares the *actual* state of your cluster with the *desired* state defined in Git.
* By default, reconciliation runs automatically at each interval.
* You can temporarily suspend or resume this process.

<Callout icon="triangle-alert" color="#FF6B6B">
  Suspending reconciliation in production may delay critical updates. Always verify before pausing.
</Callout>

## 6. Suspend & Resume

Use the Flux CLI to manage reconciliation:

```bash theme={null}
flux suspend kustomization webapp
flux resume kustomization webapp
```

When suspended, manual intervention via `flux reconcile` is required to apply changes.

## 7. Prune

Pruning ensures your cluster stays clean:

* When enabled, Flux automatically deletes Kubernetes resources that are no longer defined in the Git source.
* Helps prevent resource drift and orphaned objects.

<Frame>
  ![The image is a table explaining FluxCD concepts and terminology, including terms like Bootstrap, Agent, Controller, Sources, Kustomization, Reconciliation, Suspend, Resume, Prune, and Image. It includes brief definitions for each term.](https://kodekloud.com/kk-media/image/upload/v1752877614/notes-assets/images/GitOps-with-FluxCD-FluxCD-Concepts-amp-Terminology/fluxcd-concepts-terminology-table.jpg)
</Frame>

## 8. Flux Image Automation

The `flux image` command manages image automation objects:

* **Image Reflector Controller**: Monitors container registries for new tags.
* **Image Automation Controller**: Commits updated image references to your Git repository.

### Common Commands

```bash theme={null}
# Watch for new images in a registry
flux create image repository my-app \
  --image=myregistry/my-app \
  --interval=1m

# Automate Git updates when a new image is available
flux create image automation my-app \
  --image-ref=ImageRepository/my-app \
  --update-path="./deploy" \
  --interval=5m
```

***

## References

* [FluxCD Documentation](https://fluxcd.io/docs/)
* [GitOps with Flux](https://github.com/fluxcd/flux2)
* [Kubernetes Controllers](https://kubernetes.io/docs/concepts/architecture/controller/)
* [Helm Charts in Flux](https://fluxcd.io/docs/components/helm/)

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