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Starter Notes

Updated Aug 19, 2022 ·

Overview​

GitOps uses Git to manage and automate everything about your infrastructure and app deployments.

  • Git holds all the configuration
  • Everything is written in files
  • It keeps the real system in sync with the files

This means Git becomes the only place where you make changes, and your systems follow automatically.

  • Every change is tracked
  • Teams work better together
  • Deployments happen automatically

How Flux CD Helps​

Flux CD is a tool that keeps your Kubernetes apps in sync with your Git repository.

  • Uses Git to define how apps should run
  • Automatically updates your cluster
  • Works well with Kubernetes
  • Syncs your cluster to match your Git files
  • Supports multiple teams and clusters

Flux CD connects your Git repository to your Kubernetes cluster and keeps everything in sync.

Concepts​

  • Bootstrapping

    • Installs Flux components in the cluster
    • Follows GitOps practices for deployment

  • Agent

    • Process inside the cluster that performs tasks for the user
    • Supports automation through Flux controllers

  • Flux Controllers

    • Specialized agents following the Kubernetes controller pattern
    • Use control loops with custom resources to manage cluster state

  • Sources

    • Git, Helm, or OCI repositories containing the desired state
    • Define where Flux retrieves configuration from

  • Kustomization

    • Applies customized Kubernetes resources
    • Works with overlays or plain manifests

  • Reconciliation

    • Keeps cluster state in sync with Git automatically
    • Can be paused or resumed manually

  • Pruning

    • Removes outdated resources no longer in the source
    • Enabled when prune is set to true

  • Flux Image Automation

    • Uses controllers to detect new container images
    • Updates Git with the latest image versions

Good Practices with Flux CD​

To make GitOps work well, use these tips with Flux CD.

  • Keep files simple and clean
  • Always check Git pull requests before merging
  • Watch the sync status
  • Protect your Git repo with SSH or tokens

These habits help you stay secure, make fewer mistakes, and catch problems early.

Example Setup​

Here’s a basic example using Flux CD to watch a Kubernetes deployment file:

apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: GitRepository
metadata:
  name: my-app-config
  namespace: flux-system
spec:
  interval: 1m
  url: https://github.com/example-user/my-gitops-repo
  branch: main
apiVersion: kustomize.toolkit.fluxcd.io/v1beta2
kind: Kustomization
metadata:
  name: my-app
  namespace: flux-system
spec:
  interval: 5m
  path: ./deployments/my-app
  prune: true
  sourceRef:
    kind: GitRepository
    name: my-app-config

This tells Flux to pull the config from Git and apply it every few minutes.

Add-Ons in Flux CD​

Flux CD supports extra tools for more complex deployments.

  • Helm controller for using Helm charts
  • Kustomize controller for plain YAML configs

Managing Deployments​

Flux gives you tools to check what’s happening in your cluster.

  • Use CLI or dashboard to see status
  • Check for errors or issues
  • Track changes using Git history

This visibility helps you understand what changed, when, and why.