Deploy a Kubernetes cluster backed by Flux

Welcome to my highly opinionated template for deploying a single Kubernetes (k3s) cluster with Ansible and using Flux to manage its state.

👋 Introduction

The goal of this project is to make it easy for people interested in learning Kubernetes to deploy a cluster at home and become familiar with the GitOps tool Flux.

This template implements Flux in a way that promotes legibility and ease of use for those who are new (or relatively new) to the technology and GitOps in general.

✨ Features

Automated, reproducible, customizable setup through Ansible templates and playbooks
Opinionated implementation of Flux with strong community support
Encrypted secrets thanks to SOPS and Age
Web application firewall thanks to Cloudflare Tunnels
SSL certificates thanks to Cloudflare and cert-manager
HA control plane capability thanks to kube-vip
Next-gen networking thanks to Cilium
A Renovate-ready repository with pull request diffs provided by flux-local
Integrated GitHub Actions

... and more!

📝 Pre-start checklist

Before we get started everything below must be taken into consideration, you must...

have some experience with the following: Git/SCM, containers, networking and scripting.
bring a positive attitude and be ready to learn and fail a lot. The more you fail, the more you can learn from.
run the cluster on bare metal machines or VMs within your home network — this is NOT designed for cloud environments.
have Debian 12 freshly installed on 1 or more AMD64/ARM64 bare metal machines or VMs. Each machine will be either a control node or a worker node in your cluster.
give your nodes unrestricted internet access — air-gapped environments won't work.
have a domain you can manage on Cloudflare.
be willing to commit encrypted secrets to a public GitHub repository.
have a DNS server that supports split DNS (e.g. Pi-Hole) deployed somewhere outside your cluster ON your home network.

💻 Machine Preparation

System requirements

📍 k3s default behaviour is that all nodes are able to run workloads, including contol nodes. Worker nodes are therefore optional.

📍 If you have 3 or more nodes it is strongly recommended to make 3 of them control nodes for a highly available control plane.

📍 Ideally you will run the cluster on bare metal machines. If you intend to run your cluster on Proxmox VE, my thoughts and recommendations about that are documented here.

Role	Cores	Memory	System Disk
Control	4 (6)*	8GB (24GB)*	100GB (500GB)* SSD/NVMe
Worker	4 (6)*	8GB (24GB)*	100GB (500GB)* SSD/NVMe
* recommended

Debian for AMD64

Download the latest stable release of Debian from here, then follow this guide to get it installed. Deviations from the guide:

Choose "Guided - use entire disk"
Choose "All files in one partition"
Delete Swap partition
Uncheck all Debian desktop environment options

[Post install] Remove CD/DVD as apt source

su -
sed -i '/deb cdrom/d' /etc/apt/sources.list
apt update
exit

[Post install] Enable sudo for your non-root user

su -
apt update
apt install -y sudo
usermod -aG sudo ${username}
echo "${username} ALL=(ALL) NOPASSWD:ALL" | tee /etc/sudoers.d/${username}
exit
newgrp sudo
sudo apt update

[Post install] Add SSH keys (or use ssh-copy-id on the client that is connecting)

📍 First make sure your ssh keys are up-to-date and added to your github account as instructed.
```
mkdir -m 700 ~/.ssh
sudo apt install -y curl
curl https://github.com/${github_username}.keys > ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys
```

Debian for RasPi4

📍 If you choose to use a Raspberry Pi 4 for the cluster, it is recommended to have an 8GB model. Most important is to boot from an external SSD/NVMe rather than an SD card. This is supported natively, however if you have an early model you may need to update the bootloader first.

📍 Be sure to check the power requirements if using a PoE Hat and a SSD/NVMe dongle.

Download the latest stable release of Debian from here. Do not use Raspbian or DietPi or any other flavor Linux OS.
Flash the image onto an SSD/NVMe drive.

Re-mount the drive to your workstation and then do the following (per the official documentation):

Open 'sysconf.txt' in a text editor and save it upon updating the information below
  - Change 'root_authorized_key' to your desired public SSH key
  - Change 'root_pw' to your desired root password
  - Change 'hostname' to your desired hostname

Connect SSD/NVMe drive to the Raspberry Pi 4 and power it on.
[Post install] SSH into the device with the root user and then create a normal user account with adduser ${username}
[Post install] Follow steps 3 and 4 from Debian for AMD64.
[Post install] Install python3 which is needed by Ansible.
```
sudo apt install -y python3
```

🚀 Getting Started

Once you have installed Debian on your nodes, there are six stages to getting a Flux-managed cluster up and runnning.

📍 For all stages below the commands MUST be ran on your personal workstation within your repository directory

🎉 Stage 1: Create a Git repository

Create a new public repository by clicking the big green "Use this template" button at the top of this page.
Clone your new repo to you local workstation and cd into it.

🌱 Stage 2: Setup your local workstation environment

📍 Let's get the required workstation tools installed and configured.

Install the most recent version of task

📍 See the task installation docs for other platforms
```
# Brew
brew install go-task
```
Install the most recent version of direnv

📍 See the direnv installation docs for other platforms

📍 After installing direnv be sure to hook it into your shell and after that is done run direnv allow while in your repos directory.
```
# Brew
brew install direnv
```
Setup a Python virual env and install Ansible by running the following task command.

📍 This commands requires Python 3.10+ to be installed
```
# Platform agnostic
task deps
```
Install the required tools: age, flux, cloudflared, kubectl, sops
```
# Brew
task brew:deps
```

🔧 Stage 3: Do bootstrap configuration

📍 Both bootstrap/vars/config.yaml and bootstrap/vars/addons.yaml files contain necessary information that is needed by bootstrap process.

Generate the bootstrap/vars/config.yaml and bootstrap/vars/addons.yaml configuration files.
```
task init
```
Setup Age private / public key

📍 Using SOPS with Age allows us to encrypt secrets and use them in Ansible and Flux.

2a. Create a Age private / public key (this file is gitignored)
```
age-keygen -o age.key
```
2b. Fill out the appropriate vars in bootstrap/vars/config.yaml
Create Cloudflare API Token

📍 To use cert-manager with the Cloudflare DNS challenge you will need to create a API Token.

3a. Head over to Cloudflare and create a API Token by going here.

3b. Under the API Tokens section click the blue Create Token button.

3c. Click the blue Use template button for the Edit zone DNS template.

3d. Name your token something like home-kubernetes

3e. Under Permissions, click + Add More and add each permission below:
```
Zone - DNS - Edit
Account - Cloudflare Tunnel - Read
```
3f. Limit the permissions to a specific account and zone resources.

3g. Fill out the appropriate vars in bootstrap/vars/config.yaml
Create Cloudflare Tunnel

📍 To expose services to the internet you will need to create a Cloudflare Tunnel.

4a. Authenticate cloudflared to your domain
```
cloudflared tunnel login
```
4b. Create the tunnel
```
cloudflared tunnel create k8s
```
4c. In the ~/.cloudflared directory there will be a json file with details you need. Ignore the cert.pem file.

4d. Fill out the appropriate vars in bootstrap/vars/config.yaml
Complete filling out the rest of the bootstrap/vars/config.yaml configuration file.

5a. Ensure bootstrap_acme_production_enabled is set to false.

5b. [Optional] Update bootstrap/vars/addons.yaml and enable applications you would like included.
Once done run the following command which will verify and generate all the files needed to continue.
```
task configure
```

📍 The configure task will create a ./ansible directory and the following directories under ./kubernetes.

📁 kubernetes      # Kubernetes cluster defined as code
├─📁 bootstrap     # Flux installation (not tracked by Flux)
├─📁 flux          # Main Flux configuration of repository
└─📁 apps          # Apps deployed into the cluster grouped by namespace

⚡ Stage 4: Prepare your nodes for k3s

📍 Here we will be running an Ansible playbook to prepare your nodes for running a Kubernetes cluster.

Ensure you are able to SSH into your nodes from your workstation using a private SSH key without a passphrase (for example using a SSH agent). This lets Ansible interact with your nodes.
Verify Ansible can view your config
```
task ansible:list
```
Verify Ansible can ping your nodes
```
task ansible:ping
```
Run the Ansible prepare playbook (nodes wil reboot when done)
```
task ansible:prepare
```

⛵ Stage 5: Use Ansible to install k3s

📍 Here we will be running a Ansible Playbook to install k3s with this Ansible galaxy role. If you run into problems, you can run task ansible:nuke to destroy the k3s cluster and start over from this point.

Verify Ansible can view your config
```
task ansible:list
```
Verify Ansible can ping your nodes
```
task ansible:ping
```
Install k3s with Ansible
```
task ansible:install
```

Verify the nodes are online

📍 If this command fails you likely haven't configured direnv as mentioned previously in the guide.

kubectl get nodes -o wide
# NAME           STATUS   ROLES                       AGE     VERSION
# k8s-0          Ready    control-plane,etcd,master   1h      v1.27.3+k3s1
# k8s-1          Ready    worker                      1h      v1.27.3+k3s1

The kubeconfig for interacting with your cluster should have been created in the root of your repository.

🔹 Stage 6: Install Flux in your cluster

📍 Here we will be installing flux after some quick bootstrap steps.

Verify Flux can be installed

flux check --pre
# ► checking prerequisites
# ✔ kubectl 1.27.3 >=1.18.0-0
# ✔ Kubernetes 1.27.3+k3s1 >=1.16.0-0
# ✔ prerequisites checks passed

Push you changes to git

📍 Verify all the *.sops.yaml and *.sops.yaml files under the ./ansible, and ./kubernetes directories are encrypted with SOPS
```
git add -A
git commit -m "Initial commit :rocket:"
git push
```

Install Flux and sync the cluster to the Git repository

task cluster:install
# namespace/flux-system configured
# customresourcedefinition.apiextensions.k8s.io/alerts.notification.toolkit.fluxcd.io created
# ...

Verify Flux components are running in the cluster

kubectl -n flux-system get pods -o wide
# NAME                                       READY   STATUS    RESTARTS   AGE
# helm-controller-5bbd94c75-89sb4            1/1     Running   0          1h
# kustomize-controller-7b67b6b77d-nqc67      1/1     Running   0          1h
# notification-controller-7c46575844-k4bvr   1/1     Running   0          1h
# source-controller-7d6875bcb4-zqw9f         1/1     Running   0          1h

🎤 Verification Steps

Mic check, 1, 2 - In a few moments applications should be lighting up like Christmas in July 🎄

Output all the common resources in your cluster.

📍 Feel free to use the provided cluster tasks for validation of cluster resources or continue to get familiar with the kubectl and flux CLI tools.
```
task cluster:resources
```
⚠️ It might take cert-manager awhile to generate certificates, this is normal so be patient.
🏆 Congratulations if all goes smooth you will have a Kubernetes cluster managed by Flux and your Git repository is driving the state of your cluster.
🧠 Now it's time to pause and go get some motel motor oil ☕ and admire you made it this far!

📣 Post installation

🌐 Public DNS

The external-dns application created in the networking namespace will handle creating public DNS records. By default, echo-server and the flux-webhook are the only subdomains reachable from the public internet. In order to make additional applications public you must set set the correct ingress class name and ingress annotations like in the HelmRelease for echo-server.

🏠 Home DNS

k8s_gateway will provide DNS resolution to external Kubernetes resources (i.e. points of entry to the cluster) from any device that uses your home DNS server. For this to work, your home DNS server must be configured to forward DNS queries for ${bootstrap_cloudflare_domain} to ${bootstrap_k8s_gateway_addr} instead of the upstream DNS server(s) it normally uses. This is a form of split DNS (aka split-horizon DNS / conditional forwarding).

📍 Below is how to configure a Pi-hole for split DNS. Other platforms should be similar.

Apply this file on the server

# /etc/dnsmasq.d/99-k8s-gateway-forward.conf
server=/${bootstrap_cloudflare_domain}/${bootstrap_k8s_gateway_addr}

Restart dnsmasq on the server.
Query an internal-only subdomain from your workstation (any internal class ingresses): dig @${home-dns-server-ip} hubble.${bootstrap_cloudflare_domain}. It should resolve to ${bootstrap_internal_ingress_addr}.

If you're having trouble with DNS be sure to check out these two GitHub discussions: Internal DNS and Pod DNS resolution broken.

... Nothing working? That is expected, this is DNS after all!

📜 Certificates

By default this template will deploy a wildcard certificate using the Let's Encrypt staging environment, which prevents you from getting rate-limited by the Let's Encrypt production servers if your cluster doesn't deploy properly (for example due to a misconfiguration). Once you are sure you will keep the cluster up for more than a few hours be sure to switch to the production servers as outlined in config.yaml.

📍 You will need a production certificate to reach internet-exposed applications through cloudflared.

🪝 Github Webhook

By default Flux will periodically check your git repository for changes. In order to have Flux reconcile on git push you must configure Github to send push events.

Obtain the webhook path

📍 Hook id and path should look like /hook/12ebd1e363c641dc3c2e430ecf3cee2b3c7a5ac9e1234506f6f5f3ce1230e123
```
kubectl -n flux-system get receiver github-receiver -o jsonpath='{.status.webhookPath}'
```

Piece together the full URL with the webhook path appended

https://flux-webhook.${bootstrap_cloudflare_domain}/hook/12ebd1e363c641dc3c2e430ecf3cee2b3c7a5ac9e1234506f6f5f3ce1230e123

Navigate to the settings of your repository on Github, under "Settings/Webhooks" press the "Add webhook" button. Fill in the webhook url and your bootstrap_flux_github_webhook_token secret and save.

🤖 Renovate

Renovate is a tool that automates dependency management. It is designed to scan your repository around the clock and open PRs for out-of-date dependencies it finds. Common dependencies it can discover are Helm charts, container images, GitHub Actions, Ansible roles... even Flux itself! Merging a PR will cause Flux to apply the update to your cluster.

To enable Renovate, click the 'Configure' button over at their Github app page and select your repository. Renovate creates a "Dependency Dashboard" as an issue in your repository, giving an overview of the status of all updates. The dashboard has interactive checkboxes that let you do things like advance scheduling or reattempt update PRs you closed without merging.

The base Renovate configuration in your repository can be viewed at .github/renovate.json5. By default it is scheduled to be active with PRs every weekend, but you can change the schedule to anything you want, or remove it if you want Renovate to open PRs right away.

🐛 Debugging

Below is a general guide on trying to debug an issue with an resource or application. For example, if a workload/resource is not showing up or a pod has started but in a CrashLoopBackOff or Pending state.

Start by checking all Flux Kustomizations & Git Repository & OCI Repository and verify they are healthy.
```
flux get sources oci -A
flux get sources git -A
flux get ks -A
```
Then check all the Flux Helm Releases and verify they are healthy.
```
flux get hr -A
```
Then check the if the pod is present.
```
kubectl -n <namespace> get pods -o wide
```

Then check the logs of the pod if its there.

kubectl -n <namespace> logs <pod-name> -f
# or
stern -n <namespace> <fuzzy-name>

If a resource exists try to describe it to see what problems it might have.
```
kubectl -n <namespace> describe <resource> <name>
```

Check the namespace events

kubectl -n <namespace> get events --sort-by='.metadata.creationTimestamp'

Resolving problems that you have could take some tweaking of your YAML manifests in order to get things working, other times it could be a external factor like permissions on NFS. If you are unable to figure out your problem see the help section below.

👉 Help

Make a post in this repository's Github Discussions.
Start a thread in the support or flux-cluster-template channel in the Home Operations Discord server.

❔ What's next

The cluster is your oyster (or something like that). Below are some optional considerations you might want to review.

Ship it

To browse or get ideas on applications people are running, community member @whazor created this website as a creative way to search Flux HelmReleases across Github.

Storage

The included CSI (local-path-provisioner) is a great start for storage but soon you might find you need more features like replicated block storage, or to connect to a NFS/SMB/iSCSI server. If you need any of those features be sure to check out the projects like rook-ceph, longhorn, openebs, democratic-csi, csi-driver-nfs, and synology-csi.

Authenticate Flux over SSH

Authenticating Flux to your git repository has a couple benefits like using a private git repository and/or using the Flux Image Automation Controllers.

By default this template only works on a public Github repository, it is advised to keep your repository public.

The benefits of a public repository include:

Debugging or asking for help, you can provide a link to a resource you are having issues with.
Adding a topic to your repository of k8s-at-home to be included in the k8s-at-home-search. This search helps people discover different configurations of Helm charts across others Flux based repositories.

Expand to read guide on adding Flux SSH authentication

Generate new SSH key:

ssh-keygen -t ecdsa -b 521 -C "github-deploy-key" -f ./kubernetes/bootstrap/github-deploy.key -q -P ""

Paste public key in the deploy keys section of your repository settings

Create sops secret in ./kubernetes/bootstrap/github-deploy-key.sops.yaml with the contents of:

apiVersion: v1
kind: Secret
metadata:
  name: github-deploy-key
  namespace: flux-system
stringData:
  # 3a. Contents of github-deploy-key
  identity: |
    -----BEGIN OPENSSH PRIVATE KEY-----
        ...
    -----END OPENSSH PRIVATE KEY-----
  # 3b. Output of curl --silent https://api.github.com/meta | jq --raw-output '"github.com "+.ssh_keys[]'
  known_hosts: |
    github.com ssh-ed25519 ...
    github.com ecdsa-sha2-nistp256 ...
    github.com ssh-rsa ...

Encrypt secret:

sops --encrypt --in-place ./kubernetes/bootstrap/github-deploy-key.sops.yaml

Apply secret to cluster:

sops --decrypt ./kubernetes/bootstrap/github-deploy-key.sops.yaml | kubectl apply -f -

Update ./kubernetes/flux/config/cluster.yaml:

apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: GitRepository
metadata:
  name: home-kubernetes
  namespace: flux-system
spec:
  interval: 10m
  # 6a: Change this to your user and repo names
  url: ssh://git@github.com/$user/$repo
  ref:
    branch: main
  secretRef:
    name: github-deploy-key

Commit and push changes

Force flux to reconcile your changes

flux reconcile -n flux-system kustomization cluster --with-source

Verify git repository is now using SSH:
```
flux get sources git -A
```
Optionally set your repository to Private in your repository settings.

🤝 Thanks

Big shout out to all the contributors, sponsors and everyone else who has helped on this project.

johnnymiranda/flux-cluster