Template for deploying a Kubernetes cluster backed by Flux

Welcome to my highly opinionated template for deploying a single Kubernetes (k3s) cluster with Ansible and managing applications with Flux. Upon completion you will be able to expose web applications you choose to the internet with Cloudflare Tunnel.

👋 Introduction

The following components will be installed in your k3s cluster by default. Most are only included to get a minimum viable cluster up and running.

• flux - GitOps operator for managing Kubernetes clusters from a Git repository
• kube-vip - Load balancer for the Kubernetes control plane nodes
• cert-manager - Operator to request SSL certificates and store them as Kubernetes resources
• cilium - Container networking interface for inter pod and service networking
• external-dns - Operator to publish DNS records to Cloudflare (and other providers) based on Kubernetes ingresses
• k8s_gateway - DNS resolver that provides local DNS to your Kubernetes ingresses
• ingress-nginx - Kubernetes ingress controller used for a HTTP reverse proxy of Kubernetes ingresses
• local-path-provisioner - provision persistent local storage with Kubernetes

Additional applications can be enabled in the addons configuration file

📝 Pre-start checklist

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

• Bring a positive attitude and be ready to learn and fail a lot. The more you fail, the more you can learn from.
• This was designed to run in your home network on bare metal machines or VMs NOT in the cloud.
• You MUST have a domain you can manage on Cloudflare.
• Secrets will be commited to your Git repository AND they will be encrypted by SOPS.
• Your domain name will NOT be visible to the public.
• You MUST have a DNS server that supports split DNS (e.g. Pi-Hole) deployed somewhere outside your cluster ON your home network.
• You have to use nodes that have access to the internet. This is not going to work in air-gapped environments.
• Only amd64 and/or arm64 nodes are supported.

With that out of the way please continue on if you are still interested...

💻 System Preparation

This projects supported Linux distro for running Kubernetes is Debian, Ubuntu might work but it is not currently supported due to these reasons.

Debian for AMD64

📍 Download the latest stable release of Debian from here

There is a decent guide here on how to get Debian installed.

1. Deviations from that guide

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

2. [Post install] Remove CD/DVD as apt source

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

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

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

4. [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 curl
   curl https://github.com/${github_username}.keys > ~/.ssh/authorized_keys
   chmod 600 ~/.ssh/authorized_keys

Debian for RasPi4

📍 Download the latest stable release of Debian from here. Do not use Raspbian.

If you choose to use a RasPi4 for the cluster, it is recommended to have a 8GB model (4GB minimum). Most important is to boot from an external SSD/NVMe, rather than the SD card. This is supported natively, however if you have an early RasPi4, you may need to update the bootloader.

According to the documentation here, after you have flashed the image onto a SSD/NVMe you must mount the drive and do the following.

1. Edit sysconf.txt
2. Change root_authorized_key to your desired public SSH key.
3. Change root_pw to your desired root password.
4. Change hostname to your desired hostname.

🚀 First Steps

The very first step will be to create a new public repository by clicking the big green Use this template button on this page. Next clone your new repo to you local workstation and cd into it.

📍 All of the below commands are run on your local workstation, not on any of your cluster nodes.

🔧 Workstation Tools

📍 Install the most recent version of the CLI tools below. If you are having trouble with future steps, it is very likely you don't have the most recent version of these CLI tools. The most troublesome are ansible, go-task, and sops.

1. Install the following CLI tools on your workstation, if you are using Homebrew skip this step and move onto 2 & 3.

   • Required: age, ansible, flux, cloudflared, go-task, direnv, kubectl, python3, python-pip3, sops

   • Recommended: helm, kustomize, stern

2. [Homebrew] Install go-task

   brew install go-task/tap/go-task

3. [Homebrew] Install the other workstation dependencies

   task brew:deps

🌱 Environment

Take a moment and configure direnv. This tool will make it so anytime you cd to your repo's directory it export the required environment variables (e.g. KUBECONFIG). To set this up make sure you hook it into your shell and after that is done, run direnv allow while in your repos directory.

📄 Configuration

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

1. Generate the bootstrap/vars/config.yaml and bootstrap/vars/addons.yaml configuration files.

   task init

2. 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

   age-keygen -o age.agekey

   2b. Create the directory for the Age key and move the Age file to it

   mkdir -p ~/.config/sops/age
   mv age.agekey ~/.config/sops/age/keys.txt

   2c. Fill out the appropriate vars in bootstrap/vars/config.yaml

3. 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

4. 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

5. Complete filling out the rest of the bootstrap/vars/config.yaml configuration file.

   5a. [Optional] Update bootstrap/vars/addons.yaml and enable applications you would like included.

6. 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

⚡ Node Preparation

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

1. 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 is how Ansible is able to connect to your remote nodes.

2. Install the Ansible deps

   task ansible:deps

3. Verify Ansible can view your config

   task ansible:list

4. Verify Ansible can ping your nodes

   task ansible:ping

5. Run the Ansible prepare playbook (nodes wil reboot when done)

   task ansible:prepare

---

⛵ Kubernetes Installation

📍 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.

1. Verify Ansible can view your config

   task ansible:list

2. Verify Ansible can ping your nodes

   task ansible:ping

3. Install k3s with Ansible

   task ansible:install

4. 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

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

🔹 GitOps with Flux

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

1. 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

2. 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

3. 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
   # ...

4. 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 🎄

1. 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

2. ⚠️ It might take cert-manager awhile to generate certificates, this is normal so be patient.

3. 🏆 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.

4. 🧠 Now it's time to pause and go get some motel motor oil ☕ and admire you made it this far!

📣 Post installation

🌐 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 public sub-domains exposed. In order to make additional applications public you must set an ingress annotation (external-dns.alpha.kubernetes.io/target) like done in the HelmRelease for echo-server.

For split DNS to work it is required to have ${bootstrap_cloudflare_domain} point to the ${bootstrap_k8s_gateway_addr} load balancer IP address on your home DNS server. This will ensure DNS requests for ${bootstrap_cloudflare_domain} will only get routed to your k8s_gateway service thus providing internal DNS resolution to your cluster applications/ingresses from any device that uses your home DNS server.

For and example with Pi-Hole apply the following file and restart dnsmasq:

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

Now try to resolve an internal-only domain with dig @${pi-hole-ip} hajimari.${bootstrap_cloudflare_domain} it should resolve to your ${bootstrap_ingress_nginx_addr} IP.

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 with the Let's Encrypt staging environment. This is to prevent you from getting rate-limited on configuration that might not be valid on bootstrap using the production server. If you had bootstrap_acme_production_enabled set to false in your config.yaml, make sure to switch to the Let's Encrypt production servers as outlined in that file. Do not enable the production certificate until you are sure you will keep the cluster up for more than a few hours.

🪝 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.

1. 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}'

2. Piece together the full URL with the webhook path appended

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

3. 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.

🤖 Renovatebot

Renovatebot will scan your repository and offer PRs when it finds dependencies out of date. Common dependencies it will discover and update are Flux, Ansible Galaxy Roles, Terraform Providers, Kubernetes Helm Charts, Kubernetes Container Images, and more!

The base Renovate configuration provided in your repository can be view at .github/renovate.json5. If you notice this only runs on weekends and you can change the schedule to anything you want or simply remove it.

To enable Renovate on your repository, click the 'Configure' button over at their Github app page and choose your repository. Renovate will create PRs for out-of-date dependencies it finds and when merged Flux will apply them to your cluster.

🐛 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.

1. 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

2. Then check all the Flux Helm Releases and verify they are healthy.

   flux get hr -A

3. Then check the if the pod is present.

   kubectl -n <namespace> get pods -o wide

4. Then check the logs of the pod if its there.

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

5. If a resource exists try to describe it to see what problems it might have.

   kubectl -n <namespace> describe <resource> <name>

6. Check the namespace events

   kubectl get events -n <namespace> --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 k8s@home 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

1. Generate new SSH key:

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

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

3. 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 ...

4. Encrypt secret:

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

5. Apply secret to cluster:

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

6. 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

7. Commit and push changes

8. Force flux to reconcile your changes

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

9. Verify git repository is now using SSH:

   flux get sources git -A

10. 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.