Homelab cluster with k3s and Flux

This repo configures a single Kubernetes (k3s) cluster with Ansible and uses the GitOps tool Flux to manage its state.

✨ Features

• Automated, reproducible, customizable setup through Ansible templates and playbooks
• Opinionated implementation of Flux from the Home Operations Community's template
• Encrypted secrets with SOPS and Age
• Web application firewall provided by Cloudflare Tunnels
• SSL certificates from Cloudflare and cert-manager
• HA control plane capability via kube-vip
• Next-gen networking using Cilium
• A Renovate-ready repository with pull request diffs provided by flux-local
• Integrated GitHub Actions

... and more!

📝 Prerequisites

• a domain managed on Cloudflare.
• a DNS server that supports split DNS (e.g. Pi-Hole) deployed somewhere outside your cluster ON your home network.

🚀 Installation

📍 Set up your local environment

1. Install task.

2. Install direnv.

3. Install pipx, then ensure hooks are set with:

   pipx ensurepath
   pipx completions

4. Finish configuring the workstation.
   Conveniently, we can use a task that has been defined for this!

   task workstation:setup

   This command will install ansible in a pipx environment, then use brew to install other necessary binaries like age, flux, cloudflared, kubectl, and sops

🔧 Initial configuration

1. Setup Age private / public key

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

   a. Create an Age private / public key (this file is gitignored)

   age-keygen -o age.key

   b. Ensure that this key is available as an environment variable.

   Add the following to the .envrc:

   # export SOPS_AGE_KEY_FILE="$(expand_path "${HOME}/Library/Application Support/sops/age/keys.txt")"
   export SOPS_AGE_KEY_FILE="$(expand_path "${HOME}/.config/sops/age/keys.txt")"
   export AGE_PUBLIC_KEY="$(grep "public key" "$SOPS_AGE_KEY_FILE" | awk '{ print $4 }')"

   Then run direnv allow . to refresh the environment.

2. Create Cloudflare API Token

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

   a. Create a Cloudflare API Token by going here.

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

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

   d. Name your token something like home-kubernetes

   e. Under Permissions, click + Add More and add each permission below:

   Zone - DNS - Edit
   Account - Cloudflare Tunnel - Read
   

   f. Limit the permissions to a specific account and zone resources.

   g. Fill out the appropriate vars in .env file:

   CLOUDFLARE_EMAIL=''
   CLOUDFLARE_TOKEN=''
   CLOUDFLARE_ACCOUNT=''
   CLOUDFLARE_TUNNELID=''
   CLOUDFLARE_TUNNEL_SECRET=''

3. Create Cloudflare Tunnel

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

   a. Authenticate cloudflared to your domain

   cloudflared tunnel login

   b. Create the tunnel

   cloudflared tunnel create k8s

   c. Fill out the appropriate Cloudflare Tunnel vars in .env file: CLOUDFLARE_ACCOUNT, CLOUDFLARE_TUNNELID, CLOUDFLARE_TUNNEL_SECRET

   Cloudflare Tunnel info can be found with cat ~/.cloudflared/*.json | jq -r

⚡ Prepare your nodes for k3s

📍 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 lets Ansible interact with your nodes.

2. Verify Ansible can view your config

   task ansible:hosts

3. Verify Ansible can ping your nodes

   task ansible:ping

4. Run the Ansible prepare playbook (nodes will reboot when done)

   task ansible:prepare

🛰️ Build your k3s cluster with Ansible

📍 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 k3s:nuke to destroy the k3s cluster and start over from this point.

1. Verify Ansible can view your config

   task ansible:hosts

2. Verify Ansible can ping your nodes

   task ansible:ping

3. Install k3s (may need to run this twice to pass the k3s systemd restart)

   task k3s:install

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

4. Verify the nodes are online

   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. Review the pods currently running in the cluster

   kubectl get pods -A -o wide

🔹 Install Flux in your cluster

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 flux:bootstrap
   # 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

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 k8s:resources

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

📣 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).

Tip

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

1. Apply this file on the server

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

2. Restart dnsmasq on the server.

3. 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.

1. Follow FluxCD instructions to generate a token.

2. 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}'

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

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

4. 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.

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 -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.

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 ... -----
           ...
       -----END OPENSSH ... -----
     # 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

This would not be possible without onedr0p and the k8s-at-home community!