k3s Homelab

This repository serves as a 'live' repository for a k3s based homelab used for learning exercises with kubernetes and devops topics in general. The tools and technologies used include:

Infrastructure

• k3s - fairly simple way to get a kubernetes cluster with multiple nodes set up
• MetalLB - Loadbalancing for application access is something a cloud provider normally provides, but since this is using resources on my local network, MetalLB enables mapping local IP addresses directly to services running inside the cluster.
• Longhorn - enables fairly straightforward configuration of persistence options in the cluster. Manages persistent volumes and persistent volume claims and provides scheduled backups, and more importantly restoration of said backups.
• Bitnami Sealed Secrets - a 'good enough' utility that allows a declarative approach to secrets management.
• ArgoCD - Allows declarative management of tools as well as any applications deployed into the cluster.

Monitoring

• Grafana's LGTM stack - Not very lightweight, but provides a 'single pane of glass' view into all things observability related.

Applications

• Gitea - lightweight github clone, allows private, on prem hosting of git projects. A great exercise in deploying and maintaining an application that utilizes persistent storage with longhorn.

Break Glass / Initial Setup

k3s

1. Install k3s on the master node:

   curl -sfL https://get.k3s.io | sh -s - --write-kubeconfig-mode 644 --token <pw> --node-taint CriticalAddonsOnly=true:NoExecute --bind-address <public IP address> --disable=traefik --disable=servicelb

2. Get the kube config from the master to configure kubectl on another machine

   cat /etc/rancher/k3s/k3s.yaml

3. Install k3s on each node:

   curl -sfL https://get.k3s.io | K3S_URL=https://<master node IP address>:6443 K3S_TOKEN=<pw> sh -

4. (Optional) Label Nodes

   kubectl label nodes <node-name> kubernetes.io/role=worker
   kubectl label nodes <node-name> node-type=worker

MetalLB

1. Use kustomize to generate deployment yaml

   kubectl kustomize manifests/metallb >metallb-deployment.yaml

2. Review generated yaml for correctness.

3. Deploy into k3s:

   kubectl apply -f metallb-deployment.yaml

   With MetalLB controller deployed, we can now just deploy a kubernetes Service resource with the type of Loadbalancer and MetalLB will see to the service being mapped to an IP address from the defined pool.

Sealed Secrets Controller

kubectl kustomize --enable-helm manifests/tools/sealed-secrets > sealed-secrets-deployment.yaml
# Verify yaml contents
kubectl apply -f sealed-secrets-deployment.yaml

ArgoCD Bootstrap

This configuration is inspired by the ArgoCD docs themselves, particularly

• https://argo-cd.readthedocs.io/en/stable/operator-manual/declarative-setup/#manage-argo-cd-using-argo-cd
• https://argo-cd.readthedocs.io/en/stable/operator-manual/cluster-bootstrapping/

The tools group uses an ApplicationSet:

• https://argo-cd.readthedocs.io/en/stable/operator-manual/applicationset/

The overall idea is to have everything that runs in kubernetes declaratively managed by ArgoCD, including ArgoCD itself, which presents a chicken and the egg situation: How does ArgoCD get installed in the first place? The Break Glass steps above illustrate step by step how to bootstrap a cluster, but the general idea is you have to install a few items manually, via kubectl apply, and once those are in place, you add their manifest directories as Projects inside of ArgoCD, and it will start to monitor them from there. From then on, to modify or update any of those applications and configurations, you simply push changes to the repository, and ArgoCD will sync them to the cluster. ArgoCD will deploy applications via the same mechanism, although to make roles and permissions management easier, applications developers deploy would be stored in a separate repository from the kubernetes infrastructure applications and configuration.

1. Create and seal the argo repo secret

   • The ArgoCD kustomization requires a sealed secret that ArgoCD will use to communicate with the git repos containing the application manifests it will keep in sync with k8s. An unsealed secret needs to be created first of the form:

     apiVersion: v1
     kind: Secret
     metadata:
       name: <secret-name>
       namespace: argocd
       labels:
         argocd.argoproj.io/secret-type: repository
       annotations:
         sealedsecrets.bitnami.com/managed: "true"
     stringData:
       type: git
       url: <[email protected]:account/repository>
       username: <username>
       password: <gitlab access token>

   • Note that the URL should point to the bootstrap repository itself in this example.

   • The password should be a github personal access token with at least read repository permissions.

   • Sealed secrets require a k8s cluster to be established first, the kubeseal command below will use a secret from the k8s control plane as an encryption key or something to that effect, that's why there are no sealed secrets present initially.

   • Create the unsealed secret yaml file

   • Run kubeseal to seal the secret, put the sealed secret in the manifests/argocd folder so the kustomization can reference it.

     kubeseal --format yaml secret.yaml >manifests/argocd/sealed-secret.yaml

     or

     Get-Content .\secret.yaml | kubeseal --format yaml >.\manifests\argocd\sealed-secret.yaml

2. Install argo manually

   • Make sure the secret has been updated in the file manifests/argocd/sealed-secret.yaml

   • Apply the kustomized manifests:

     kubectl kustomize --enable-helm manifests/argocd >argocd-deployment.yaml
     # Verify yaml
     kubectl apply -f argocd-deployment.yaml

   • Verify all the ArgoCD pods have started up.

3. Take over both sealed-secrets controller and ArgoCD by installing both the ArgoCD and Tools namespace root applications.

   kubectl apply -f root-apps/argocd.yaml
   kubectl apply -f root-apps/tools.yaml

Maintain Tools

Should be able to just push changes to the manifests repo(s) in order for things to update.

Deploy to External Cluster

Use argocd cli to create a connection and configure the external cluster.

argocd login <argocd url> # use admin creds
argocd cluster add <external cluster's context name in .kube/config>

Create a Project and ApplicationSet pointing to the external cluster

Add applications.

Profit.