K3s install reference

This guide provides a reference on how we installed k3s on the single VM that is running in Contabo. K3s is perfect to use in for a single node Kubernetes cluster since it is very easy to install and consumes minimal resources.

However, in this environment we'll use k3s in a rather complicated setup (mainly for fun):

• we didn't install the built-in traefik ingress, we use nginx instead (that is the straightforward part)
• we don't use the build-in flannel CNI networking, we installed cilium instead, moreover we'll use the kube-proxy replacement feature for accelerated networking (more on the here)

Install K3s with Cilium

We'll install k3s without:

• traefik (we'll install nginx)
• flannel (cilium will be the CNI plugin)
• kube-proxy (cilium will do this feature)
• network policy (cilium will do this as well)

curl -sfL https://get.k3s.io | INSTALL_K3S_EXEC='--disable traefik --flannel-backend=none --disable-kube-proxy --disable-network-policy' sh -

It should take k3s about 30s to install. After it add the following housekeeping commands (just bash completion, and have the kube config file in the right place):

mkdir -p $HOME/.kube
sudo cp -i /etc/rancher/k3s/k3s.yaml $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

echo 'source <(kubectl completion bash)' >>~/.bashrc
echo 'alias k=kubectl' >>~/.bashrc
echo 'complete -o default -F __start_kubectl k' >>~/.bashrc

kubectl version
kubectl get nodes && kubectl get pods -A

Notice, that the node is currently in NotReady status, since there is no CNI installed yet.

Download helm and add the cilium repo:

curl https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3 | bash
echo 'source <(helm completion bash)' >>~/.bashrc
helm repo add cilium https://helm.cilium.io/
helm repo update

Install cilium with the kube-proxy replacement feature:

export IP=$(ip -f inet addr show eth0 | grep -Po 'inet \K[\d.]+')
echo $IP
helm install cilium cilium/cilium --version 1.14.1  --namespace kube-system --set tunnel=disabled --set autoDirectNodeRoutes=true --set kubeProxyReplacement=strict --set loadBalancer.mode=dsr --set k8sServiceHost=$IP --set k8sServicePort=6443 --set operator.replicas=1 --set ipv4NativeRoutingCIDR=10.0.0.0/8

Check the cilium pods in the kube-system namespace:

kubectl get pods -n kube-system

As soon as they are in Running status, the all pods and the node should become in Running status very soon.

There you go, you have a single node but fully fledged Kubernetes cluster with accelerated networking.

Install ArgoCD

This is basically the same guide as in the main readme, the only differences are i) the DNS name of the cluster, and ii) the folder we'll point ArgoCD in our git repo.

For reference, we use the following values.yaml file (fill it with your own domain):

server:
  ingress:
    enabled: true
    ingressClassName: nginx
    https: true
    annotations: 
      cert-manager.io/cluster-issuer: letsencrypt-prod
      nginx.ingress.kubernetes.io/ssl-redirect: "true"
      nginx.ingress.kubernetes.io/backend-protocol: HTTPS
    hosts: 
      - argocd.contabo-eu.stunner.cc
    tls: 
    - hosts:
      - argocd.contabo-eu.stunner.cc
      secretName: argocd-tls

Install ArgoCD with this override file:

helm repo add argo https://argoproj.github.io/argo-helm
helm repo update
helm install -n argocd --create-namespace  -f values.yaml argocd argo/argo-cd

Step 3: add the ArgoCD Application that will install everything else. The following is the content of the argocd-applications.yaml file:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: argocd-applications
  namespace: argocd
spec:
  destination:
    namespace: argocd
    server: https://kubernetes.default.svc
  project: default
  source:
    directory:
      jsonnet: {}
      recurse: true
    path: ./contabo-eu/argocd-applications
    repoURL: https://github.com/l7mp/demo-clusters.git
    targetRevision: HEAD
  syncPolicy:
    automated:
      prune: true
      selfHeal: true
    syncOptions:
    - CreateNamespace=true

Apply this manifest and wait for ArgoCD to sync everything:

kubectl apply -f argocd-applications.yaml