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Dawid Rycerz

K3S is a lightweight and certified Kubernetes distribution, perfect for run development environments, CI/CD and IoT. It works very well with the ARM architecture. It’s packaged to a single binary that makes deployment and setup easy.

The default installation comes with:

  • embedded SQLite
  • containerd
  • flannel
  • coredns
  • traefik (ingress controller)
  • local path provisioner
  • service load balancer

All those features are more than enough for most use-cases. Of course, installation is fully configurable, so if you want etcd, docker, Nginx ingress and so on - go to official documentation page https://rancher.com/docs/k3s/latest/en/ .

Default installation

Login to machine and run:

Terminal window
curl -sfL https://get.k3s.io | sh -

and that’s it… After a few seconds, you should see that the master node is ready with k3s kubectl get node.

You will find config.yaml for kubernetes in /etc/rancher/k3s/k3s.yaml

Advanced installation with nginx-ingress, metallb and cert-manager

  1. Deploy k3s without traefik and servicelb

    Terminal window
    curl -sfL https://get.k3s.io | K3S_KUBECONFIG_MODE="644" INSTALL_K3S_EXEC=" --no-deploy=servicelb --no-deploy=traefik" sh -s -

  2. Get config from /etc/rancher/k3s/k3s.yaml and put into ~/.kube/config on your machine

  3. Install helm

    Terminal window
    curl https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3 | bash

  4. Add helm repo and update

    Terminal window
    helm repo add stable https://kubernetes-charts.storage.googleapis.com/
    helm repo update

  5. Install metallb. Range of available ip addresses for loadbalancer are set in configInline.address-pools[0].addresses[0].

    Terminal window
    helm install --namespace=kube-system \
      --set configInline.address-pools[0].name=default \
      --set configInline.address-pools[0].protocol=layer2 \
      --set configInline.address-pools[0].addresses[0]=192.168.1.10-192.168.1.50 \
      metallb stable/metallb

  6. Install nginx-ingress

    Terminal window
    helm install --namespace=kube-system \
        --set rbac.create=true \
        nginx-ingress stable/nginx-ingress

  7. Install and configure certmanager for lets-encrypt

    Terminal window
    kubectl apply -f https://raw.githubusercontent.com/jetstack/cert-manager/release-0.14/deploy/manifests/00-crds.yaml
    

    helm install --namespace=kube-system cert-manager stable/cert-manager
    

    cat <<EOF | kubectl apply -f -
    apiVersion: cert-manager.io/v1alpha2
    kind: ClusterIssuer
    metadata:
      name: letsencrypt
    spec:
      acme:
        server: https://acme-v02.api.letsencrypt.org/directory
        email: ACME_EMAIL
        privateKeySecretRef:
          name: letsencrypt
        solvers:
          - dns01:
              cloudflare:
                email: CLOUDFLARE_EMAIL
                apiKeySecretRef:
                  name: cloudflare-apikey-secret
                  key: CLOUDFLARE_APIKEY
            selector:
              dnsNames:
                - 'DOMAIN_NAME'
    EOF

    Where:

    • ACME_EMAIL - some email in yor domain (will be used to limit number of requests to acme)
    • CLOUDFLARE_EMAIL - email of your cloudflare account
    • CLOUDFLARE_APIKEY - api key to your cloudflare account
    • DOMAIN_NAME - domain that will be used in lets-encrypt certs (eg.: *.rycerz.co)

Important disclaimer

Don’t deploy everything in kube-system if it’s not test/development cluster. Be safe.