K8s Cluster Setup

Introduction

The following guide uses RKE2 to set up the Kubernetes (K8s) cluster.

Prerequisites

• The requirements for setting up the cluster are met as given here.

• The following tools are installed on all the nodes and the client machine.

  • ufw , wget , curl , kubectl , istioctl , helm , jq

Firewall setup

• Set up firewall rules on each node. The following uses ufw to setup firewall.

  • SSH into each node, and change to superuser.

  • Run the following command for each rule in the following table

  ufw allow from <from-ip-range-allowed> to any port <port/range> proto <tcp/udp>

  • Example

  ufw allow from any to any port 22 proto tcp
  ufw allow from 10.3.4.0/24 to any port 9345 proto tcp

  • Enable ufw.

  ufw enable
  ufw default deny incoming

  • Additional Reference: RKE2 Networking Requirements

Protocol	Port	Should be accessible by only	Description
TCP	22		SSH
TCP	80		Postgres ports
TCP	443		Postgres ports
TCP	5432		Postgres port
TCP	9345	RKE2 agent nodes	Kubernetes API
TCP	6443	RKE2 agent nodes	Kubernetes API
UDP	8472	RKE2 server and agent nodes	Required only for Flannel VXLAN
TCP	10250	RKE2 server and agent nodes	kubelet
TCP	2379	RKE2 server nodes	etcd client port
TCP	2380	RKE2 server nodes	etcd peer port
TCP	30000:32767	RKE2 server and agent nodes	NodePort port range

K8s setup

• The following setup has to be done for each cluster node.

• Choose odd number of server nodes. Example if there are 3 nodes, choose 1 server node and two agent nodes. If there are 7 nodes, choose 3 server nodes and 4 agent nodes.

• Clone the https://github.com/OpenG2P/openg2p-deployment and go to kuberenetes/rke2 directory.
• For the first server node:

  • Configure rke2-server.conf.primary.template,

  • SSH into the node. Place the file to this path: /etc/rancher/rke2/config.yaml. Create the directory if not present already. mkdir -p /etc/rancher/rke2 .

  • Run this to download rke2.

    curl -sfL https://get.rke2.io | sh -

  • Run this to start rke2 server:

    systemctl enable rke2-server
    systemctl start rke2-server

• For subsequent server and agent nodes:

  • Configure rke2-server.conf.subsequent.template or rke2-agent.conf.template, with relevant ips for each node.

  • SSH into each node place the relevant file to this path: /etc/rancher/rke2/config.yaml, based on whether its a worker node, or control-plane node. (If worker use agent file. If control-plane use server file).

  • Run this to get download rke2.

    curl -sfL https://get.rke2.io | sh -

  • To start rke2, use this

    systemctl enable rke2-server
    systemctl start rke2-server

    or, based on server or agent.

    systemctl enable rke2-agent
    systemctl start rke2-agent

• Execute these commands on a server node.

  • echo -e 'export PATH="$PATH:/var/lib/rancher/rke2/bin"\nexport KUBECONFIG="/etc/rancher/rke2/rke2.yaml"' >> ~/.bashrc
    source ~/.bashrc

  • kubectl get nodes

• Additional Reference: RKE2 High Availabilty Installation

Cluster import into Rancher.

• This section assumes a Rancher server has already been setup and operational. Rancher Server Setup in case not already done.
• Navigate to Cluster Management section in Rancher.

• Click on Import Existing cluster. And follow the steps to import the newly created cluster.

• After Rancher import, do not use the the kubeconfig from server anymore. Use it only via downloading kubeconfig from rancher.

Longhorn setup

• Use this to install longhorn. Longhorn Install as a Rancher App

Istio setup

• The following setup can be done from the client machine. This install Istio Operator, Istio Service Mesh, Istio Ingressgateway components.

• From kuberenetes/istio directory, configure the istio-operator.yaml, and run;

  istioctl operator init
  kubectl apply -f istio-operator.yaml

  • If an external Loadbalancer is being used, then use the istio-operator-external-lb.yaml file.

    kubectl apply -f istio-operator-external-lb.yaml

  • Configure the operator.yaml with any further configuration.

• Gather Wildcard TLS certificate and key and run;

  kubectl create secret tls tls-openg2p-ingress -n istio-system \
      --cert=<CERTIFICATE PATH> \
      --key=<KEY PATH>

• Create istio gateway for all hosts using this command:

  kubectl apply -f istio-gateway.yaml

  • If using external loadbalancer/external TLS termination, use the istio-gateway-no-tls.yaml file.

    kubectl apply -f istio-gateway-no-tls.yaml

Adding new nodes

• From kuberenetes/rke2 directory, take either the rke2-server.conf.subsequent.template or rke2-agent.conf.template based on whether the new node is control plane node or Worker node. Copy this file to /etc/rancher/rke2/config.yaml in the new node.
• Configure the the config.yaml with relevant values.

• Run this to download rke2.

  curl -sfL https://get.rke2.io | sh -

• Run this to start rke2 node:

  systemctl enable rke2-server
  systemctl start rke2-server