High Availability with DNS

The purpose of this document is to describe steps to deploy an RKE2 Kubernetes distribution in high availability with DNS.

Prerequisites

Preparing for Deployment

All control-plane nodes must be ready as per the environment preparation mentioned in RKE2 Control plane Deployment | Environment-Preparation.

Installation and Configuration Steps

1. Setup DNS Configurations

For DNS based load balancing you need to setup a virtual FQDN that can point to all control plane nodes. Contact your network administrator to do that.

• The DNS server should perform health checks on the Control-Plane nodes availability on ports 6443, 9345, 80 and 443. Otherwise routing to control-plane nodes will have to be managed manually.

Step 2. Create first Control Plane node

Follow RKE2 Control plane Deployment to create the first control-plane node.

Get the server node token from the first control plane. This is required for adding remaining control plane and worker nodes.

cat /var/lib/rancher/rke2/server/node-token

Step 3. Adding Remaining Control Plane Nodes

Before proceeding, make sure your control plane environment is ready following RKE2 Control plane Deployment | Environment-Preparation

1. Create the directories as listed below in the control plane nodes to be added.

   BASH

   mkdir -p /etc/rancher/rke2/
   mkdir -p  /var/lib/rancher/rke2/server/manifests/

2. Create a deployment manifest called config.yaml and replace <FQDN> with the FQDN/IP of the first conrtol plane.

   BASH

   cat<<EOF|tee /etc/rancher/rke2/config.yaml
   server: https://<FQDN>:9345
   token: [token from /var/lib/rancher/rke2/server/node-token on server node 1]
   write-kubeconfig-mode: "0644" 
   tls-san:
     - <FQDN>
   etcd-expose-metrics: true
   # Make a etcd snapshot every 6 hours
   etcd-snapshot-schedule-cron: "0 */6 * * *"
   # Keep 56 etcd snapshorts (equals to 2 weeks with 6 a day)
   etcd-snapshot-retention: 56
   cni:
     - canal
   
   EOF

3. Ingress-Nginx config for RKE2 - By default RKE-2 based ingress controller does not allow additional snippet information in ingress manifests, create this config before starting the deployment of RKE2.

   BASH

   cat<<EOF| tee /var/lib/rancher/rke2/server/manifests/rke2-ingress-nginx-config.yaml
   ---
   apiVersion: helm.cattle.io/v1
   kind: HelmChartConfig
   metadata:
     name: rke2-ingress-nginx
     namespace: kube-system
   spec:
     valuesContent: |-
       controller:
         metrics:
           service:
             annotations:
               prometheus.io/scrape: "true"
               prometheus.io/port: "10254"
         config:
           use-forwarded-headers: "true"
         allowSnippetAnnotations: "true"
   EOF

Step 4. Install RKE2 HA with DNS

1. Begin the RKE2  Deployment. Starting the Service will take approx. 10-15 minutes based on the network connection

   BASH

   curl -sfL https://get.rke2.io |INSTALL_RKE2_TYPE=server  sh - 

2. Start the RKE2 service

   BASH

   systemctl start rke2-server

3. Enable the RKE2 Service

   BASH

   systemctl enable rke2-server

4. By default, RKE2 deploys all the binaries in /var/lib/rancher/rke2/bin  path,  add this path to system's default PATH for kubectl utility to work appropriately

   BASH

   export PATH=$PATH:/var/lib/rancher/rke2/bin
   export KUBECONFIG=/etc/rancher/rke2/rke2.yaml

5. Append these lines into current user's .bashrc  file.

   BASH

   echo "export PATH=$PATH:/var/lib/rancher/rke2/bin" >> $HOME/.bashrc
   echo "export KUBECONFIG=/etc/rancher/rke2/rke2.yaml"  >> $HOME/.bashrc 

Step 5. Deploy Worker Nodes

Follow the Deployment Prerequisites from RKE2 Control plane Deployment for each worker node before deployment i.e disable firewall on all worker nodes.

On each worker node,

1. Run the following command to install RKE2 agent on the worker.

   CODE

   curl -sfL https://get.rke2.io | INSTALL_RKE2_TYPE="agent" sh -

2. Enable the rke2-agent service by using the following command.

   CODE

   systemctl enable rke2-agent.service

3. Create a directory by running the following commands.

   CODE

   mkdir -p /etc/rancher/rke2/

4. Add/edit /etc/rancher/rke2/config.yaml and update the following fields.

   1. <Control-Plane-IP> This is the IP for the first control-plane node.

   2. <Control-Plane-TOKEN> This is the token from Step 2.

      CODE

      server: https://<Control-Plane-IP>:9345
      token: <Control-Plane-TOKEN>

5. Start the service by using follow command.

   CODE

   systemctl start rke2-agent.service

Next Steps

1. Choose storage - See Storage Solution - Getting Started

2. CX-Core deployment on Kubernetes

.