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rke.md

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Install kubectl and RKE:

  • Install dependencies
sudo apt install wget

First of all, on the rke-elk-master Master node,

  • Install Kubectl:
curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl

chmod +x ./kubectl

sudo mv ./kubectl /usr/local/bin/kubectl

kubectl version --client
  • Install RKE:
curl -s https://api.github.com/repos/rancher/rke/releases/latest | grep download_url | grep amd64 | cut -d '"' -f 4 | wget -qi -

chmod +x rke_linux-amd64

sudo mv rke_linux-amd64 /usr/local/bin/rke

rke -v
  • Install Helm:
curl -fsSL -o get_helm.sh https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3

chmod 700 get_helm.sh

./get_helm.sh

helm version
  • Include the binaries in the system path:
sudo ln -s /usr/local/bin/kubectl /usr/bin/kubectl
sudo ln -s /usr/local/bin/helm /usr/bin/helm
sudo ln -s /usr/local/bin/rke /usr/bin/rke

RKE Cluster Pre-flight Setup

Before initializing the RKE cluster, perform the following on all three nodes, using the root user:

sudo yum update -y
  • Synchronize Chronyd: systemctl status chronyd
  • Load kernel modules for RKE
for module in br_netfilter ip6_udp_tunnel ip_set ip_set_hash_ip ip_set_hash_net iptable_filter iptable_nat iptable_mangle iptable_raw nf_conntrack_netlink nf_conntrack nf_conntrack_ipv4   nf_defrag_ipv4 nf_nat nf_nat_ipv4 nf_nat_masquerade_ipv4 nfnetlink udp_tunnel veth vxlan x_tables xt_addrtype xt_conntrack xt_comment xt_mark xt_multiport xt_nat xt_recent xt_set  xt_statistic xt_tcpudp;
     do
       if ! lsmod | grep -q $module; then
         echo "module $module is not present";
         modprobe $module
       fi;
    done
  • Disable swap by commenting out the swap option in /etc/fstab and turn off swap sudo swapoff -a

Confirm swap is disabled (size should be 0).

free -h

# Output
              total        used        free      shared  buff/cache   available
Mem:           3928         406        1088          24        2433        3206
Swap:             0           0           0
  • Customize sysctl parameters:
sudo tee -a /etc/sysctl.d/99-kubernetes.conf <<EOF
net.bridge.bridge-nf-call-iptables  = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

sysctl --system
  • Install Docker:
curl https://releases.rancher.com/install-docker/20.10.sh | sh
  • Enable and start the docker service
systemctl enable docker
systemctl start docker
systemctl status docker
  • Add the rke user
sudo adduser rke

The root user can't run RKE because there is a known bug of OpenSSH on Red Hat's Bugzilla about socket forwarding. Therefore, a user to run RKE containers will be created. We also added the user to the Docker group:

sudo usermod -aG docker rke
  • Enable SSH Access

SSH access using SSH keys must be allowed, in order to allow RKE to SSH from the RKE (rke-elk-master in this case) machine, into all of the VMs. In this regard, on the Master machine, create an SSH key-pair:

ssh-keygen -o -a 100 -t rsa -b 4096 -N "" -f ~/.ssh/id_rsa -C "rke key"

Once created, copy the public key to the authorized-keys file into all of the remaining VMs. On every machine, perform the following commands, to create the required files and folders:

sudo su rke
mkdir -p ~/.ssh
touch ~/.ssh/authorized_keys 
chmod -R go= ~/.ssh

From the Master machine, copy the ~/.ssh/id_rsa.pub key to the ~.ssh/authorized_keys file of every remaining machine. Make sure you are using the rke user.

  • Disable firewalld Using the original admin account (or root), stop the firewalld service:
sudo systemctl disable firewalld
sudo systemctl stop firewalld
sudo systemctl status firewalld

RKE Cluster Setup

Using the admin user, initiate the RKE cluster setup wizard from the RKE machine rke config --name cluster.yml:

rke config --name cluster.yml
[+] Cluster Level SSH Private Key Path [~/.ssh/id_rsa]: 
[+] Number of Hosts [1]: 3
[+] SSH Address of host (1) [none]: 10.0.3.4
[+] SSH Port of host (1) [22]: 
[+] SSH Private Key Path of host (10.0.3.4) [none]: 
[-] You have entered empty SSH key path, trying fetch from SSH key parameter
[+] SSH Private Key of host (10.0.3.43) [none]: 
[-] You have entered empty SSH key, defaulting to cluster level SSH key: ~/.ssh/id_rsa
[+] SSH User of host (10.0.3.4) [ubuntu]: rke
[+] Is host (10.0.3.4) a Control Plane host (y/n)? [y]: 
[+] Is host (10.0.3.4) a Worker host (y/n)? [n]: 
[+] Is host (10.0.3.4) an etcd host (y/n)? [n]: y
[+] Override Hostname of host (10.0.3.4) [none]: 
[+] Internal IP of host (10.0.3.4) [none]: 10.0.3.4
[+] Docker socket path on host (10.0.3.4) [/var/run/docker.sock]: 
[+] SSH Address of host (2) [none]: 10.0.3.5
[+] SSH Port of host (2) [22]: 
[+] SSH Private Key Path of host (10.0.3.5) [none]: 
[-] You have entered empty SSH key path, trying fetch from SSH key parameter
[+] SSH Private Key of host (10.0.3.5) [none]: 
[-] You have entered empty SSH key, defaulting to cluster level SSH key: ~/.ssh/id_rsa
[+] SSH User of host (10.0.3.5) [ubuntu]: rke
[+] Is host (10.0.3.5) a Control Plane host (y/n)? [y]: n
[+] Is host (10.0.3.5) a Worker host (y/n)? [n]: y
[+] Is host (10.0.3.5) an etcd host (y/n)? [n]: n
[+] Override Hostname of host (10.0.3.5) [none]: 
[+] Internal IP of host (10.0.3.5) [none]: 10.0.3.5
[+] Docker socket path on host (10.0.3.5) [/var/run/docker.sock]: 
[+] SSH Address of host (3) [none]: 10.0.3.6
[+] SSH Port of host (3) [22]: 
[+] SSH Private Key Path of host (10.0.3.6) [none]: 
[-] You have entered empty SSH key path, trying fetch from SSH key parameter
[+] SSH Private Key of host (10.0.3.6) [none]: 
[-] You have entered empty SSH key, defaulting to cluster level SSH key: ~/.ssh/id_rsa
[+] SSH User of host (10.0.3.6) [ubuntu]: rke
[+] Is host (10.0.3.6) a Control Plane host (y/n)? [y]: n
[+] Is host (10.0.3.6) a Worker host (y/n)? [n]: y
[+] Is host (10.0.3.6) an etcd host (y/n)? [n]: n
[+] Override Hostname of host (10.0.3.6) [none]: 
[+] Internal IP of host (10.0.3.6) [none]: 10.0.3.6
[+] Docker socket path on host (20.74.252.138) [/var/run/docker.sock]: 
[+] Network Plugin Type (flannel, calico, weave, canal, aci) [canal]: 
[+] Authentication Strategy [x509]: 
[+] Authorization Mode (rbac, none) [rbac]: 
[+] Kubernetes Docker image [rancher/hyperkube:v1.21.8-rancher2]: 
[+] Cluster domain [cluster.local]: 
[+] Service Cluster IP Range [10.43.0.0/16]: 
[+] Enable PodSecurityPolicy [n]: 
[+] Cluster Network CIDR [10.42.0.0/16]: 
[+] Cluster DNS Service IP [10.43.0.10]:
  • Spin the RKE cluster Use the below command to spin the cluster with the above configuration. You should be in the same location as the previously created cluster.yml file: rke up

Kubectl

Now that RKE is setup, it will create a file in the current directory named kube_config_cluster.yml. We need to move this file to a certain directory for kubectl to read from it, or point it to it.

  • method 1: move the file 
    mkdir ~/.kube
mv ./kube_config_cluster.yml ~/.kube/config
  • method 2: create an env file 
    export KUBECONFIG=$(pwd)/kube_config_cluster.yml

Note that the second method will only work during the current session, the export command should be added in the .bash_profile file so it would be consistent.

Storage

The ElasticSearch component will require storage for data persistence. Which raises the need for a dynamic method for data provisioning on a local environment (our-case) which is not required in a cloud setup.

To workaround this issue we will be using the local-path dynamic provisioner from rancher. More information here.

Follow the below steps to install and configure the local-path provisioner:

  • On the Master node, Install the local provisioned:
wget https://raw.githubusercontent.com/rancher/local-path-provisioner/master/deploy/local-path-storage.yaml
  • Configure it to the standard Storage class and change its name to standard:
vim local-path-storage.yml
  • Change the StorageClass section to resemble the following:
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
  annotations:
          storageclass.kubernetes.io/is-default-class: "true"
provisioner: rancher.io/local-path
volumeBindingMode: WaitForFirstConsumer
reclaimPolicy: Retain
  • Apply the manifest
kubectl apply -f local-path-storage.yaml
  • Check if the changes took effect with the below command you should see the name change and a (default) next to the name
kubectl get storageclass

Expected output:

NAME                 PROVISIONER             RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
standard (default)   rancher.io/local-path   Retain          WaitForFirstConsumer   false                  3m19s