Includes configuring pre-requisites to install kubeadm

step 01) Enable following ports and protcols 
  on kubemaster : Open following ports : https://kubernetes.io/docs/reference/networking/ports-and-protocols/

sudo ufw status
sudo ufw enable
sudo ufw allow 80/tcp
sudo ufw allow 443/tcp
sudo ufw allow 22/tcp
sudo ufw allow 6443/tcp
sudo ufw allow 2379/tcp
sudo ufw allow 2380/tcp
sudo ufw allow 10250/tcp
sudo ufw allow 10259/tcp
sudo ufw allow 10257/tcp
sudo ufw allow 30000:32767/tcp
sudo ufw reload
sudo ufw status

######  ----- kubenode01, kubenode02 ---#

sudo ufw status
sudo ufw enable
sudo ufw allow 80/tcp
sudo ufw allow 443/tcp
sudo ufw allow 22/tcp
sudo ufw allow 10250/tcp
sudo ufw allow 30000:32767/tcp
sudo ufw reload
sudo ufw status

sudo iptables -L    #--- on all nodes
step 02) 
  ------ Install Container Runtime ----------#

#---- on all nodes : Forwarding IPv4 and letting iptables see bridged traffic : https://kubernetes.io/docs/setup/production-environment/container-runtimes/#forwarding-ipv4-and-letting-iptables-see-bridged-traffic

cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
overlay
br_netfilter
EOF

sudo modprobe overlay
sudo modprobe br_netfilter
sysctl params required by setup, params persist across reboots 
  cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-iptables  = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward                 = 1
EOF
Apply sysctl params without reboot 
  sudo sysctl --system
Verify that the br_netfilter, overlay modules are loaded 
  lsmod | grep br_netfilter
lsmod | grep overlay
Verify that the net.bridge.bridge-nf-call-iptables, net.bridge.bridge-nf-call-ip6tables, and net.ipv4.ip_forward system variables are set to 1 in sysctl config 
  sysctl net.bridge.bridge-nf-call-iptables net.bridge.bridge-nf-call-ip6tables net.ipv4.ip_forward
We are selecting option 2 here using apt-get

install via package manager : https://docs.docker.com/engine/install/ubuntu/ Remove old versions

  for pkg in docker.io docker-doc docker-compose docker-compose-v2 podman-docker containerd runc; do sudo apt-get remove $pkg; done
setup docker repository
Add Docker’s official GPG key: 
  sudo apt-get update
sudo apt-get install ca-certificates curl
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc
Add the repository to Apt sources: 
  echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update
Install package
we are only interested in containerd 
  #---- on all nodes : Install container runtime ----------- https://github.com/containerd/containerd/blob/main/docs/getting-started.md

sudo apt-get install containerd.io 
systemctl status containerd
check and install cgroup driver for container runtime and kubelet to integrate with control groups for getting resources from the instance.

#! both kubelet and containerd should use same cgroup driver

find if the instances are systemd instances 
  systemctl # if this command runs its a systemd system
ps -p 1 #output should be something   1 ?        Ss     0:02 /sbin/init systemd
Configure cgroup driver 
  https://kubernetes.io/docs/setup/production-environment/container-runtimes/#containerd

sudo vi /etc/containerd/config.toml
copy following content to install cgroup drivers : Tip : delete all the content inside that file using command mode :%d and copy following content. 
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
    SystemdCgroup = true
save above config and run following 
  sudo systemctl restart containerd
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Last updated 03 Jun 2024, 13:43 +0530 . history