K8S cluster

Kubernetes-Cluster

Code below is used to deploy a full-fledged kubernetes cluster with N nodes.
Tested in March of 2021.

master-playbook.yml

---
- hosts: all
  become: true
  tasks:
  - name: Install packages that allow apt to be used over HTTPS
    apt:
      name: "{{ packages }}"
      state: present
      update_cache: yes
    vars:
      packages:
      - apt-transport-https
      - ca-certificates
      - curl
      - gnupg-agent
      - software-properties-common

  - name: Add an apt signing key for Docker
    apt_key:
      url: https://download.docker.com/linux/ubuntu/gpg
      state: present

  - name: Add apt repository for stable version
    apt_repository:
      repo: deb [arch=amd64] https://download.docker.com/linux/ubuntu xenial stable
      state: present

  - name: Install docker and its dependecies
    apt:
      name: "{{ packages }}"
      state: present
      update_cache: yes
    vars:
      packages:
      - docker-ce
      - docker-ce-cli
      - containerd.io
    notify:
      - docker status

  - name: Add vagrant user to docker group
    user:
      name: vagrant
      group: docker

  - name: Remove swapfile from /etc/fstab
    mount:
      name: "{{ item }}"
      fstype: swap
      state: absent
    with_items:
      - swap
      - none

  - name: Disable swap
    command: swapoff -a
    when: ansible_swaptotal_mb > 0

  - name: Add an apt signing key for Kubernetes
    apt_key:
      url: https://packages.cloud.google.com/apt/doc/apt-key.gpg
      state: present


  - name: Adding apt repository for Kubernetes
    apt_repository:
      repo: deb https://apt.kubernetes.io/ kubernetes-xenial main
      state: present
      filename: kubernetes.list

  - name: Install Kubernetes binaries
    apt:
      name: "{{ packages }}"
      state: present
      update_cache: yes
    vars:
      packages:
        - kubelet
        - kubeadm
        - kubectl

  - name: Configure node ip
    lineinfile:
      path: /etc/default/kubelet
      line: KUBELET_EXTRA_ARGS=--node-ip={{ node_ip }}
      create: yes

  - name: Restart kubelet
    service:
      name: kubelet
      daemon_reload: yes
      state: restarted

  - name: detect docker's cgroup-driver
    shell: docker info 2>/dev/null |grep -i cgroup | cut -d":" -f2 | tr -d " "
    register: docker_cgroup_driver

  - name: Replace docker cdriver
    replace:
      dest: /etc/systemd/system/kubelet.service.d/10-kubeadm.conf
      regexp: '--cgroup-driver=(systemd|cgroupfs)'
      replace: '--cgroup-driver={{docker_cgroup_driver.stdout}}'
      backup: no
  
  - name: Initialize the Kubernetes cluster using kubeadm
    command: kubeadm init --apiserver-advertise-address="192.168.50.10" --apiserver-cert-extra-sans="192.168.50.10"  --node-name k8s-master --pod-network-cidr=192.168.0.0/16


  - name: Setup kubeconfig for vagrant user
    command: "{{ item }}"
    with_items:
     - mkdir -p /home/vagrant/.kube
     - cp -i /etc/kubernetes/admin.conf /home/vagrant/.kube/config
     - chown vagrant:vagrant /home/vagrant/.kube/config


  - name: Install calico pod network
    become: false
    command: kubectl create -f https://docs.projectcalico.org/manifests/calico.yaml


  - name: Generate join command
    command: kubeadm token create --print-join-command
    register: join_command

  - name: Copy join command to local file
    local_action: copy content="{{ join_command.stdout_lines[0] }}" dest="./join-command"
    become: false


  handlers:
    - name: docker status
      service: name=docker state=started

node-playbook.yml

---
- hosts: all
  become: true
  tasks:
  - name: Install packages that allow apt to be used over HTTPS
    apt:
      name: "{{ packages }}"
      state: present
      update_cache: yes
    vars:
      packages:
      - apt-transport-https
      - ca-certificates
      - curl
      - gnupg-agent
      - software-properties-common

  - name: Add an apt signing key for Docker
    apt_key:
      url: https://download.docker.com/linux/ubuntu/gpg
      state: present

  - name: Add apt repository for stable version
    apt_repository:
      repo: deb [arch=amd64] https://download.docker.com/linux/ubuntu xenial stable
      state: present

  - name: Install docker and its dependecies
    apt:
      name: "{{ packages }}"
      state: present
      update_cache: yes
    vars:
      packages:
      - docker-ce
      - docker-ce-cli
      - containerd.io
    notify:
      - docker status

  - name: Add vagrant user to docker group
    user:
      name: vagrant
      group: docker

  - name: Remove swapfile from /etc/fstab
    mount:
      name: "{{ item }}"
      fstype: swap
      state: absent
    with_items:
      - swap
      - none

  - name: Disable swap
    command: swapoff -a
    when: ansible_swaptotal_mb > 0

  - name: Add an apt signing key for Kubernetes
    apt_key:
      url: https://packages.cloud.google.com/apt/doc/apt-key.gpg
      state: present

  - name: Adding apt repository for Kubernetes
    apt_repository:
      repo: deb https://apt.kubernetes.io/ kubernetes-xenial main
      state: present
      filename: kubernetes.list

  - name: Install Kubernetes binaries
    apt:
      name: "{{ packages }}"
      state: present
      update_cache: yes
    vars:
      packages:
        - kubelet
        - kubeadm
        - kubectl

  - name: Configure node ip
    lineinfile:
      path: /etc/default/kubelet
      line: KUBELET_EXTRA_ARGS=--node-ip={{ node_ip }}
      create: yes

  - name: Restart kubelet
    service:
      name: kubelet
      daemon_reload: yes
      state: restarted

  - name: Copy the join command to server location
    copy: src=join-command dest=/tmp/join-command.sh mode=0777

  - name: Join the node to cluster
    command: sh /tmp/join-command.sh

  handlers:
    - name: docker status
      service: name=docker state=started

Vagrantfile

IMAGE_NAME = "bento/ubuntu-16.04"
N = 2

Vagrant.configure("2") do |config|
    config.ssh.insert_key = false

    config.vm.provider "virtualbox" do |v|
        v.memory = 2048
        v.cpus = 2
    end
      
    config.vm.define "k8s-master" do |master|
        master.vm.box = IMAGE_NAME
        master.vm.network "private_network", ip: "192.168.50.10"
        master.vm.hostname = "k8s-master"
        master.vm.provision "ansible" do |ansible|
            ansible.playbook = "master-playbook.yml"
            ansible.extra_vars = {
                node_ip: "192.168.50.10",
            }
        end
    end

    (1..N).each do |i|
        config.vm.define "node-#{i}" do |node|
            node.vm.box = IMAGE_NAME
            node.vm.network "private_network", ip: "192.168.50.#{i + 10}"
            node.vm.hostname = "node-#{i}"
            node.vm.provision "ansible" do |ansible|
                ansible.playbook = "node-playbook.yml"
                ansible.extra_vars = {
                    node_ip: "192.168.50.#{i + 10}",
                }
            end
        end
    end
end