Overview
Kubernetes is the next Evolution of Docker swarm, so in order to configure it, we have to firstly configure the Docker (just without the swarm this time) We will configure 3 servers again:
- One master
- Two Workers
Since I hate seeing only Debian based, I will do it in both: Ubuntu and Centos. Firstly we will be the Ubuntu. So let's get going:
Provision the VMs
You can return use the first section of the Vagrant advanced configurations or you can continue here, where we will do pretty much the same. I like wasting space :D
So let's get going with Vagrant again :)
Kubernetes 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 = 1024 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 = "kubernetes-setup/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 = "kubernetes-setup/node-playbook.yml" ansible.extra_vars = { node_ip: "192.168.50.#{i + 10}", } end end end end
As you can see, we are refering to two files here:
- master-playbook.yml - Ansible Playbook for the Master node
- node-playbook.yml - Ansible Playbook for the other Nodes.
Please create the following files as follows:
Configure the Master Playbook
Let's start building the master playbook:
Master Playbook File
--- - 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
Remove the swap
Please bare in mind that the kubelet won't install if the swap is enabled, so we have to add the following:
Remove the swap
- name: Disable swap command: swapoff -a when: ansible_swaptotal_mb > 0
Install Kubelet, kubeadm, kubectl
After that, we can add a task to install the: kubelet, kubeadm and kubectl using the below code.
Add Kubelet, kubeadm and kubectl
- 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 }} - name: Restart kubelet service: name: kubelet daemon_reload: yes state: restarted
Initialize the Kubernetes
Finally, we can add the Tasks for the Initialization as follows:
Initialize Kubernetes
- 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
Configure Vagrant User for the Cluster
Since we are using vagrant, we can setup vagrant to access the Kubernetes Cluster using the following Task:
Configure Vagrant user
- 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
Configure the Network provider and policy engine
Configure network provider and policy Engine
- 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
Configure the Node Playbook
To configure the other nodes, create a node-playbook.yml with all the data above, except the initialization of the Kerberos. We will setup a join file which will be used in the playbook for the other nodes:
Generate Join Command
- 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"
The generated, from Kubernetes, join command will be saved in file called: “join-command” which will be executed by the playbook:
Configure handlers
We have to also setup the handlers for checking the Docker daemon:
Configure handlers
handlers: - name: docker status service: name=docker state=started
Finally we can configure the node-playbook.yml
Node-playbook.yml config
- 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