Author: Naresh L J (Infosys)
Objective
This blog post describes the steps required to setup a multi node Kubernetes cluster for development purposes. This setup provides a production-like cluster that can be setup on your local machine.
Why do we require multi node cluster setup?
Multi node Kubernetes clusters offer a production-like environment which has various advantages. Even though Minikube provides an excellent platform for getting started, it doesn’t provide the opportunity to work with multi node clusters which can help solve problems or bugs that are related to application design and architecture. For instance, Ops can reproduce an issue in a multi node cluster environment, Testers can deploy multiple versions of an application for executing test cases and verifying changes. These benefits enable teams to resolve issues faster which make the more agile.
Why use Vagrant and Ansible?
Vagrant is a tool that will allow us to create a virtual environment easily and it eliminates pitfalls that cause the works-on-my-machine phenomenon. It can be used with multiple providers such as Oracle VirtualBox, VMware, Docker, and so on. It allows us to create a disposable environment by making use of configuration files.
Ansible is an infrastructure automation engine that automates software configuration management. It is agentless and allows us to use SSH keys for connecting to remote machines. Ansible playbooks are written in yaml and offer inventory management in simple text files.
Prerequisites
- Vagrant should be installed on your machine. Installation binaries can be found here.
- Oracle VirtualBox can be used as a Vagrant provider or make use of similar providers as described in Vagrant’s official documentation.
- Ansible should be installed in your machine. Refer to the Ansible installation guide for platform specific installation.
Setup overview
We will be setting up a Kubernetes cluster that will consist of one master and two worker nodes. All the nodes will run Ubuntu Xenial 64-bit OS and Ansible playbooks will be used for provisioning.
Step 1: Creating a Vagrantfile
Use the text editor of your choice and create a file with named Vagrantfile, inserting the code below. The value of N denotes the number of nodes present in the cluster, it can be modified accordingly. In the below example, we are setting the value of N as 2.
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"
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"
end
end
end
Step 2: Create an Ansible playbook for Kubernetes master.
Create a directory named kubernetes-setup in the same directory as the Vagrantfile. Create two files named master-playbook.yml and node-playbook.yml in the directory kubernetes-setup.
In the file master-playbook.yml, add the code below.
Step 2.1: Install Docker and its dependent components.
We will be installing the following packages, and then adding a user named “vagrant” to the “docker” group.
- docker-ce
- docker-ce-cli
- containerd.io