Kubernetes Workshop

Installing 3 machine Kubernetes cluster on bare metal with the help of Ansible

Based on Digital Ocean Tutorial

What you need?

• Ansible installed on your local machine
• SSH access to 3 machines (check that connecting works with root user)
• Ubuntu 20.04 installed
• At least 2 vCPUs and 2GB RAM for each machine

Creating Kubernetes cluster with Ansible

• Make a copy of the hosts.example file and rename it to `hosts
• Edit the hosts file and add the IP addresses of the machines
• Also add path to your SSH public key, which you are using for connecting to the machines

Initial setup

We will create ubuntu user and add sudo privileges on all machines. Also the public keys will be added, so you can SSH with same keys

Run Ansible playbook:

ansible-playbook -i hosts 01-initial.yaml

Now we are able to SSH with the ubuntu user

Installing Kubernetes dependencies

Now we install tools needed by Kubernetes like Docker, kubelet and kubeadm

Run Ansible playbook:

ansible-playbook -i hosts 02-kube-dependencies.yaml

Setting up the control-plane node

We will initialize the cluster with kubeadm and install networking and some configurations. Also the kubectl tool will be installed to control-plane node.

Run Ansible playbook:

ansible-playbook -i hosts 03-control-plane.yaml

Setting up the worker nodes

Now we first get the kubeadm join command from control plane, and then we will join the worker nodes to the cluster

Run Ansible playbook:

ansible-playbook -i hosts 04-workers.yaml

Setup local kubectl

At the control-plane setup stage we copied the KUBECONFIG file, so we can use kubectl from local machine to control cluster.

Run: export KUBECONFIG=$(pwd)KUBECONFIG

Now check that you are connected to correct cluster: kubectl cluster-info and/or kubectl get nodes

Deploying example application

In example-app folder you can find two files: deployment.yaml and service.yaml

• deployment.yaml will deploy very basic nginx container
• service.yaml will create NodePort service, so you can connect to application with worker node ip and specific port

Deploy nginx by running:

kubectl apply -f example-app/deployment.yaml

Check that it's deployed:

kubectl get deployments

Deploy Service by running:

kubectl apply -f example-app/service.yaml

Check that service is created and also port is assigned:

kubectl get services

Now you can open up the application in browser with http://<worker-node-ip>:<port>

Assigned port range is usually 30000-32767