Creating a multi-node Kubernetes cluster on local machine

This guide will bring you close to a real world use case of Kubernetes, on your local machine!

Requirements:

1. VirtualBox
2. Vagrant on our machine.

May God help you if you have less than 4GB of RAM.

For Kubernetes version 1.24+

Provisioning VMs with all necessary tools

$ git clone https://github.com/mosesmbadi/k8s-local-lab.git
$ cd k8s-local-lab
$ vagrant up
$ vagrant reload

Initializing control plane node

After all VMs are provisioned, follow this guide to setup our cluster:

$ vagrant ssh master
$ sudo kubeadm init --apiserver-advertise-address=192.168.56.10 --pod-network-cidr=10.244.0.0/16

Note the token gotten after the above command

$ mkdir -p $HOME/.kube
$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
$ sudo chown $(id -u):$(id -g) $HOME/.kube/config

Let's configure Calico for networking:

$ kubectl create -f https://raw.githubusercontent.com/projectcalico/calico/v3.27.0/manifests/tigera-operator.yaml
$ kubectl create -f ./shared/helpers/custom-resources.yaml

Joining worker nodes

$ vagrant ssh node1
$ sudo kubeadm join 192.168.56.10:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>

We've typed the join command here, but the join command can also be found after running the kubeadm init. If you didn't copy it, you can find it again by running the following commands on the master node:

$ kubeadm token list
$ openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | \
   openssl rsa -pubin -outform der 2>/dev/null | \
   openssl dgst -sha256 -hex | sed 's/^.* //'

If for some reason you cant find the token, you can regenerate with

$ kubeadm token create --ttl 8760h

Run the same join command on each worker node.

Now we should have a 3-node Kubernetes cluster running on our local machine. here are some commands you can start with:

$ vagrant ssh master
$ kubectl get node -o wide

$ kubectl cluster-info

$ kubectl get all --all-namespaces

Kubernetes Dashboard

NB: I will get back to this later.

Next Steps

Open the Kubernetes Pocket Guide from ./learning-resources and let the games begin...

If you appreciate free education, feel free to make a donation

Let's deploy an application

kubectl apply -f ./shared/manifests/manifests

Get more info about a pod or cluster activities

kubectl get pods
kubectl describe pod <pod-name>
kubectl get events --all-namespaces --field-selector type=Warning
kubectl get events -w

Exec into a container

kubectl exec -it <pod-name> -c <container-name> -- /bin/bash

To access your application outside the cluster kubectl get service -n easymed`` This will show you the port the application is running on, assuming you used a NodePort in your service definition You can then access your application with :port```

To read logs kubectl logs -l app=easymed-api -n easymed

======================== Troubleshooting Confirm all scripts ran - by running them manually If your kubelet is stuck here Active: activating(auto-restart)

type sudo swapoff -a on each node

If that doesnt work, check kubelet logs sudo journalctl -u kubelet -n 100 --no-pager That might help you identify the issue

If still facing errors destroy the machines then rebuild without scripts vagrant destroy -f vagrant up

then run the scripts manually in the order shown below

disable-swap.sh
install-essential-tools.sh
scripts/allow-bridge-nf-traffic.sh
scripts/install-containerd.sh
scripts/install-kubeadm.sh
scripts/update-kubelet-config.sh

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