Kubernetes Cluster using Virtual Box

This is a quick and basic setup for a single-master, duo worker node Kubernetes cluster using VirtualBox to virtualize the nodes. The setup uses vagrant to quickly pull VM images (Ubuntu/Focal64) and bootstraps the nodes, installing docker, kubelet, kubectl, kubeadm and the Calico CNI. This is tested for K8s 1.24.0 and kubectl 1.24.0.

Requirements

• Windows (amd64) Host Machine
• Vagrant(>=2.2.19): To quickly provision and bootstrap the nodes
• VirtualBox(>=6.1.30): For virtualization of the nodes
• Kubernetes (>=1.24.0): Tested on this version
• >= 2 CPUs and >= 2 GB RAM per node (configurable in Vagrantfile)
• Each node must have a unique private IP and hostname on the VirtualBox host network. (configurable in Vagrantfile under the key config.vm.network and config.vm.provision respectively)
• The K8s cluster uses the Calico as a node networking solution.

Usage

1. Ensure that the VirtualBox UI is running.
2. Go to ./kube-master and run vagrant up
3. Ensure that the kube-master node is properly setup by running kubectl get nodes and kubectl get pods --all-namespaces, all pods should show 1/1 and the master node should be READY.
4. Retrieve the following command using sudo cat /kubeadm.log in the kube-master's directory. Ensure that sudo is present when running it on the worker node VMs (steps 5,7).

sudo kubeadm join <NODE_IP>:6443 --token <TOKEN> \
        --discovery-token-ca-cert-hash sha256:<HASH>

5. Go to ./kube-w1 and run vagrant up
6. Run the command from step 4.
7. Go to ./kube-w2 and run vagrant up
8. Run the command from step 4.
9. Go back to kube-master and run kubectl get nodes, all 3 nodes should show as READY

Default credentials

The vagrant default credentials for the vm are vagrant:vagrant. This can be configured in the Vagrantfile. Refer to the Vagrant documentation.

To use custom SSH Key for the VMs (Optional)

The script will look out for ./id_rsa.pub in the root directory. If present, the SSH key will be uploaded to all of the nodes.

The id_rsa.pub is git ignored and will need to be defined after cloning.

Bootstrap Script Args

The kube installation script runs when the VM is provisioned and first started up and is called bootstrap-kube-xx.sh. The bash script takes in 2 positional arguments.

1. The hostname to set for the node
2. The kubernetes version to install ( 1.24.0 | x.x.x )