A simple demo to setup Kubernetes on bare-metal (and also on VM via Vagrant.

Requirements

• Ubuntu 18.04.1 LTS (Bionic Beaver). The Vagrantfile is based on this distribution.
• Ansible

For VMs we need:

• Vagrant
• vagrant-rsync-back to obtain the KUBECONFIG file from the master node.

$ vagrant plugin install vagrant-rsync-back

Setup

Provisioning

Bare-metal

Execute Ansible playbook to provision the machine.

cd ansible
export PRIV_KEY=""
ansible-playbook --diff --check -vv provision.yml --private-key="${PRIV_KEY}" --ask-become-pass

VM

Use Vagrant.

cd vagrant
vagrant up

Initialize the Kubernetes master for both bare-metal and VM.

1. SSH into the master node and setup Kubernetes master with kubeadm.

# export IP_ADDR="" # For Vagrant, this should be 192.168.50.110
# kubeadm init --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address="${IP_ADDR}"

2. Copy the /etc/kubernetes/admin.conf file and use that with kubectl to talk with kubernetes. We can use the KUBECONFIG environment variable for this. For Vagrant this can be done with:

# cp -i /etc/kubernetes/admin.conf /vagrant/config
# chown vagrant:vagrant /vagrant/config

On the host, run the follwing under the vagrant/ directory to copy the config file to host

$ vagrant rsync-back
$ ls kubernetes
config

Install networking.

For bare-metal:

$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/bc79dd1505b0c8681ece4de4c0d86c5cd2643275/Documentation/kube-flannel.yml

For Vagrant's VM use the kube-flannel.yml in the vagrant/ directory.

$ kubectl apply -f kube-flannel.yml

Setting up single-host cluster.

Taint the master node so that we can use the master as single-host cluster.

$ kubectl taint nodes --all node-role.kubernetes.io/master-

Adding worker node to cluster.

When we have more machines to join the the cluster, we can generate the join command within the master node and use the resulting kubeadm join command in the worker node to add it into the cluster.

# kubeadm token create --print-join-command
kubeadm join <IP-ADDR> --token <SECRET> --discovery-token-ca-cert-hash <HASH>

References

• A. Ellis, Kubernetes on bare-metal in 10 minutes
• A. Ellis, Your instant Kubernetes cluster
• Creating a single master cluster with kubeadm