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kubernetes-training

This repository provides some infrastructure code based on Vagrant & Virtualbox to get a basic infrastructure useable for the LFS258 Kubernetes fundamentals training.

Prerequisites

  • Vagrant
  • Virtualbox
  • Bridge networking: we use public networking to expose Kubernetes API Server

This setup was used on a Macos based workstation. I believe the Vagrant part of this repository will work fine on any machine that support Virtualbox & Vagrant.

Configuration

As of now there is few configuration options available except:

  • configure the number of Kubernetes worker you want to have. Default: 1
  • configure the network interface that will be used as a bridge.
    • The default value suits my personal rig: there are good chances that you need to update this configuration.

Those options are set in the Vagrantfile directly.

Usage

Spin up a local infrastructure for the training

You can use the following make target to start the whole infrastructure.

# Spin up the nodes
make init

# Snapshot Kubernetes master in case of
make save snapshot=before-kubeadm

Connect to the instances

You can connect to the instances through the following commands:

  • Kubernetes master node: vagrant ssh kube-master
  • Kubernetes worker node: vagrant ssh kube-worker-1
  • If you asked for more workers they will be available using the same pattern as for the previous worker
    • e.g.: kube-worker-2, ...

Creating the cluster

The Kubernetes fundamentals training will guide through the usage of kubeadm so I won't tell that much about it.

Note that sometimes kubeadm init will pick the wrong network interface & bind Kubernetes API server to the NAT interface 10.0.2.15.

If this happens:

  • Reset the master node by either:
    • sudo kubeadm reset
    • or use the make target make restore snapshot=before-kubeadm
  • Fetch your public IP out of ip addr. This one should be set on the eth1 interface
  • Use the --apiserver-advertise-address option during kubeadm init

After establishing the cluster:

  • make sure that you follow kubeadm instructions to move the Kubernetes config file to your user inside the Kubernetes master node
  • create a snapshot for Kubernetes master: it could help you later if you screw up
    • make save snapshot=after-kubeadm

Fetch the Kubernetes config file for local usage

You can use the following commands in order to use your own terminal/shell to work with this cluster

Note: you must have followed kubeadm instructions about moving the Kubernetes configuration file to the user home.

vagrant ssh-config > /tmp/vagrant.ssh
scp -F /tmp/vagrant.ssh kube-master:~/.kube/config /tmp/vagrant.kube.config
rm /tmp/vagrant.ssh

export KUBECONFIG=/tmp/vagrant.kube.config

Restore Kubernetes master

If by any chance you wreck your Kubernetes cluster you can restore the Kubernetes nodes back to a previous snapshot: make restore snapshot=after-kubeadm-init.

This example restores back to the moment you have just established the cluster though you can create more snapshots whenever you want to.

As for the workers: you can simply kill them &

Tear down the infrastructure

When you don't need it anymore:make tear-down