blog.lazkani.io-20200902-historical/posts/kubernetes/local_kubernetes_cluster_on_kvm.rst

.. title: Local Kubernetes Cluster on KVM
.. date: 2019-02-17
.. updated: 2019-06-21
.. status: published
.. tags: kubernetes, rancher, rancheros, kvm, libvirt,
.. category: kubernetes
.. slug: local-kubernetes-cluster-on-kvm
.. authors: Elia el Lazkani
.. description: Deploying a kubernetes cluster locally on KVM.
.. type: text


I wanted to explore *kubernetes* even more for myself and for this blog. I've worked on pieces of this at work but not the totality of the work which I would like to understand for myself. I wanted, also to explore new tools and ways to leverage the power of *kubernetes*.

So far, I have been using *minikube* to do the deployments but there is an inherit restriction that comes with using a single bundled node. Sure, it is easy to get it up and running but at some point I had to use ``nodePort`` to go around the IP restriction. This is a restriction that you will have in an actual *kubernetes* cluster but I will show you later how to go around it. For now, let's just get a local cluster up and running.

.. TEASER_END

Objective
=========

I needed a local *kubernetes* cluster using all open source tools and easy to deploy. So I went with using *KVM* as the hypervisor layer and installed ``virt-manager`` for shallow management. As an OS, I wanted something light and made for *kubernetes*. As I already know of Rancher (being an easy way to deploy *kubernetes* and they have done a great job so far since the launch of their Rancer 2.0) I decided to try *RancherOS*. So let's see how all that works together.

Requirements
============

Let's start by thinking about what we actually need. Rancher, the dashboard they offer is going to need a VM by itself and they `recommend <https://rancher.com/docs/rancher/v2.x/en/quick-start-guide/deployment/quickstart-vagrant/>`_ *4GB of RAM*. I only have *16GB of RAM* on my machine so I'll have to do the math to see how much I can afford to give this *dashboard* and *manager*. By looking at the *RancherOS* hardware `requirements <https://rancher.com/docs/os/v1.x/en/>`_, I can tell that by giving a each node *2GB* of RAM I should be able to host a *3 node cluster* and with *2* more for the *dashboard* that puts me right on *8GB of RAM*. So we need to create *4 VMs* with *2GB of RAM* each.

Installing RancherOS
====================

Once all 4 nodes have been created, when you boot into the *RancherOS* `ISO <https://rancher.com/docs/os/v1.x/en/installation/running-rancheros/workstation/boot-from-iso/>`_ do the following.

.. note::

    Because I was using *libvirt*, I was able to do ``virsh console <vm>`` and run these commands.

Virsh Console
=============

If you are running these VMs on *libvirt*, then you can console into the box and run ``vi``.

.. code:: text

  # virsh list
  Id   Name      State
  -------------------------
  21   kube01    running
  22   kube02    running
  23   kube03    running
  24   rancher   running

  # virsh console rancher

Configuration
=============

If you read the *RancherOS* `documentation <https://rancher.com/docs/os/v1.x/en/>`_, you'll find out that you can configure the *OS* with a ``YAML`` configuration file so let's do that.

.. code:: text

   $ vi cloud-config.yml

And that file should hold.

.. code:: yaml

   ---
   hostname: rancher.kube.loco
   ssh_authorized_keys:
     - ssh-rsa AAA...
   rancher:
     network:
       interfaces:
         eth0:
           address: 192.168.122.5/24
           dhcp: false
           gateway: 192.168.122.1
           mtu: 1500

Make sure that your **public** *ssh key* is replaced in the example before and if you have a different network configuration for your VMs, change the network configuration here.

After you save that file, install the *OS*.

.. code:: text

   $ sudo ros install -c cloud-config.yml -d /dev/sda

Do the same for the rest of the servers and their names and IPs should be as follows (if you are following this tutorial):

.. code:: text

   192.168.122.5   rancher.kube.loco
   192.168.122.10  kube01.kube.loco
   192.168.122.11  kube02.kube.loco
   192.168.122.12  kube03.kube.loco

Post Installation Configuration
===============================

After *RancherOS* has been installed, one will need to configure ``/etc/hosts`` and it should look like the following if one is working off of the *Rancher* box.

.. code:: text

  $ sudo vi /etc/hosts

.. code:: text

   127.0.0.1       rancher.kube.loco
   192.168.122.5   rancher.kube.loco
   192.168.122.10  kube01.kube.loco
   192.168.122.11  kube02.kube.loco
   192.168.122.12  kube03.kube.loco

Do the same on the rest of the servers while changing the ``127.0.0.1`` hostname to the host of the server.

Installing Rancher
==================

At this point, I have to stress a few facts:

- This is not the Rancher recommended way to deploy *kubernetes*.

  - The recommended way is of course `RKE <https://rancher.com/docs/rke/v0.1.x/en/>`_.

- This is for testing, so I did not take into consideration backup of anything.

  - There are ways to backup Rancher configuration by mounting storage from the ``rancher`` docker container.

If those points are understood, let's go ahead and deploy Rancher.
First, ``$ ssh rancher@192.168.122.5`` then:

.. code:: text

   [rancher@rancher ~]$ docker run -d --restart=unless-stopped -p 80:80 -p 443:443 rancher/rancher

Give it a few minutes for the container to come up and the application as well. Meanwhile configure your ``/etc/hosts`` file on your machine.

.. code:: text

   192.168.122.5    rancher.kube.loco

Now that all that is out of the way, you can login to https://rancher.kube.loco and set your ``admin`` password and the ``url`` for Rancher.

Deploying Kubernetes
====================

Now that everything is ready, let's deploy *kubernetes* the easy way.

At this point you should be greeted with a page that looks like the following.

.. thumbnail:: /images/local_kubernetes_cluster_on_kvm/01-add_cluster.png
    :align: center
    :alt: Add Cluster Page


Click on the **Add Cluser**


.. thumbnail:: /images/local_kubernetes_cluster_on_kvm/02-custom_cluster.png
    :align: center
    :alt: Custom Cluster Page


Make sure you choose **Custom** as a *provider*. Then fill in the **Cluser Name** in our case we'll call it **kube**.


.. thumbnail:: /images/local_kubernetes_cluster_on_kvm/03-calico_networkProvider.png
    :align: center
    :alt: Network Provider: Calico (Optional)


Optionally, you can choose your **Network Providor**, in my case I chose **Calico**. Then I clicked on **show advanced** at the bottom right corner then expanded the *newly shown tab* **Advanced Cluster Options**.


.. thumbnail:: /images/local_kubernetes_cluster_on_kvm/04-nginx_ingressDisabled.png
    :align: center
    :alt: Nginx Ingress: Disabled


We will disable the **Nginx Ingress** and the **Pod Security Policy Support** for the time being. This will become more apparent why in the future, hopefully. Then hit **Next**.


.. thumbnail:: /images/local_kubernetes_cluster_on_kvm/05-customer_nodes.png
    :align: center
    :alt: Customize Nodes


Make sure that you select all **3 Node Roles**. Set the **Public Address** and the **Node Name** to the first node and then copy the command and paste it on the *first* node.

Do the same for *all the rest*. Once the first docker image gets downloaded and ran you should see a message pop at the bottom.


.. thumbnail:: /images/local_kubernetes_cluster_on_kvm/06-registered_nodes.png
    :align: center
    :alt: Registered Nodes


.. warning::

   Do **NOT** click *done* until you see all *3 nodes registered*.


Finalizing
==========

Now that you have *3 registered nodes*, click **Done** and go grab yourself a cup of coffee. Maybe take a long walk, this will take time. Or if you are curious like me, you'd be looking at the logs, checking the containers in a quad pane ``tmux`` session.

After a long time has passed, our story ends with a refresh and a welcome with this page.

.. thumbnail:: /images/local_kubernetes_cluster_on_kvm/07-kubernetes_cluster.png
    :align: center
    :alt: Kubernetes Cluster


Welcome to your Kubernetes Cluster.

Conclusion
==========

At this point, you can check that all the nodes are healthy and you got yourself a kubernetes cluster. In future blog posts we will explore an avenue to deploy *multiple ingress controllers* on the same cluster on the same ``port: 80`` by giving them each an IP external to the cluster.

But for now, you got yourself a kubernetes cluster to play with. Enjoy.