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Learning Kubernetes

Auto-K8s is an automation setup for Kubernetes cluster environment using Vagrant and Virtualbox. Ansible is used to automate Kubernetes features. This is a minimal setup to facilitate learning, development and usage of Kubernetes platform for container cluster management.

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development, learning and testing purposes.

Prerequisites

You will require the following to be available in your local machine to be able to proceed with the project

Do not worry if you know nothing about the pre-requisites. You can follow Getting Started with Vagrant and VirtualBox to learn more about them.

Note: It is recommended to use latest version of Vagrant i.e. >= 1.8.7, as earlier versions had issues with Ansible 2.0. I used the following versions:

Vagrant version 1.8.7

VirtualBox Version 5.1.22

Installation and setup

A step by step approach that will get you a Kubernetes env running.

  1. First clone the project to your local machine.
>> git clone [email protected]:naikajah/auto-k8s.git
>> cd auto-k8s
  1. You will now create Kubernetes master or controller node. Details about Kubernetes master/controller node is explained in detail here.
>> vagrant up k8s-master

Wait for the master/controller to be up. Once the master/controller is active, verify that the following services are up and running. More about these services here.

>> vagrant ssh k8s-master
>> sudo systemctl status etcd kube-apiserver kube-controller-manager kube-scheduler | grep Active

All these services should be in a running state.

[root@kube-master vagrant]# systemctl status etcd kube-apiserver kube-controller-manager kube-scheduler | grep Active
   Active: active (running) since Thu 2017-07-20 19:51:07 CEST; 1min 31s ago
   Active: active (running) since Thu 2017-07-20 19:51:07 CEST; 1min 30s ago
   Active: active (running) since Thu 2017-07-20 19:51:08 CEST; 1min 30s ago
   Active: active (running) since Thu 2017-07-20 19:51:08 CEST; 1min 30s ago
  1. Now since we got the kubernetes master/controller healthy, wealthy and wise, its time to bring pretty minions up. More on minions here.

Start a new terminal window for minions.

>> vagrant up k8s-minion1

Wait for the first minion to be up. Once the minion is active, verify that the following services are up and running. More about these services here.

>> vagrant ssh k8s-minion1
>> sudo systemctl status kube-proxy kubelet docker | grep Active

All these services should be in a running state.

[root@kube-minion1 vagrant]# systemctl status kube-proxy kubelet docker | grep Active
   Active: active (running) since Thu 2017-07-20 19:55:07 CEST; 9min ago
   Active: active (running) since Thu 2017-07-20 20:04:42 CEST; 9min ago
   Active: active (running) since Thu 2017-07-20 19:55:09 CEST; 9min ago

Now the Kubernetes is configured and ready to be explored.

Verifying the Kubernetes setup

ssh to k8s-master and execute the following to verify if the minion1 is registered to it

>> kubectl get nodes

If minion1 has registered itself properly with the master/controller then you should see the following output

[root@kube-master vagrant]# kubectl get nodes
NAME           STATUS    AGE
kube-minion1   Ready     10m

Similarly you can bring up k8s-minion2 and k8s-minion3 up depending on the resources available in your machine. You can also configure the memory and vcpu requirements in the nodes.yaml file here.

WELL DONE!!!!!! You have successfully configured Kubernetes.

Setting up your first POD

A POD in Kubernetes is a group of one or more containers.

As part of this automation a minimal POD yaml configuration is provided at /opt/development directory in master/controller server.

In order to start with POD, execute the below commands to get your first POD running

>> vagrant ssh k8s-master
>> cd /opt/development
>> [root@kube-master development]# kubectl create -f ./pod_nginx.yaml
pod "nginx" created

>> [root@kube-master development]# kubectl get pods
NAME      READY     STATUS    RESTARTS   AGE
nginx     1/1       Running   0          46s

In order to verify our POD, execute the below command

>> kubectl describe pod nginx

This will show the detail information about the POD and and its containers.

[root@kube-master development]# kubectl describe pod nginx
Name:		nginx
Namespace:	default
Node:		kube-minion1/192.168.1.25
Start Time:	Thu, 20 Jul 2017 20:31:43 +0200
Labels:		<none>
Status:		Running
IP:		172.17.0.2
Controllers:	<none>
Containers:
  nginx:
    Container ID:	docker://e256f15080b68476ebf4afe7006f5a562b2b82256c8f823bf5fb746208ed5416
    Image:		nginx:1.7.9
    Image ID:		docker-pullable://docker.io/nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
    Port:		80/TCP
    State:		Running
      Started:		Thu, 20 Jul 2017 20:32:00 +0200
    Ready:		True
    Restart Count:	0
    Volume Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-mvvl7 (ro)
    Environment Variables:	<none>

In order to see the running containers. Connect to the minion associated with the POD.

>> vagrant ssh k8s-minion1
[root@kube-minion1 vagrant]# docker ps
CONTAINER ID        IMAGE                                      COMMAND                  CREATED             STATUS              PORTS               NAMES
e256f15080b6        nginx:1.7.9                                "nginx -g 'daemon off"   6 minutes ago       Up 6 minutes                            k8s_nginx.f80b328f_nginx_default_ae1256bf-6d79-11e7-a2cf-08002775ff5f_de324289
4c514a0ee6ea        gcr.io/google_containers/pause-amd64:3.0   "/pause"                 6 minutes ago       Up 6 minutes                            k8s_POD.b2390301_nginx_default_ae1256bf-6d79-11e7-a2cf-08002775ff5f_39470741

WELL DONE!!!! again.

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