This a project which could be used it as playground to learn and experiment with Kubernetes, especially for on-premise installations.
The code is just for fun and learning, do not use for production. Minimum 8 GB of RAM but 16 GB of RAM are recommended.
Vagrant with Virtualbox as provider will be used to create the infrastructure. One server will the Kubernetes master and two servers as Kubernetes workers. The virtual machines will run Ubuntu 16.04 (xenial).
Start up the infrastructure:
$ vagrant up
If any change is desired, you only have to modify Vagrantfile.
Ansible is the chosen tool to install all the necessary software in the servers to have Kubernetes ready.
Several Roles have been developed to help us:
- docker: It will install docker in all the servers
- kubernetes-common: Common parts for Kubernetes installation which have to be installed in all the servers (masters and workers).
- kubernetes-master: It will initialize Kubernetes master, install a CNI plugin (Flannel in this case), or produce the code for the nodes to join the cluster.
- kubernetes-worker: It will help the nodes to join the cluster.
$ ansible-playbook k8s.ymlThe Ansible Playbook finishes with a task which will create a file called mykubeconfig which should be used to work with the just created kubernetes cluster through the tool kubectl
Example:
$ kubectl get nodes -o wide --kubeconfig mykubeconfig
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k8s1 Ready master 1m v1.13.5 192.168.33.11 <none> Ubuntu 16.04.6 LTS 4.4.0-151-generic docker://18.6.1
k8s2 Ready <none> 57s v1.13.5 192.168.33.21 <none> Ubuntu 16.04.6 LTS 4.4.0-151-generic docker://18.6.1
k8s3 Ready <none> 57s v1.13.5 192.168.33.22 <none> Ubuntu 16.04.6 LTS 4.4.0-151-generic docker://18.6.1
$ kubectl run nginx --port=80 --image=nginx --replicas=2 --kubeconfig mykubeconfig
$ kubectl expose deployment nginx --port=80 --type=NodePort --kubeconfig mykubeconfig
$ kubectl run httpd --port=80 --image=httpd --replicas=2 --kubeconfig mykubeconfig
$ kubectl expose deployment httpd --port=80 --type=NodePort --kubeconfig mykubeconfig
Check out the assigned Ports.
kubectl get svc --kubeconfig mykubeconfig
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
httpd NodePort 10.103.208.92 <none> 80:30275/TCP 18s
nginx NodePort 10.105.235.99 <none> 80:32741/TCP 70s
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 8m
Make requests to any of the nodes
$ curl 192.168.33.21:32741
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
body {
width: 35em;
margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif;
}
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
$ curl 192.168.33.21:30275
<html><body><h1>It works!</h1></body></html>
The servers only have private IPs, therefore it would not be possible to access to the applications from other computers. Let's solve it !!