[GUIDE] Running MicroK8s & Nginx-ingress on CentOS 7

The goal of this guide is to help you get a single-machine Kubernetes cluster up and running. The cluster will be exposed to outside connections through Nginx-ingress. An Ingress and a Service will be created to send traffic to a Deployment running a Hello World NodeJS application. So, if you ever wanted to run your personal website on k8s without a hitch this guide is your go-to.

The guide is meant to be hands-on and no-nonsense. I won’t go into too much, if any, detail about individual components and I will assume you’re familiar with the following:

• CentOS 7
• Snap
• Docker
• Kubernetes
• MicroK8s
• Nginx
• Nginx-ingress
• NodeJS
• DNS

NOTE: You can follow along on a different Linux distro or even Windows. I‘ve added references to installation guides at the bottom of each section where applicable. Windows users should skip to the Kubernetes section. I have not attempted installation on a OS other than CentOS 7 & 8. The attempt on CentOS 8 was unsuccessful due to a failure to install snap .

Pre-requistes

You have:

• Access to a machine running CentOS 7.
• Root access to that machine.
• A Fully Qualified Domain Name at your disposal.

CentOS 7

Snap

We’ll need snap to install MicroK8s. So lets install it.

• Login to your CentOS machine as root
• Run these commands to install snap and enable backwards compatibility with classic snaps:

yum install snapd
systemctl enable --now snapd.socket
ln -s /var/lib/snapd/snap /snap

• Restart your CentOS instance or start a new terminal session. This allows the snapd binaries to be loaded.
• IMPORTANT: Do not prepend sudo to the snapdinstallation commands. Follow this link to find out why.

Linux distros: Follow the instructions on this page to install snap for your specific distro.

Kubernetes

MicroK8s

We’ll need MicroK8s so we can run your personal website.

• Run these commands to install MicroK8s:

snap install microk8s --classic --channel=1.16/stable
microk8s.status --wait-ready

Windows: You will need multipass to install MicroK8s. Go to this page, follow the instructions and install multipass on Windows. When you’re done installing multipass, go to this page, scroll down until you see the Windows logo, click the logo and follow the instructions.

Nginx Ingress

To expose your Kubernetes cluster to the big, bad outside world we’ll need another piece of software. Kubernetes has a concept called an Ingress to do this. A standalone installation of Nginx could perform the same job in a non-Kubernetes system. So, lets have a divine union and use Nginx-ingress in your cluster.

• Run these commands to, alias microk8s.kubectl, enable install Nginx-ingress

sudo snap alias microk8s.kubectl kubectl
microk8s.enable ingress
kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/mandatory.yaml

Windows: If-and-only-if you’ve installed multipass you can follow the commands above.

Creating the necessary objects

Now that your Kubernetes cluster is ready, lets deploy your personal website. First we’ll deploy the NodeJS server hosting the website.

IMPORTANT: All of the files below contain a example.com string-value. Replace that string with the actual domain-name of your own personal-website.com. You should also replace the image heroku/nodejs-hello-world with an image containing your web-application.

• Create a file named deployment.yml and edit its content to equal the following:

apiVersion: apps/v1
kind: Deployment
metadata:
name: personal-website-deployment
labels:
uri: example.com
spec:
selector:
matchLabels:
uri: example.com
template:
metadata:
labels:
uri: example.com
spec:
containers:

    - name: personal-website  
      image: heroku/nodejs-hello-world  
      ports:  
        - containerPort: 5000

• Create a file named service.yml and edit its content to equal the following:

apiVersion: v1
kind: Service
metadata:
name: personal-website-service
spec:
selector:
uri: example.com
type: ClusterIP
ports:

- name: http  
  protocol: TCP  
  port: 80  
  targetPort: 5000

• Create a file named ingress.yml and edit its content to equal the following:

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: personal-website-ingress
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
spec:
rules:

- host: example.com  
  http:  
    paths:  
      - backend:  
          serviceName: personal-website-service  
          servicePort: 80

• Now run the following command to create the Kubernetes Objects necessary for your application.

kubectl create -f deployment.yml -f service.yml -f ingress.yml

Networking

DNS

This guide assumes following DNS prerequisites.

• You own a domain-name.
• You’ve setup an A- or AAAA-record that refers to the IP-adress of your CentOS-machine.

Localhost

If you do not want to proxy traffic from example.com and you just want to fiddle around locally. Removing the hostkey from the rules map in the ingress.yml file should do the trick. I’ve only tested the DNS settings mentioned above so I cannot ensure it will.

Aaaaand boom goes the dynamite! Liked this post? Clap. Disliked this post? Comment. Have something interesting to add or have I missed something? Comment! I’ll always consider any of your suggestions and/or improvements.