helm-demo.md

Helm demo

This demo will user the ingress on bare-metal using the Nginx Ingress Controller and metalLB.

In my helm-demo folder, I have the templates directory and the Chart and values YAML files :

k8s-master@master:~/helm-demo$ ls
Chart.yaml  templates  values.yaml

Inside the Chart.yaml file :

name: my-first-demo
version: 1.0.0
description: easy helm demo
maintainers:
- name: Siwar

This is the metadata to describe each deployment.

Now inside the templates directory :

k8s-master@master:~/helm-demo/templates$ ls
deployment.yaml  ingress.yaml  service.yaml

The depoyment.yaml file contains a simple nginx deployment :

apiVersion: apps/v1
kind: Deployment
metadata: 
  name: my-nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 3
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

And the service.yaml file :

apiVersion: v1
kind: Service
metadata: 
  name: my-nginx-service
spec:
  selector:
    app: nginx
  ports:
  - name: main
    protocol: TCP
    port: 80

And the ingress.yaml :

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-nginx-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
    http.port: "443"
spec:
  ingressClassName: nginx
  rules:
  - http:
      paths:
      - path: /testpath
        pathType: Prefix
        backend:
          service:
            name: my-nginx-service
            port:
              number: 80

We're exposing port 443 on our ingress.

Next is helm install:

k8s-master@master:~$ helm install --generate-name helm-demo/
NAME: helm-demo-1660310990
LAST DEPLOYED: Fri Aug 12 06:29:50 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None

So now with Helm and thanks to only one command line tool helm install, we were able to deploy our app very easily and very fast.

k8s-master@master:~$ kubectl get all
NAME                                      READY   STATUS              RESTARTS   AGE
pod/my-nginx-deployment-9456bbbf9-c74rs   0/1     ContainerCreating   0          11s
pod/my-nginx-deployment-9456bbbf9-k4cdb   0/1     ContainerCreating   0          11s
pod/my-nginx-deployment-9456bbbf9-mm7dm   0/1     ContainerCreating   0          11s

NAME                       TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
service/kubernetes         ClusterIP   10.96.0.1        <none>        443/TCP   22m
service/my-nginx-service   ClusterIP   10.100.146.193   <none>        80/TCP    11s

NAME                                  READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/my-nginx-deployment   0/3     3            0           11s

NAME                                            DESIRED   CURRENT   READY   AGE
replicaset.apps/my-nginx-deployment-9456bbbf9   3         3         0       11s

We can check our app running in the browser using the ingress ip 192.168.1.240 and specifying the path /testpath:

The usual way to do this with kubectl is by executing the kubectl apply command line for every resource.

Another important feature in Helm are placeholders! so if we look at another deployment.yaml file for example :

apiVersion: apps/v1
kind: Deployment
metadata: 
  name: my-nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: {{.Values.scale}}
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

The {{.Values.scale}}placeholder makes it possible to modify the configuration without having to edit the actual manifest file every time.

So whatever the value of scale is in values.yaml file is going to be the value of the configuration file.

The values.yaml file :

k8s-master@master:~/helming-once-more$ cat values.yaml
scale: 3

And now let's install our app again :

k8s-master@master:~$ helm install another-demo helming-once-more/
NAME: another-demo
LAST DEPLOYED: Fri Aug 12 11:48:53 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None

Just to check that we have our pods up and running :

k8s-master@master:~$ kubectl get pods
NAME                                  READY   STATUS    RESTARTS   AGE
my-nginx-deployment-9456bbbf9-mx45n   1/1     Running   0          3m9s
my-nginx-deployment-9456bbbf9-rqkmw   1/1     Running   0          3m9s
my-nginx-deployment-9456bbbf9-tl4wj   1/1     Running   0          3m9s

So thanks to the scale value in the values.yaml file, we now have 3 pods.

For some reason or another, we needed to scale up our up :

k8s-master@master:~$ helm upgrade --set scale=5 another-demo ./helming-once-more/
Release "another-demo" has been upgraded. Happy Helming!
NAME: another-demo
LAST DEPLOYED: Fri Aug 12 11:55:14 2022
NAMESPACE: default
STATUS: deployed
REVISION: 2
TEST SUITE: None

k8s-master@master:~$ kubectl get pod
NAME                                  READY   STATUS    RESTARTS   AGE
my-nginx-deployment-9456bbbf9-7ddlm   1/1     Running   0          95s
my-nginx-deployment-9456bbbf9-mx45n   1/1     Running   0          8m9s
my-nginx-deployment-9456bbbf9-rqkmw   1/1     Running   0          8m9s
my-nginx-deployment-9456bbbf9-tl4wj   1/1     Running   0          8m9s
my-nginx-deployment-9456bbbf9-tpsqv   1/1     Running   0          96s

To finish off, we will delete our app :

k8s-master@master:~$ helm list
NAME           NAMESPACE       REVISION        UPDATED                                 STATUS          CHART                   APP VERSION
another-demo    default         2               2022-08-12 11:55:14.913503686 -0700 PDT deployed        another-demo-1.0.0
k8s-master@master:~$ helm uninstall another-demo
release "another-demo" uninstalled