Helm

Create a helm-chart

I will use my publicly available comments app to build a helm-chart. Get the default scaffolding from helm with:

helm create comments

What I changed to begin with:

In Charts.yaml I changed a few:

• appVersion: “53” (so that it matches the tag of the image I want to deploy)
• name: comments
• Description: A Helm chart for the comments stack

In values.yaml:

• replicaCount: 3 (because I have 3 worker nodes on my cluster)
• image.repository: toubivankenoubi/comments (my image is available on docker hub)

Furthermore, some snippets from the values.yaml with a little explanation:

service:
  type: ClusterIP
  port: 8080
  
ingress:
  enabled: true
  className: "nginx"
  annotations: {}
    # kubernetes.io/ingress.class: nginx
    # kubernetes.io/tls-acme: "true"
  hosts:
    - host: k8s-node-1.tobisyurt.local
      paths:
        - path: /comments
          pathType: Prefix

    - host: k8s-node-2.tobisyurt.local
      paths:
        - path: /comments
          pathType: Prefix
    - host: k8s-node-3.tobisyurt.local
      paths:
        - path: /comments
          pathType: Prefix
    - host: tobisyurt.net
      paths:
        - path: /comments
          pathType: Prefix
  tls: []

I only changed the port of the clusterIp service, because I was used to 8080.

In the Ingress I added a lot of hosts. The important one is tobisyurt.net which is the public facing. Because I want to be able to test it locally too, I added my internal(private network) DNS entries for the 3 k8s nodes.

helm dependencies

The comments app is dependent on a mongodb, so we add that to the dependencies in the Chart.yaml:

...

dependencies:
- name: mongodb
  version: "12.15.4"
  repository: "https://registry-2.docker.io/bitnamicharts"

If you deploy this chart as is, it would deploy the subchart mongodb with all its defaults. Normally you need to override some of these values, so that your pods talk to each other properly.

In the values.yml in your main chart you can override values of your subcharts as follows:

... other values of your chart ...

mongodb:
  persistence:
    size: 499Mi
  auth:
    rootPassword: "a password..."

Using the helm chart

Deployed with:

helm install comments-test ./comments -n comments

Uninstalled with:

helm uninstall comments-test -n comments

Test it without deploying it on the cluster (dry run):

helm install --debug --dry-run comments-test ./comments

Upgrade to the latest chart release:

helm upgrade comments-test . -n comments