introduction-to-helm

Installing Helm

https://helm.sh/docs/intro/install/

Check the kubernetes cluster context helm is connecting to

kubectl config get-contexts

Search for helm charts in Artifact hub

https://artifacthub.io/

Search for helm charts using Helm CLI

helm search hub ingress-nginx

helm search repo ingress-nginx

Install Nginx ingress controller

Add repo:

helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx

helm repo update

helm search repo ingress-nginx

Install chart:

helm install [RELEASE_NAME] [REPO_NAME]/[CHART_NAME]  [FLAGS]

helm install ingress-nginx ingress-nginx/ingress-nginx --namespace ingress-basic --create-namespace

List the installed chart:

helm ls -n ingress-basic 

View the kubernetes resources created:

kubectl get all -n ingress-basic
kubectl get svc -n ingress-basic
kubectl describe cm ingress-nginx-controller -n ingress-basic

Upgrade the release using --set flag

kubectl get pods -n ingress-basic

helm upgrade ingress-nginx ingress-nginx/ingress-nginx -n ingress-basic --set controller.replicaCount=2

kubectl get pods -n ingress-basic

Rollback the release back to the previous version

helm rollback ingress-nginx 1 -n ingress-basic 

Check the history of the release:

helm history ingress-nginx -n ingress-basic

Uninstall ingress controller

helm uninstall ingress-nginx -n ingress-basic

Install the helm chart with custom values file

helm upgrade ingress-nginx ingress-nginx/ingress-nginx \
    --install \
    --namespace ingress-basic \
    --create-namespace \
    --values values-ic.yaml

Some other flags that can be used with helm install :

    --wait       
    --debug
    --timeout 10m0s

Deploy aspnetapp using yaml files

kubectl create ns test

kubectl apply -f deployment.yaml -n test
kubectl apply -f service.yaml -n test
kubectl apply -f ingress.yaml -n test

Commands that'll be useful while creating your own helm chart

Create a helm chart:

 helm create aspnetapp

Examine a helm chart for possible issues:

 helm lint ./aspnetapp

Render the helm chart templates locally and save it to a yaml file:

helm template aspnetapp --debug > test.yaml

Install the created chart:

helm install aspnetapp ./aspnetapp -n test 

Notes

Helm install resources to the k8s cluster in a particular order:

https://helm.sh/docs/intro/using_helm/#helm-install-installing-a-package

Docker image used as dmctest.azurecr.io/aspnetapp:latest for the demo:

mcr.microsoft.com/dotnet/samples:aspnetapp

Built-in objects of helm : https://helm.sh/docs/chart_template_guide/builtin_objects/

Template function list : https://helm.sh/docs/chart_template_guide/function_list/