Master Kubernetes Helm-Charts

Why do we need Helm-Charts ? While we having manifests files ?

Running single-single manifest files is soo boring and dealing with multiple files will be come hard.
Example:
kubectl apply -f deployment.yml
kubectl apply -f configmap.yml
kubectl apply -f secret.yml
kubectl apply -f service.yml

So can we keep all the manifest files in one folder and can trigger one simple command so that manifest file will get deployed ?

This is what helm will do it for you

What is Helm ?

Helm is a package manager for the kubernetes applications and templatize the manifest files.

Helm installation

sudo dnf install helm -y

Helm Structure

Helm Commands

helm install <chart_name> <directory>

This command will run the all manifests files in the templates folder of that particular chart .

helm upgrade <chart_name> -f values-dev.yaml --set service.targetport="80"

This command will run the all manifests files of particular chart and applies the values present in the values-dev.yaml file and sets the service.targetport to 80.
We can change the values form the command line as well.


helm rollback <chart_name>

Rollback to the previous revision

helm rollback <chart_name> 1

Rollback to the 1st version , if we want to rollback to specific version

helm list

Lists the all charts available

helm uninstall <chart_name>

You can delete the all the resources created in the cluster.

helm history <chart_name>

Gives the entire history of the chart and tells you currently which version was running in the cluster.

helm status <chart_name>

shows what all resources created for the last install / upgrade

How Helm works ?

When you enter the helm install cart . then it will check which cluster is currently pointed too ?

Then it underhood converts to the manifest files and does the kubectly apply -f <file_name>

So if we having multiple clusters then how can we change to another ?

kubectl config get-contexts

This command shows the currently which cluster was pointed too

CURRENT   NAME              CLUSTER
*         dev-cluster       dev-cluster
          test-cluster     test-cluster
          prod-cluster     prod-cluster

kubectl config use-context test-cluster

This command points to the dev-cluster

helm install roboshop ./roboshop
--kube-context dev-cluster

You can pass directly in the helm command as well

helm install roboshop ./roboshop
-f values-dev.yaml
--kube-context dev-cluster

You can pass the values-dev.yaml file also

Note:

we should change the appVersion and the version in the chart.yml file while upgrading , because we will have the clear picture on the deployments when we do helm history <chart_name>

GitHub: https://github.com/vija-web/Kubernetes-/tree/master/Helm_Charts

Thank you !
Happy Helming !