Master Helm: Install, Configure, and Deploy Applications on Kubernetes

Overview

Helm is a package manager for Kubernetes that simplifies installing, managing, and uninstalling applications, similar to yum or apt-get on Linux.

Key Concepts

Chart : A Helm package that contains container images, dependencies, and Kubernetes resource definitions required to run an application. It may also include Service definitions.

Release : An instance of a chart running in a Kubernetes cluster. The same chart can be installed multiple times, each installation creating a separate release.

Repository : An HTTP server that stores and serves chart packages and an index file.

helm : The client‑side command‑line tool that communicates with the server component.

tiller : The server‑side component that interacts with the Kubernetes API server on behalf of the helm client.

Architecture

Installing Helm (Client)

Download the desired version from the Helm releases page: https://github.com/helm/helm/releases.

Extract the archive, e.g. tar -zxvf helm-v2.0.0-linux-amd64.tgz.

Move the binary to an executable directory, e.g. mv linux-amd64/helm /usr/local/bin/helm, then verify with helm --help.

Installing Tiller (Server)

Deploy the server component with helm init. By default Helm uses the stable repository https://kubernetes-charts.storage.googleapis.com/index.yaml and the Tiller image gcr.io/kubernetes-helm/tiller:v2.13.1. In regions with restricted access, specify an alternative repository and image:

helm init \
  --tiller-image registry.cn-hangzhou.aliyuncs.com/google_containers/tiller:v2.13.1 \
  --stable-repo-url https://kubernetes.oss-cn-hangzhou.aliyuncs.com/charts

Verify Installation

helm version

The command prints client and server version information, confirming that both components are installed (e.g., v2.13.1).

Common Helm Commands

helm search

– Search charts in repositories. helm fetch – Download a chart locally. helm list – List releases deployed in the cluster. helm status – Show detailed information about a release. helm install – Install a chart. helm inspect – Describe chart contents. helm delete – Remove a release. helm create – Scaffold a new chart. helm package – Package a chart into a compressed archive. helm repo – Manage chart repositories (add, list, remove).

Granting Tiller Access

If the tiller-deploy Deployment lacks a ServiceAccount, create one and bind it to the cluster-admin role, then patch the deployment to use the account:

kubectl create serviceaccount --namespace kube-system tiller
kubectl create clusterrolebinding tiller-cluster-rule \
  --clusterrole=cluster-admin \
  --serviceaccount=kube-system:tiller
kubectl patch deploy --namespace kube-system tiller-deploy \
  -p '{"spec":{"template":{"spec":{"serviceAccount":"tiller"}}}}'

Deploying WordPress with Helm

Install a WordPress instance without persistent storage:

helm install --name wordpress-test \
  --set "persistence.enabled=false,mariadb.persistence.enabled=false" stable/wordpress

Retrieve the service address and the generated admin password:

kubectl get svc -o wide
kubectl get secret --namespace default wordpress-test-wordpress \
  -o jsonpath="{.data.wordpress-password}" | base64 --decode

Open the service URL in a browser and log in with the obtained credentials.

Upgrading a Release

When a new chart version is available or configuration changes are required, use helm upgrade:

helm upgrade wordpress-test \
  --set "persistence.enabled=true,mariadb.persistence.enabled=true" stable/wordpress

References

Helm Official Documentation: https://helm.sh/docs/ Helm Installation Guide (Aliyun):

https://yq.aliyun.com/articles/159601