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Helm - Kubernetes Package Manager

Deploying Kubernetes application which involve creating multiple resources – such as pods, services, deployments, and replicasets which requires YAML manifest file. But this can be very complex.

Helm is the package manager for Kubernetes. Like any other package managers(yum, apt), Helm provide a standard way to deploy, configure, upgrade, and run an Kubernetes application in a matter of minutes.

Helm uses a packaging format called charts. A chart is a collection of files that describe a related set of Kubernetes resources.

You can check this sample helm chart which can deploy nginx along with service and configmap.

Installation

brew install kubernetes-helm

Others can follow instructions from here.

How it works

Helm Package Manager has two major components:

Helm Client - command-line client for end users.

  • Local chart development
  • Interacting with the Tiller server
  • Getting release details

Tiller - incluster server that interacts with the Helm client

  • Listening for incoming requests from the Helm client
  • Combining a chart and configuration to build a release
  • Installing charts into Kubernetes, and then tracking the subsequent release
  • Upgrading and uninstalling charts by interacting with Kubernetes

HelmArch

Getting starting with HELM Chart Templating

Before creating Helm Charts, lets go through the Helm Chart directory structure.

mychart/
  Chart.yaml   # contains a description of the chart
  values.yaml  # This file contains the default values for a chart
  charts/      # contain other charts(subcharts)
  templates/   # template of K8s manifest files
  ...

Make sure you have running kubernetes cluster and HELM cli installed.

Initialize helm cli:

helm init --client-only

List Helm default repositories:

helm repo list

Lets follow offcial helm documetaion for creating first chart.

Adding new repositories:

helm repo add zeiss https://zeisshelmrepo.blob.core.windows.net/helm/

helm repo list
helm search zeiss

You can also search for public charts:

$ helm search redis

NAME                            	CHART VERSION	APP VERSION	DESCRIPTION
stable/prometheus-redis-exporter	3.0.0        	1.0.3      	Prometheus exporter for Redis metrics
stable/redis                    	9.0.1        	5.0.5      	Open source, advanced key-value store. It is often referr...
stable/redis-ha                 	3.6.2        	5.0.5      	Highly available Kubernetes implementation of Redis
stable/sensu                    	0.2.3        	0.28       	Sensu monitoring framework backed by the Redis transport

Install kubernetes application using helm:

## Dry run
helm install --namespace $(whoami) zeiss/k8s-handson -n $(whoami) --dry-run --debug

## Install
helm install --namespace $(whoami) zeiss/k8s-handson -n $(whoami)

## To list installed helm releases.
helm ls

## Get manifest created by our helm release
helm get manifest $(whoami)

## Delete helm release
helm delete $(whoami) # This will still keep the history

helm ls -a

## Delete release with history as well
helm delete --purge $(whoami)