Introduction

Helm is a package manager for Kubernetes that makes it easy to deploy, manage, and upgrade applications on a Kubernetes cluster. With Helm, you can define, install, and upgrade complex Kubernetes applications using simple templates called Helm charts. This beginner’s guide will walk you through the basics of getting started with Helm charts, including what Helm is, why you should use it, and how to create and deploy your first Helm chart.

What is Helm?

Helm is a package manager for Kubernetes that simplifies the process of deploying and managing applications on a Kubernetes cluster. Helm uses charts to define the structure of an application and its dependencies, making it easy to package and distribute Kubernetes applications. Helm is an open-source project developed by the Kubernetes community and is widely used in production environments.

Why Use Helm?

Helm is a powerful tool for managing Kubernetes applications, and there are several reasons why you should consider using it:

1. Simplifies Deployment: Helm simplifies the deployment of complex Kubernetes applications by defining their structure in a Helm chart. This makes it easier to deploy and manage Kubernetes applications, especially those with many dependencies.
2. Standardizes Application Packaging: Helm charts provide a standard way of packaging and distributing Kubernetes applications, making it easy to share and collaborate with others.
3. Simplifies Upgrades and Rollbacks: Helm makes it easy to upgrade and rollback Kubernetes applications by keeping track of the changes made to the application and its dependencies. This makes it easy to roll back to a previous version of the application if necessary.
4. Supports Customization: Helm charts can be customized to meet the specific needs of your application, including configuration options, resource limits, and more.
5. Widely Used: Helm is widely used in production environments, and there are many community-supported charts available for popular applications and services.

Getting Started with Helm

To get started with Helm, you will need to install the Helm client on your local machine. The Helm client is a command-line tool that you can use to create, manage, and deploy Helm charts. You will also need access to a Kubernetes cluster to deploy your Helm charts.

Installing the Helm Client

The Helm client can be installed on macOS, Linux, and Windows. To install the Helm client on your local machine, follow these steps:

1. Download the appropriate binary for your operating system from the Helm GitHub repository: https://github.com/helm/helm/releases
2. Extract the binary to a directory in your $PATH. For example, on macOS, you can use the following command:shellCopy code$ tar -zxvf helm-v3.8.0-darwin-amd64.tar.gz $ sudo mv darwin-amd64/helm /usr/local/bin/
3. Verify that the Helm client is installed by running the following command:
   $ helm version version.BuildInfo{Version:"v3.8.0", GitCommit:"2b9034bb09ad48206805a8b1e41bc4c2048401db", GitTreeState:"clean", GoVersion:"go1.17.2"}

Setting up a Kubernetes Cluster

To deploy Helm charts, you will need access to a Kubernetes cluster. If you don’t already have a cluster, you can set up a local cluster using tools like Minikube or Kind. Alternatively, you can use a cloud provider like AWS, GCP, or Azure to provision a cluster.

Creating Your First Helm Chart

Now that you have installed the Helm client and have access to a Kubernetes cluster, you can create your first Helm chart. A Helm chart is a collection of files that define the structure and configuration of a Kubernetes application. Helm charts can include templates, values files, and other resources that are used to deploy

he application to a Kubernetes cluster.

To create a new Helm chart, you can use the Helm command-line interface (CLI) to generate a new chart template:

$ helm create mychart

This command will create a new directory called mychart with a set of default files and directories for your new chart.

The chart directory structure will look like this:

mychart/
  Chart.yaml
  values.yaml
  charts/
  templates/
  README.md

Let’s take a closer look at each of these files and directories:

• Chart.yaml: This file contains the metadata for the Helm chart, including the chart name, version, and description.
• values.yaml: This file contains the default values for the chart’s configuration settings.
• charts/: This directory is used to store any dependencies that your chart may have.
• templates/: This directory contains the template files that define the structure of your Kubernetes resources, such as deployments, services, and configmaps.
• README.md: This file contains a description of the chart and any instructions for using it.

Defining the Chart’s Resources

To define the structure of your Kubernetes resources, you can create a set of template files in the templates/ directory. Helm uses the Go templating language to generate YAML files from your templates, which are then applied to your Kubernetes cluster.

For example, you can create a deployment template file in templates/ called deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-web
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ .Release.Name }}-web
  template:
    metadata:
      labels:
        app: {{ .Release.Name }}-web
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          ports:
            - containerPort: {{ .Values.containerPort }}
          env:
            - name: ENVIRONMENT
              value: {{ .Values.environment }}

This deployment template will create a Kubernetes deployment with a specified number of replicas, image, port, and environment variables.

The {{ .Release.Name }} and {{ .Chart.Name }} variables are used to generate unique names for your resources based on the name of the chart and the release name. The {{ .Values }} variable is used to reference the values defined in the values.yaml file.

Customizing the Chart’s Configuration

To customize the configuration of your Helm chart, you can edit the values in the values.yaml file. The values.yaml file contains a set of default values that can be overridden when you install the chart.

For example, you can set the replicaCount and containerPort values in values.yaml:

replicaCount: 2

image:
  repository: nginx
  tag: 1.21.3

containerPort: 80

environment: "production"

When you install the chart, you can override these values by passing a values file using the --values flag:

$ helm install mychart ./mychart --values myvalues.yaml

In the myvalues.yaml file, you can specify the values to override:

replicaCount: 3

environment: "staging"

Deploying the Chart

To deploy your Helm chart, you can use the helm install command:

$ helm install mychart ./mychart

This command will create a new release of your chart,

With a unique release name and install it on your Kubernetes cluster.

You can then check the status of your release using the helm status command:

$ helm status my-release

This will display information about the resources created by your chart, such as the deployment, service, and configmap.

Updating the Chart

To update your Helm chart, you can make changes to the template files or values in your chart directory, and then use the helm upgrade command to apply the changes to your Kubernetes cluster:

$ helm upgrade my-release ./mychart

This will upgrade the existing release of your chart with the new changes.

Uninstalling the Chart

To uninstall your Helm chart, you can use the helm uninstall command:

$ helm uninstall my-release

This will delete all the resources created by your chart and remove the release from your Kubernetes cluster.

Conclusion

Helm is a powerful tool for managing complex applications on Kubernetes, and Helm charts are a great way to package and deploy your applications. In this guide, we’ve covered the basics of creating a new Helm chart, defining the structure of your Kubernetes resources using template files, and customizing the chart’s configuration using values files.

We’ve also covered how to deploy, update, and uninstall your Helm chart using the Helm CLI. With this knowledge, you should be able to get started with Helm charts and take advantage of their many benefits for managing your Kubernetes applications.