Why Helm simplifies deployments in Kubernetes - Why It Works

Introduction

Deploying applications on Kubernetes can be complex because you must manage many configuration files. Helm helps by packaging these files into a single chart, making deployment easier and repeatable.

When you want to deploy an application with multiple Kubernetes resources like deployments, services, and config maps together.

When you need to update your application frequently and want to manage versions easily.

When you want to share your application setup with others in a simple package.

When you want to customize deployments for different environments without rewriting configuration files.

When you want to roll back to a previous version of your application quickly if something goes wrong.

Config File - Chart.yaml

Chart.yaml

apiVersion: v2
name: my-app
description: A simple Helm chart for deploying my-app
version: 0.1.0
appVersion: "1.0"

apiVersion: Specifies the Helm chart version format.

name: The name of your application chart.

description: A short explanation of what this chart does.

version: The version of the chart itself, used for managing updates.

appVersion: The version of the application being deployed.

Commands

This command creates a new Helm chart named 'my-app' with a basic folder structure and example files to start your deployment.

Terminal

helm create my-app

Expected Output

Creating my-app



Created directory my-app

Created Chart.yaml

Created values.yaml

Created templates/deployment.yaml

Created templates/service.yaml

Created templates/_helpers.tpl

Created .helmignore

This command installs the 'my-app' chart into your Kubernetes cluster, deploying all resources defined in the chart.

Terminal

helm install my-app ./my-app

Expected Output

NAME: my-app

LAST DEPLOYED: Fri Apr 26 12:00:00 2024

NAMESPACE: default

STATUS: deployed

REVISION: 1

NOTES:

1. Get the application URL by running these commands:

  export POD_NAME=$(kubectl get pods --namespace default -l "app.kubernetes.io/name=my-app,app.kubernetes.io/instance=my-app" -o jsonpath='{.items[0].metadata.name}')

  echo "Visit http://127.0.0.1:8080 to use your application"

  kubectl port-forward $POD_NAME 8080:80

This command lists all Helm releases installed in your Kubernetes cluster, showing their status and version.

Terminal

helm list

Expected Output

NAME    NAMESPACE   REVISION    UPDATED                     STATUS      CHART         APP VERSION

my-app  default     1           2024-04-26 12:00:00.000000  deployed    my-app-0.1.0  1.0

This command upgrades the existing 'my-app' release with any changes made in the chart files, applying updates without downtime.

Terminal

helm upgrade my-app ./my-app

Expected Output

Release "my-app" has been upgraded. Happy Helming!

NAME: my-app

LAST DEPLOYED: Fri Apr 26 12:05:00 2024

NAMESPACE: default

STATUS: deployed

REVISION: 2

NOTES:

1. Get the application URL by running these commands:

  export POD_NAME=$(kubectl get pods --namespace default -l "app.kubernetes.io/name=my-app,app.kubernetes.io/instance=my-app" -o jsonpath='{.items[0].metadata.name}')

  echo "Visit http://127.0.0.1:8080 to use your application"

  kubectl port-forward $POD_NAME 8080:80

This command rolls back the 'my-app' release to revision 1, undoing the last upgrade if it caused problems.

Terminal

helm rollback my-app 1

Expected Output

Rollback was a success! Happy Helming!

NAME: my-app

LAST DEPLOYED: Fri Apr 26 12:10:00 2024

NAMESPACE: default

STATUS: deployed

REVISION: 3

NOTES:

1. Get the application URL by running these commands:

  export POD_NAME=$(kubectl get pods --namespace default -l "app.kubernetes.io/name=my-app,app.kubernetes.io/instance=my-app" -o jsonpath='{.items[0].metadata.name}')

  echo "Visit http://127.0.0.1:8080 to use your application"

  kubectl port-forward $POD_NAME 8080:80

Key Concept

If you remember nothing else from this pattern, remember: Helm packages all Kubernetes resources into one chart to make deploying, updating, and rolling back apps simple and repeatable.

Common Mistakes

Trying to deploy Kubernetes resources manually without using Helm charts.

This causes repetitive work and makes updates or rollbacks difficult and error-prone.

Use Helm charts to bundle resources and manage deployments with simple commands.

Not updating the chart version in Chart.yaml before upgrading the release.

Helm may not recognize changes properly, causing upgrade failures or confusion.

Always increment the chart version in Chart.yaml when making changes before running helm upgrade.

Ignoring the output notes after helm install or upgrade commands.

You might miss important instructions like how to access your application or check its status.

Read the notes carefully to understand how to interact with your deployed app.

Summary

Use 'helm create' to generate a new chart with all necessary files for deployment.

Deploy your app with 'helm install' to apply all Kubernetes resources at once.

Manage updates easily with 'helm upgrade' and undo changes with 'helm rollback'.