Kubernetes - Introduction to Helm

Understanding Helm

Helm is a package manager for Kubernetes that helps you define, install, and upgrade even the most complex Kubernetes applications. This guide provides an understanding of Helm and its use cases.

What is Helm?

Helm is a package manager for Kubernetes that enables you to deploy, manage, and share Kubernetes applications. Helm uses charts, which are packages of pre-configured Kubernetes resources, to deploy and manage applications. Helm charts are reusable and can be versioned, making it easy to manage application deployments and rollbacks.

# Example of a simple Helm chart directory structure
mychart/
  Chart.yaml    # A YAML file containing information about the chart
  values.yaml   # The default configuration values for this chart
  charts/       # A directory containing any charts upon which this chart depends
  templates/    # A directory of templates that, when combined with values, will generate valid Kubernetes manifest files
                

Installing Helm

To get started with Helm, you need to install it on your local machine. Here is an example of installing Helm on Linux/macOS using a script:

# Download and install Helm
curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash

# Verify the installation
helm version
                

For other operating systems and installation methods, refer to the official Helm installation guide.

Using Helm

Once Helm is installed, you can start using it to manage your Kubernetes applications. Here are some basic Helm commands:

# Add a Helm repository
helm repo add stable https://charts.helm.sh/stable

# Update Helm repositories
helm repo update

# Search for available charts
helm search repo

# Install a chart
helm install my-release stable/mychart

# List installed releases
helm list

# Upgrade a release
helm upgrade my-release stable/mychart

# Rollback a release
helm rollback my-release 1

# Uninstall a release
helm uninstall my-release
                

Helm Charts

Helm charts are packages of pre-configured Kubernetes resources. A chart can contain all the resource definitions necessary to run an application, tool, or service inside a Kubernetes cluster. Here is an example of a basic Helm chart structure:

# Example of a Helm chart directory structure
mychart/
  Chart.yaml    # A YAML file containing information about the chart
  values.yaml   # The default configuration values for this chart
  charts/       # A directory containing any charts upon which this chart depends
  templates/    # A directory of templates that, when combined with values, will generate valid Kubernetes manifest files
                

Customizing Helm Charts

You can customize Helm charts by modifying the values.yaml file or providing your own values file during installation. This allows you to override default settings and configure the application according to your needs. Here is an example:

# Example of customizing a Helm chart using a values file
# Create a custom values file (custom-values.yaml)
replicaCount: 2
image:
  repository: nginx
  tag: stable
  pullPolicy: IfNotPresent

# Install the chart with custom values
helm install my-release stable/mychart -f custom-values.yaml
                

Best Practices

Follow these best practices when using Helm:

• Use Versioned Charts: Always use versioned charts to ensure consistency and reproducibility.
• Store Custom Values: Store custom values files in version control to keep track of configuration changes.
• Test Upgrades: Test chart upgrades in a staging environment before applying them to production.
• Automate Deployments: Use CI/CD pipelines to automate Helm chart deployments and updates.
• Leverage Helm Repositories: Use Helm repositories to share and distribute charts within your organization or with the community.

Conclusion

This guide provided an introduction to Helm, including its installation, usage, and best practices. By using Helm, you can simplify the deployment and management of Kubernetes applications, making it easier to handle complex application lifecycle tasks such as upgrades, rollbacks, and configuration management.