Kubernetes - Using Helm Charts

Introduction to Helm Charts

Helm charts are a collection of files that describe a related set of Kubernetes resources. This guide provides an understanding of how to use Helm charts in Kubernetes, which is essential for efficiently managing your Kubernetes applications.

What is a Helm Chart?

A Helm chart is a package of pre-configured Kubernetes resources. It includes all the necessary files to deploy and manage a Kubernetes application. Helm charts are reusable and can be versioned, making it easy to manage the lifecycle of your applications.

# 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
                

Creating a Helm Chart

To create a new Helm chart, use the helm create command. This command generates a boilerplate structure for your chart:

# Create a new Helm chart
helm create mychart

# Navigate to the chart directory
cd mychart

# View the generated files
tree .
                

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 ./mychart -f custom-values.yaml
                

Installing and Managing Helm Charts

Once you have customized your Helm chart, you can install and manage it using the following commands:

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

# Update Helm repositories
helm repo update

# Install a chart from a repository
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
                

Chart Dependencies

Helm charts can depend on other charts. You can define these dependencies in the Chart.yaml file. Here is an example of specifying chart dependencies:

# Example of defining chart dependencies in Chart.yaml
dependencies:
  - name: nginx
    version: "1.2.3"
    repository: "https://charts.helm.sh/stable"
                

Best Practices

Follow these best practices when using Helm charts in Kubernetes:

• 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 Charts: Test your Helm charts in a staging environment before deploying 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 overview of using Helm charts in Kubernetes, including creating, customizing, installing, and managing charts. By using Helm charts, 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.