Kubernetes has revolutionised how we deploy, manage, and scale containerised applications. However, managing Kubernetes manifests can become challenging as applications become more complex. This is where Helm, the Kubernetes package manager, comes to the rescue. In this article, we will explore the ins and outs of Helm, its key concepts, and how it simplifies Kubernetes application deployment.
What is Helm?
Helm is often referred to as the “package manager for Kubernetes”. It provides a higher-level abstraction for deploying applications on Kubernetes by defining, installing, and upgrading even the most complex ones. Helm packages are charts, which are a collection of pre-configured Kubernetes resources.
A Helm chart is a package of pre-configured Kubernetes resources that can be deployed as a unit. Charts can include Kubernetes manifest files, templates, and default configuration values. Helm charts make it easy to share and reproduce Kubernetes applications.
Helm uses Go templating to allow dynamic generation of Kubernetes manifest files. Templates enable parameterisation, making it possible to reuse charts with different configurations. This is particularly useful when deploying the same application with variations in environments or settings.
Values are parameters that can be injected into Helm charts during deployment. They provide a way to customise the behaviour of the charts without modifying the chart itself. Values are often defined in a separate YAML file, making managing different configurations for different environments easy.
Helm charts can be hosted in repositories, allowing easy sharing and distribution. The Helm community maintains the official Helm Hub, a centralised repository for discovering and distributing charts. Additionally, organisations can set up private repositories to manage and share their internal charts.
Helm in Action:
To start with Helm, you must install the Helm client on your local machine and the Helm server component, Tiller, in your Kubernetes cluster. However, note that Tiller has been deprecated in Helm 3, and Helm now directly interacts with the Kubernetes API server.
2. Chart Creation:
Creating a Helm chart involves structuring your application’s Kubernetes manifests, defining templates, and specifying default values. Helm provides a “helm create” command to generate a basic chart scaffold, which can then be customised based on your application’s needs.
3. Chart Deployment:
Deploying a Helm chart is a simple command away. Helm provides the “helm install” command to deploy a graph, and you can customise the deployment by specifying values, overriding defaults, or even using different configuration files.
4. Chart Upgrades:
As applications evolve, so do their Kubernetes manifests. Helm makes it easy to upgrade deployed charts with the “helm upgrade” command. This allows seamless updates without manual intervention, simplifying the management of evolving applications.
Versioning: Maintain version numbers for your Helm charts to track changes and updates.
Documentation: Provide comprehensive documentation for your charts, describing configuration options and usage guidelines.
Security: Regularly update Helm and ensure the safety of your Helm charts, especially if using external repositories.
Kubernetes Helm simplifies the deployment and management of applications on Kubernetes, providing a powerful and flexible tool for developers and operators. By leveraging Helm charts, you can streamline your deployment process, enhance collaboration, and ensure consistency across different environments. As Kubernetes continues to evolve, Helm remains a valuable asset in the ever-expanding toolbox of container orchestration.