What is Helm charts - K8s

Helm charts are a package management tool for Kubernetes, designed to simplify the deployment, configuration, and management of applications in Kubernetes clusters. They encapsulate Kubernetes resources (like pods, services, config maps, etc.) into reusable, configurable packages called charts, making it easier to deploy complex applications with minimal manual intervention.

How Helm Charts Work with Kubernetes:

1. Helm Chart Structure:

   • A Helm chart is a collection of YAML templates and files that define a Kubernetes application.
   • Each chart consists of a set of Kubernetes manifests (e.g., deployment.yaml, service.yaml) that define the resources to be deployed.

2. Templating:

   • Helm uses templating to inject dynamic values into these manifests, allowing for flexible and repeatable deployments.
   • Values can be customized using a values.yaml file, which holds default configurations that can be overridden at deployment time.

3. Repositories:

   • Helm charts are stored in repositories (similar to package repositories in other package managers).
   • Public repositories like the official Helm Hub or Artifact Hub host thousands of pre-configured charts for common applications (e.g., NGINX, MySQL, Prometheus, etc.).
   • You can also create private repositories for custom applications.

4. Installing Applications with Helm:

   • Using Helm, you can deploy an application with a single command that references a chart, pulling the chart from a repository and deploying it into your Kubernetes cluster.
   • Example:

     
     helm repo add stable https://charts.helm.sh/stable
     helm install my-release stable/nginx
     

   • This command pulls the NGINX Helm chart, installs it into the Kubernetes cluster, and creates resources like deployments, services, etc.

5. Versioning and Rollbacks:

   • Helm keeps track of chart releases and their versions.
   • You can upgrade, roll back, or uninstall chart releases easily, making it ideal for maintaining application lifecycles.
     • Upgrade: helm upgrade <release-name> <chart-name>
     • Rollback: helm rollback <release-name> <revision-number>

6. Helm Values:

   • values.yaml allows you to define custom configurations. When deploying a Helm chart, you can override these values to change settings like replica counts, image versions, or environment variables.

     
     helm install my-release stable/nginx --set replicaCount=3
     

7. Chart Dependencies:

   • Helm charts can have dependencies on other charts. This enables complex applications to be built using smaller, reusable charts.
   • Dependencies are listed in the Chart.yaml file, and Helm ensures all dependencies are installed alongside the main chart.

Typical Use Cases for Helm Charts in Kubernetes:

• Application Deployment: Helm charts make it easy to deploy applications (databases, web servers, monitoring tools) with a single command.
• Managing Configurations: By using Helm’s templating system, you can manage environment-specific configurations without hardcoding values into Kubernetes manifests.
• Complex Workloads: Helm is ideal for deploying applications with many interconnected resources (e.g., microservices), where you need to manage dependencies and complex configurations.
• Version Control: Helm allows you to version control your application deployments and quickly roll back if something goes wrong.

In summary, Helm charts bring simplicity, modularity, and flexibility to Kubernetes application deployments, offering a powerful way to manage complex workloads and configurations in an efficient, reusable manner.