What is Helm and what does it solve?
Helm is a package manager for Kubernetes, which is an open-source platform for automating the deployment, scaling, and management of containerized applications. Helm helps in managing Kubernetes applications and addresses several important problems:
Complexity of deployment: Kubernetes deployments can be complicated with numerous YAML files for services, pods, volumes, and other resources. Helm packages all of these into a single entity known as a chart. Thus, Helm makes deployments easier and more convenient by simplifying the management of Kubernetes applications. The crucial difference with deploying directly the original YAML manifests is that these files in a Helm chart are organized and managed as a cohesive unit.
Reusability: Helm charts are easy to create, version, share, and publish, so they can be used across different environments. This makes the deployment process repeatable and standardized, thereby reducing potential human errors during the deployment phase.
Manage application dependencies: Helm charts include all the resource definitions necessary to run an application, service, or a complete Kubernetes environment stack in a Kubernetes cluster. It manages and tracks dependencies of packages, which can be defined in a Helm chart to ensure that the correct versions of required dependent charts are installed along with the package.
Release management: Helm not only helps in the initial deployment of applications, but also provides the versioning of the application releases, making it easier to rollback to previous versions if anything goes wrong.
Configurable deployments: Helm charts allow you to parameterize resource specifications, thereby enabling the same chart to be used in different environments (like staging, test, production) with different configurations. This flexibility helps teams to use the same chart in various situations, including the ability to share them within the community.
Community and collaboration: Helm has a strong and active community that shares a vast number of ready-to-use charts for many popular software applications. This open-source aspect facilitates collaboration and speeds up the development process.
Helm helps to manage Kubernetes applications by simplifying deployment, standardizing release process, and managing dependencies.
Use cases
Here are some example use cases that illustrate how Helm is often used:
Application Deployment: Suppose you have a multi-tier web application that consists of a web server, a caching service, and a database server. Deploying and managing such applications can be complex with Kubernetes alone. With Helm, you can create a chart (or use an existing chart if available) that encompasses all of these components, making the deployment process easier and consistent across different environments.
CI/CD Pipelines: Helm can be used in Continuous Integration/Continuous Delivery (CI/CD) pipelines. For example, after an application passes all tests, a Helm chart can be used to deploy the application to a staging environment and then to production. This makes the deployment process repeatable and reduces the chances of errors during the deployment phase.
Microservices Architecture: If you’re using a microservices architecture, managing the deployment of all the services and their interdependencies can be a challenge. Helm makes it easier by allowing you to package each service as a chart, which can then be managed and deployed individually or collectively as needed.
Software Development Lifecycle: Helm can be used to provide consistency across the entire software development lifecycle. Developers can use Helm charts to deploy their application components in their local development environment, ensuring they have the same setup as in production. This reduces the “it works on my machine” problem.
Managed Kubernetes Service Providers: Many managed Kubernetes service providers, such as Google Kubernetes Engine (GKE), Amazon Elastic Kubernetes Service (EKS), and Azure Kubernetes Service (AKS), integrate with Helm. They offer Helm charts for their services, allowing developers to quickly and easily deploy and manage these services in a Kubernetes cluster.
Community Software Deployment: Helm can be used to easily deploy software applications that have been packaged by the community into Helm charts. For example, you can use Helm to deploy applications like WordPress, Jenkins, or MySQL onto your Kubernetes cluster by simply referencing the respective Helm chart.
How does a Helm chart look like?
Here’s a brief overview of a Helm chart’s structure:
mychart/
Chart.yaml # A YAML file containing information about the chart
values.yaml # The default configuration values for this chart
templates/ # A directory of templates that, when combined with values, will generate valid Kubernetes manifest files
deployment.yaml # A template for creating a Kubernetes deployment
service.yaml # A template for creating a Kubernetes service
charts/ # A directory containing any charts upon which this chart depends.
