To understand what Helm is, let’s first look at Kubernetes. Kubernetes is an open-source platform designed to automate the deployment, scaling, and management of containerized applications. While Kubernetes is a robust tool, managing applications on it can be a complex task, especially when dealing with multiple microservices or environments. This is where Helm comes in.
Kubernetes Helm, known as the Kubernetes package manager, is a tool that simplifies the deployment and management of applications on Kubernetes. It uses a packaging format called charts, which are collections of files that describe a related set of Kubernetes resources. A single chart can be used to deploy something simple, like a memcached pod, or something complex, like a full web app stack with HTTP servers, databases, caches, and so on.
In essence, Helm is to Kubernetes what apt, yum, or brew are to operating systems like Ubuntu, CentOS, or MacOS, respectively. It provides tech professionals with an easy way to package, share, and deploy applications and manage the lifecycle of those applications.
The History and Evolution of Helm
Helm was born out of the need to simplify the management of applications on Kubernetes. It was created in 2015 as a hackathon project by Deis, a company that was later acquired by Microsoft. The initial version of Helm was simple, focusing mainly on the deployment of pre-packaged applications to Kubernetes.
In 2016, Helm joined the Kubernetes organization as part of the Kubernetes project. This marked the beginning of Helm’s evolution into a more robust tool. Helm 2, released later that same year, introduced Tiller, a server-side component that managed the release lifecycle. This version made Helm more powerful but also introduced a new set of complexities and security concerns.
Recognizing the need for a more secure and simpler tool, the Helm community embarked on developing Helm 3, which was released in 2019. Helm 3 eliminated the need for Tiller, making Helm more secure and easier to use. It also introduced several new features, including improved release management, chart repositories, and library charts, making Helm a must-have tool for any tech professional working with Kubernetes.
Main Components of Kubernetes Helm
Helm Charts are at the heart of Helm’s functionality. They are the packaging format used by Helm, containing a description of the application and how it should be deployed. A Helm chart is a collection of files that describe a related set of Kubernetes resources.
A single chart might define everything necessary to run a single service, or it might aggregate several services into a complex application. For instance, a chart could contain all the Kubernetes resources necessary to run an HTTP server, a database, and a cache, all configured to work together.
Helm CLI (Command Line Interface)
The Helm CLI is the primary way users interact with Helm. It is a command-line tool that allows you to manage your Helm applications. With the Helm CLI, you can create new charts, package your charts into chart archives, interact with chart repositories, and deploy your charts into Kubernetes clusters.
The Helm Chart Repository
The Helm Chart Repository is a place where packaged charts can be shared and stored. It is essentially a HTTP server that houses an index.yaml file and some packaged charts. When you’re ready to share your application, you can package it into a chart and push it to a Helm Chart Repository. From there, other users can fetch and deploy your application into their own Kubernetes clusters.
The official Helm Chart Repository is the Helm Hub, but you can also use other hosted chart repositories, or even host your own.
Benefits of Using Helm in Kubernetes
Simplified Application Deployment
One of the most significant benefits of using Helm in Kubernetes is the simplified application deployment it provides. With traditional Kubernetes deployment, you would need to describe your application’s structure and behaviors in extensive detail using Kubernetes’ primitives. However, Helm streamlines this process, creating a higher-level, more manageable abstraction. This allows you to define, install, and upgrade applications on Kubernetes without getting entangled in the complexity of individual Kubernetes components.
Helm packages these Kubernetes components into logical units, allowing you to manage your applications more efficiently. It follows a chart format, where each chart represents an application. These charts contain all the resources and configurations your application needs to run on Kubernetes, effectively simplifying the deployment process.
Another great advantage of Helm is its ability to manage dependencies. With Kubernetes, managing the dependencies between different services and applications can be a challenging task. Helm, however, makes this easy.
Helm charts can define dependencies and even package dependencies along with the main application, thus ensuring that all the components required to run the application are deployed together. The Helm CLI (Command Line Interface) also allows you to update or rollback dependencies as a group, thus maintaining consistency and avoiding conflicts between service versions.
Versioning and Release Management
Helm also shines in its versioning and release management capabilities. Helm charts are versioned, which means you can upgrade or rollback your applications to any version easily. This is a powerful feature, especially in production environments where stability and reliability are paramount.
Additionally, Helm also tracks your releases. A release is an instance of a chart running in a Kubernetes cluster. Helm allows you to rollback releases, making it an invaluable tool for maintaining the stability of your applications. It tracks the history of releases and provides the capability to rollback to a previous release in case of an error or failure.
Reusability Through Pre-configured Helm Charts
Last but not least, Helm provides reusability through pre-configured Helm charts. Helm charts are templates that can be reused across different environments and teams. This saves a lot of time and resources as you don’t have to reinvent the wheel every time you deploy an application.
In fact, Helm provides a public repository of pre-configured Helm charts, known as the Helm Hub. These charts are contributed by the community and are ready to be used out-of-the-box. This not only facilitates reusability but also fosters a community-driven approach to application deployment in Kubernetes.
Best Practices for Using Helm in Kubernetes
While Helm can do many things, it’s important to remember that simplicity is key. One of the main reasons to use Helm is to abstract away complexity and make application deployment easier. Therefore, it’s crucial to keep your charts as simple as possible.
This means avoiding overly complex configurations and keeping your charts readable and understandable. Remember, others might need to read and understand your charts, so clarity is essential. The simpler your charts are, the more maintainable and reusable they will be.
Leverage Built-In Objects
Helm has a variety of built-in objects that you can use in your charts. These objects can be used to control the flow of template rendering, perform logical operations, and access properties of the chart or release.
By leveraging these built-in objects, you can create dynamic charts that adapt to different environments and configurations. This makes your charts more flexible and reusable, increasing the overall efficiency of your application deployment process.
Keep Charts DRY (Don’t Repeat Yourself)
As with any coding practice, it’s important to keep your Helm charts DRY (Don’t Repeat Yourself). Duplicating code in your Helm charts not only makes them harder to maintain but also increases the likelihood of errors.
Helm provides several features to keep your charts DRY. For example, you can use the include directive to include snippets of code in multiple places. You can also define helper templates that can be reused throughout your chart.
Secure Your Helm Usage
Security should always be a top priority when using any technology, and Helm is no exception. Helm provides several features to help you secure your Helm usage.
For example, you can use Helm’s role-based access control (RBAC) to control who can install, upgrade, or delete releases. You can also use Helm’s secret management to securely store sensitive information, such as passwords and API keys.
Additionally, it’s important to only use trusted charts from trusted sources. While the Helm Hub provides a wealth of community-contributed charts, not all of them may be secure or reliable. Always verify the source and integrity of the charts you use.
Maintain a Well-Organized Chart Repository
Lastly, it’s important to maintain a well-organized chart repository. A chart repository is a place where packaged charts can be stored and shared.
Organizing your chart repository well will make it easier for you and others to find and use your charts. This includes giving your charts meaningful names, documenting your charts properly, and versioning your charts.
In conclusion, Kubernetes Helm is a powerful tool that can greatly simplify application deployment and management in Kubernetes. However, like any tool, it’s important to use it wisely and follow best practices to reap its full benefits. By understanding the benefits of Helm and following the best practices outlined in this guide, you can become a proficient user of Helm and take your Kubernetes skills to the next level.
Author Bio: Gilad David Maayan Gilad David Maayan is a technology writer who has worked with over 150 technology companies including SAP, Imperva, Samsung NEXT, NetApp and Check Point, producing technical and thought leadership content that elucidates technical solutions for developers and IT leadership. Today he heads Agile SEO, the leading marketing agency in the technology industry. LinkedIn: https://www.linkedin.com/in/giladdavidmaayan/