A Beginner’s Guide to Understanding Helm in Kubernetes

Kubernetes has been one of the most popular and almost the de facto standard for container orchestration. Kubernetes is a portable, extensible, open-source platform for managing containerized workloads & services that facilitates both declarative configuration and automation, according to Kubernetes.io. Google open-sourced the Kubernetes project in 2014. Today, Kubernetes combines over 15 years of Google’s experience running production workloads at scale with best-of-breed ideas & practices from the community, adds Kubernetes.io.

One important tool in Kubernetes is Helm. Helm is a package manager for Kubernetes manifests (like deployments, ConfigMaps, Services, etc.) that enables users to manage & install applications, making it easier to manage & deploy the applications to the Kubernetes clusters. Helm helps users package their applications into a single ‘chart’ file which would contain all the necessary resources & dependencies for the application required for running the application in a Kubernetes environment. A chart is a template used for creating & deploying applications on Kubernetes using Helm. Since, with this everything can be managed in a single ‘chart’ file instead of managing everything individually, so deploying & managing the application becomes so much easier. As a package manager, Helm offers users the functionality for templating as well as lifecycle management.

In a way, it would not be an understatement to say that Helm is an essential tool for anybody looking to deploy applications to Kubernetes.

 

What is Helm Architecture?

There are two key components of a client/server architecture in Helm:

1. The Helm Client:

   This is the user interface component of Helm helping create new charts, manage repositories, and release packages. It also helps developers test upgrades before releasing them into production.

2. The Helm Library:

   This is a set of client libraries that are used for interacting with the Kubernetes API server. These libraries are used to install, upgrade, or even rollback the Helm charts. This would be installed on every node present in the cluster and a user would require this component for installing any chart.

Now, we mentioned something called Helm Charts here, so let us take a look at what are Helm charts.

What are Helm Charts?

Charts are the packaging formats used by Helm. Charts would contain the specifications which would define the Kubernetes objects which comprise the application, such as the YAML files, the templates, etc. which would be converted into Kubernetes manifest files. These charts can be reused in different environments and will not be limited to one environment. Due to their reusable nature, when using charts, complexity gets significantly reduced while the risk of having duplicates is also minimized.

When it comes to Helm charts, there are three major concepts one needs to know:

1. The Helm Chart:

   It is a pre-configured template used for provisioning Kubernetes resources

2. The Release:

   It is the Helm chart that has been deployed

3. The Repository:

   It is the location – public or private, that is used for storing charts

When a developer works with Helm, they would look through the repositories for the charts. The charts are then installed onto the Kubernetes clusters. This leads to the release. This is how the flow works across these three concepts in Helm Charts.

What is the Helm Chart Structure?

Every file and directory in a Helm Chart will be serving a specific function, for instance:

Charts Directory

The charts directory would include all the charts that the main chart would depend on. Every main chart could depend on multiple different charts and all of these would exist in the chart directory.

Templates

The templates folder would contain the manifests which would be deployed along with the chart. So, suppose there is an application that has to be deployed which would require a service, a config map, and secrets. So, the template directory for this application would contain a deployment.yaml, a service.yaml a config.yaml, and a secrets.yaml. The values for each of these files would come from the values.yaml file. This values file would contain the default configurations values for the charts.

Here, charts.yaml would be the file which contains the required meta-information like the version, the name, the search keywords, etc.

What are the benefits of using Helm?

Helm is extremely popular among developers and DevOps professionals as Helm works incredibly well when it comes to automating complex Kubernetes deployments. Helm helps free up their bandwidth so they can focus on more value-added tasks. Additionally, Helm is super user-friendly so one doesn’t need any special skills or expertise to be able to use it. Helm’s user interface is also very intuitive so cluster deployments can be managed with ease.

Here are some of the benefits of using Helm:

1. Security:

   Helm ranks high on security solutions so packages can be installed securely on the clusters the user trusts

2. Flexibility:

   Helm also ranks high on flexibility and customizability which gives users the freedom to install different packages on the Kubernetes cluster

3. Large Ecosystem of Packages:

   Helm offers a very large ecosystem of packages thus enabling the user to find any package they are looking for easily

4. Active Support Community:

   Being open-sourced, Helm has an active community of users & developers which offers all the support anybody needs no matter the challenge they encounter

5. Simplified Deployment:

   One can provision the Kubernetes resources in just a few clicks or with just a command on a command-line interface using Helm charts. Using Helm, even complex deployments can be executed by including charts as dependencies in other charts

6. Easier Versioning:

   Helm offers automatic versioning and keeps an updated database of all the released versions. So, if someday, something goes wrong with the new release, one can easily roll back to the previous version

7. Seamless Integration with CI/CD:

   Helm offers integration hooks that users can configure to accomplish different tasks at different times like before installation or after installation. The hooks can also be configured to monitor the health and run checks on the Helm deployments to keep an eye if the deployments have been successful or not.

8. Enhanced Productivity:

   Using Helm ensures there is no need to re-write the manifests every time. One can easily generate a new chart using any one of the previously used, already existing templates, and voila! When done smartly, an entire new Kubernetes application can be generated in a specific service account with just one line of code.

9. Scalability:

   With Helm, manifests need not be re-written, charts and templates can be easily re-used, making it super easy to scale up or down as needed as the same tasks can be performed quicker and more efficiently.

10. Smoother Kubernetes Learning Curve:

    Kubernetes can turn out to be a complex tool but Helm makes things easier and more approachable. The ability to install the chart with just one command, a highly user-friendly interface, a vast repository, the ability to reuse manifests, creating private repositories as required, etc. Helm has a declarative approach which makes Kubernetes so much more accessible and easier.

Thus, we see how useful and important a tool Helm can be for Kubernetes users or users who are planning to move to Kubernetes, especially the ones still on the fence.

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• Basic command knowledge of Linux
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• Basic knowledge of YAML programming language (beneficial, not mandatory)