Helm vs Kustomize Head-to-Head Comparison

Introduction

Kubernetes has become the go-to container orchestration tool for enterprises across the world. The flexibility of Kubernetes is a result of its ability to automate deployment, scaling, and management of containerized applications. However, with great power comes great complexity.

Deploying applications on Kubernetes requires managing YAML files that embody the application's configuration. These YAML files can easily get out of hand as applications grow in scale and complexity.

To tackle this challenge, Kubernetes provides a set of tools to manage these configurations efficiently. Among these tools are Helm and Kustomize.

Overview of Helm and Kustomize

Kubernetes has become the preferred container orchestration platform for modern containerized applications. Managing Kubernetes manifests can be a daunting task, especially when they are large and complex. Helm and Kustomize are two popular open-source tools that help to simplify Kubernetes deployment.

Explanation of Helm

Helm is a package manager for Kubernetes that helps users to manage, deploy, and share applications on top of a Kubernetes cluster. With Helm, users can define, install, and upgrade complex applications as a single unit.

Features

• Templating − Helm supports templated configuration files that allow users to customize deployment parameters based on their specific requirements.

• Chart Repository − Users can create and share charts via the chart repository feature in Helm.

• Rollback Capabilities − In case of any issues during deployment or upgrades, users can easily roll back to previous versions with the rollback capability feature.

• Release Management − It allows users to manage multiple releases with different versions simultaneously.

Advantages

• Simplified Deployment − Helm simplifies how complex applications are deployed into Kubernetes clusters from yaml files.

• Versioning & Rollbacks − With versioning & rollback capabilities provided by helm you have better control over your deployments

• Reusability − Since you can use templates across multiple deployments you get better code reusability which results in faster deployments

Limitations

• Steep Learning Curve − The learning curve for using helm could be steep for beginners who are new to both kubernetes and helm.

• Compatibility Issues − The charts created by one user may not necessarily work as expected when used by another user due to compatibility issues

Explanation of Kustomize

Kustomize is an open-source tool that enables users to configure Kubernetes applications through patches. With Kustomize, users can customize Kubernetes applications and manage configuration files without changing the original resource definition.

Features

• Patch Management − Kustomize allows users to patch Kubernetes resources using separate configuration files.

• Resource Customization − Users can customize Kubernetes resources using different overlays.

• Merge Configurations − Multiple configurations can be merged into a single configuration file for deployment.

Advantages

• Decentralized Deployment − With kustomize, you have the flexibility to deploy your changes from different source control repos

• Simplifies Configuration Management − By separating application configuration from manifests and infrastructure information kustomize simplifies managing changes in configuration when deploying complex applications

Limitations

• Lack of Control over Dependencies − Kustomize does not have any dependencies management system which can lead to issues when managing multiple configurations.

• Limited Templating Capabilities − Unlike Helm which has an extensive templating engine, Kustomize's templating capabilities are limited leading to less customization options.

Comparison on Key Features

Templating Engine

One of the key features of both Helm and Kustomize is their ability to use templates to generate Kubernetes manifests. Helm uses the Go templating engine, which allows you to use conditional statements, loops, and variables in your templates.

This provides a lot of flexibility when generating manifests, allowing you to customize them for different environments or configurations. However, this can also make Helm's templating engine somewhat complex and difficult to understand.

Kustomize also has a templating system that is much simpler than Helm's. It uses a variant of the Jsonnet language that allows you to define variables and reuse them throughout your manifests.

Kustomize's templates are also easier to read and understand compared to Helm's templates. However, Kustomize's templating engine isn't as powerful as Helm's, which can limit your ability to customize your manifests.

Rollback Capability

Another important feature for any deployment tool is the ability to roll back changes if something goes wrong during an upgrade or update. Both Helm and Kustomize have rollback capabilities built in. Helm allows you to roll back releases using the `helm rollback` command.

This will revert your deployment back to the previous version and update all resources with the saved values from that release. However, it does not provide any way of rolling forward from that point.

Kustomize has a similar rollback capability but with some limitations; it cannot rollback multiple changes at once because it only generates Kubernetes YAML files based on patching previous states. If there are many changes between states then rolling back requires undoing each change manually.

Customization Capabilities

When deploying applications using Kubernetes, you often need a high degree of customization for different environments or configurations such as secrets or environment variables needed only for certain environments such as Production or Development pipeline. Both Helm and Kustomize offer different ways of customizing your deployments. Helm has a robust system for managing values and providing a convenient way of overriding these values with --set flags or using `values.yaml` files.

This enables users to customize the deployment templates to their specific use cases, however, it requires more experience in how Helm works to manage these values without errors. Kustomize uses a similar strategy for managing configuration files using overlays, which enables you to customize Kubernetes manifests by adding or changing fields from existing YAML structures.

Performance Comparison Between Helm vs Kustomize

When it comes to Kubernetes deployment, any tool used for the job must be able to perform well under pressure. This is why performance comparison between Helm and Kustomize is necessary. In terms of performance, Helm and Kustomize both have their strengths and weaknesses.

Deployment Speed Comparison Between Helm vs Kustomize

Helm is a relatively mature tool with a lot of predefined charts that can be used for deployment. Due to this, the time taken to deploy using Helm is faster compared to Kustomize which requires more customizations.

Additionally, deploying multiple applications simultaneously in Helm can also be faster compared to deploying the same applications with Kustomize. Kustomize on the other hand takes longer on its initial deployment especially if there were no templates saved previously or if there are too many manifests in the pipeline.

Resource Usage Comparison Between Helm vs Kustomize

Both tools have different approaches in resource usage. For example, since helm has a large number of predefined charts that can be used for deployments without requiring much effort from developers, it tends to use more resources during runtime compared to kustomize. Kubernetes operators may prefer kustomize as it allows them finer control over how resources are created; this may lead to a situation where cluster resource utilization is optimized (as you're only creating what you need).

Features Comparison in Table

Features	Kustomize	Helm
Native K8s Integration	Yes	No
Overlays	Yes	No
Visibility and Transparency	Strong	Weak
Packaging	No	Yes
Version Control, Rollbacks	No	Yes
Templating	No	Yes

Conclusion

Both Helm and Kustomize are powerful tools for deploying applications on Kubernetes. However, choosing the right tool depends on the specific needs of your project.