Helm v/s Kustomize

Introduction

• Helm is a powerful tool for managing Kubernetes applications, offering features like templating, dependency management, and version control. It is ideal for teams looking to package and distribute applications efficiently.

Kustomize

• Kustomize is a configuration customization tool for Kubernetes clusters. It allows administrators to make declarative changes using untemplated files, leaving original manifests untouched.
• All customization specifications are contained within a kustomization.yaml file, which superimposes specifications on top of existing manifests to generate custom versions of resources.
• Kustomize also ships with resource generators (secretGenerator and configMapGenerator) that use environment files or key-value pairs to create secrets and ConfigMaps.
• To inject these secrets and ConfigMaps into Kubernetes infrastructure, you define them within the customization file using secretGenerator and configMapGenerator fields, with attributes that specify source files or key-value pairs.

Helm

• Helm is a package manager for Kubernetes that simplifies the deployment and management of applications by using charts, which are pre-configured application templates.
• It allows administrators to define reusable templates and manage application configurations using values files, enabling consistent deployments across environments.
• Helm supports dependency management, making it easier to manage complex applications with multiple components.
• With features like versioning and rollback, Helm ensures better control over application lifecycle management in Kubernetes.

Helm v/s Kustomize

Dimension	Helm	Kustomize
Overall purpose	Package manager for Kubernetes with support for templating, dependency management, and versioning of applications.	Customize existing Kubernetes YAML manifests by overlaying changes also defined in YAML.
Complexity	More complex to work with, since it introduces the need to learn Go templates and the overall structure of charts.	Simpler to work with, since it leverages only native YAML constructs and does not introduce templating languages.
Customization features	Full templating system with conditionals, loops, functions, and variable substitution.	Strategic merge patches, JSON patches, name prefixes/suffixes, common labels, and annotations.
Use-cases	- Packaging and managing applications and their dependencies - Versioning of applications - More advanced customizations via templates and values files.	- Managing environment-specific customizations (e.g., dev, staging, prod) - Applying patches and modifications without duplicating YAML

Example

• Sample Directory Structure:

  • Kustomize

    hello—world/
    |__ base
    |   |__ deployment. yaml
    |   |__ kustomization. yaml
    |__ overlays
    |   |__production/
    |      |__replica—count. yaml
    |      |__kustomization. yaml
    |   |__dev/
    |      |__replica—count. yaml
    |      |__kustomization. yaml
    

  • Helm

    hello-world-chart/
    |__ charts/                   # (Optional) Subcharts if needed
    |__ templates/                # Contains YAML templates for Kubernetes manifests
    |   |__ deployment.yaml       # Equivalent to `base/deployment.yaml`
    |   |__ _helpers.tpl          # Helm template helpers (e.g., naming conventions)
    |   |__ NOTES.txt             # Chart notes
    |__ values.yaml               # Default values (like base configurations)
    |__ values-production.yaml    # Equivalent to overlays/production configs
    |__ values-dev.yaml           # Equivalent to overlays/dev configs
    |__ Chart.yaml                # Helm chart metadata
    |__ README.md