Exploring the Differences Between Kustomize and Helm

Exploring the Differences Between Kustomize and Helm

June 21, 2023
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Introduction

If you're trying to decide between Kustomize and Helm to manage your Kubernetes deployments, let me assure you that both tools are excellent options. Allow me to provide some help to help you make the best choice for your particular use case.

But to choose the perfect tool for your mission, you need to learn and understand its capabilities and applications.

This blog post offers guidance on each tool to help you learn about their advantages for every situation, which questions you should ask yourself before choosing Helm or Kustomize, and explains their risk and limitations.

So let's dive in and explore the differences between Kustomize and Helm, and discover which one is the better fit for your use case.

⚠️
Our documentation is a valuable resource, but it can't cover every use case or keep up with the rapid pace of technology. Join the Develeap community to stay informed, share insights, and explore the ever-evolving possibilities.

Pros And Cons

HelmKustomize
Pros
TemplatingSimplicity
PackagingDeclarative Configuration
VersioningKubernetes Native
Large Community
Cons
ComplexityLimited Templating
UpdatesNo Packaging and No Versioning
OverheadCommunity

Benefits Point by Point

What benefits does templating provide for applications?

  • Consistency: Templating ensures that configuration files are consistent across different environments, which reduces the chance of errors or unexpected behavior.
  • Flexibility: With templates, you can define variables that can be customized for different environments, making it easy to adapt your application to different use cases or environments.
  • Reusability: Templates can be reused across different applications or environments, which can save time and effort when deploying new applications or updating existing ones.
  • Version control: Templating enables you to version control your configuration files, making it easy to track changes and roll back to previous versions if necessary.
  • Scalability: Templating simplifies the process of deploying and managing applications at scale, making it easier to manage large, complex systems.
Overall, templating is a powerful tool for simplifying the process of deploying and managing applications, reducing the risk of errors, and improving overall consistency and scalability.

What benefits does Packaging provide for applications?

  1. Portability: Packaging an application allows it to be easily moved between different environments and platforms.
  1. Consistency: Packaging ensures that the application is deployed with all of its dependencies and configurations, reducing the risk of errors or unexpected behavior.
  1. Scalability: Packaging simplifies the process of deploying and managing applications at scale, making it easier to manage large, complex systems.

What benefits does Versioning provide for applications?

  1. Control: Versioning allows you to track changes to your application over time, making it easier to roll back to a previous version if necessary.
  1. Collaboration: Versioning enables multiple developers to work on the same application simultaneously without conflicts or errors.
  1. Stability: Versioning promotes stability by ensuring that changes to the application are tracked and tested before being deployed.

What benefits does Large Community provide for applications?

  1. Support: A large community provides access to support and expertise, making it easier to troubleshoot issues and optimize performance.
  1. Innovation: A large community encourages innovation and development, resulting in new features and capabilities that can benefit your application.
  1. Resources: A large community provides access to a wide range of resources, including documentation, tutorials, and tools, making it easier to develop and deploy your application.

What benefits does Simplicity provide for applications?

  1. Reduced Complexity: Simplifying the deployment process reduces complexity, making it easier to manage and maintain the application.
  1. Faster Deployment: A simpler deployment process leads to faster deployments, which can improve time-to-market and overall productivity.
  1. Reduced Errors: A simpler deployment process reduces the risk of errors or issues that can impact the application's performance.

What benefits does Declarative Configuration provide for applications?

  1. Consistency: Declarative configuration ensures that the desired state of the application is clearly defined, making it easier to maintain consistency across different environments.
  1. Predictability: Declarative configuration provides a clear understanding of how the application should behave, making it easier to predict and troubleshoot issues.
  1. Scalability: Declarative configuration simplifies the process of scaling the application, making it easier to manage and maintain as it grows.

Cons Point by Point

Helm Cons

Helm can be complex to set up and use, especially if you're not familiar with YAML templates and Kubernetes.
ℹ️
Helm introduces an additional layer of abstraction between your application and Kubernetes, which may introduce additional overhead and complexity.

Kustomize Cons:

Kustomize provides limited templating capabilities, which may make it more challenging to customize your application's configuration across different environments.
Kustomize does not provide packaging capabilities like Helm, making it more challenging to share and distribute your application across different teams and environments.
⚠️
Kustomize has a smaller community compared to Helm, which means that you may have to rely more on official documentation and examples.

Let’s See Some Technical and Practical differences

Table comparing various features of Kustomize and Helm:

FeaturesKustomizeHelm
Installation processStandalone utility, typically installed separatelyPackage manager, requires Helm CLI installation
Configuration optionsYAML-based, directory structure, overlaysYAML-based, charts, values files, release-specific settings
TemplatingLimited templating capabilitiesAdvanced templating using Go templates
VersioningSupports version control systems (e.g., Git)Supports versioning through Helm charts and releases
Support for Kubernetes resourcesSupports native Kubernetes resourcesSupports native Kubernetes resources
Packaging and distributionN/ACharts allow packaging and distribution of applications
Dependency managementN/ASupports managing dependencies between components
Ecosystem compatibilityNative integration with Kubernetes ecosystemWidely used within the Kubernetes ecosystem
Learning curveRelatively easy to learn and get started withRequires familiarity with Helm CLI and templating
Community and supportActive community support, official Kubernetes projectActive community support, extensive chart repository
ℹ️
Note: This table is not exhaustive and provides a high-level comparison. Both Kustomize and Helm have additional features beyond those listed. Evaluate your specific requirements and preferences when choosing between the two tools.

Understand the difference between the two directories

Helm Directory Example

myapp/
├── charts/
│   ├── myapp/
│   │   ├── Chart.yaml
│   │   ├── values.yaml
│   │   ├── templates/
│   │   │   ├── deployment.yaml
│   │   │   ├── service.yaml
│   │   │   ├── configmap.yaml
│   │   │   ├── secrets.yaml
│   │   │   ├── ingress.yaml
│   │   │   └── ...
│   │   └── ...
│   ├── mysql/
│   ├── redis/
│   └── ...
├── values/
│   ├── prod/
│   │   ├── values.yaml
│   │   ├── values-secrets.yaml
│   │   └── ...
│   ├── stage/
│   ├── test/
│   └── ...
├── pkg/
│   └── ...
├── scripts/
│   └── ...
├── Dockerfile
├── Makefile
└── cmd/
    └── ...

Helm Values File

# Define global variables that apply to all components
global:
  namespace: default
  imagePullSecrets: []
  annotations: {}
  labels: {}

# Configure the replica count for the deployment
replicaCount: 1

# Define environment variables for the container
env:
  - name: DB_HOST
    value: localhost
  - name: DB_PORT
    value: "5432"
  - name: DB_NAME
    value: myappdb
  - name: DB_USERNAME
    value: myappuser
  - name: DB_PASSWORD
    valueFrom:
      secretKeyRef:
        name: db-credentials
        key: password

# Define the container image and tag to use
image:
  repository: myorg/myapp
  tag: 1.0.0

# Define resources requests and limits for the container
resources:
  requests:
    cpu: 100m
    memory: 128Mi
  limits:
    cpu: 200m
    memory: 256Mi

# Define the service type to use (ClusterIP, NodePort, LoadBalancer, ExternalName)
service:
  type: ClusterIP
  port: 8080

# Define an ingress for the service
ingress:
  enabled: false
  annotations: {}
  hosts:
    - host: myapp.example.com
      paths:
        - path: /
  tls: []

# Define additional config files to include
config:
  files:
    - name: config.yml
      content: |-
        key1: value1
        key2: value2

# Define additional secrets to include
secrets:
  - name: db-credentials
    data:
      username: bXlhcHB1c2VyCg==
      password: cGFzc3dvcmQK

Kustomize Directory Example

myapp/
├── base/
│   ├── kustomization.yaml
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── configmap.yaml
│   ├── secrets.yaml
│   ├── ingress.yaml
│   └── ...
├── overlays/
│   ├── prod/
│   │   ├── kustomization.yaml
│   │   ├── deployment.yaml
│   │   ├── service.yaml
│   │   ├── configmap.yaml
│   │   ├── secrets.yaml
│   │   ├── ingress.yaml
│   │   └── ...
│   ├── stage/
│   │   ├── kustomization.yaml
│   │   ├── deployment.yaml
│   │   ├── service.yaml
│   │   ├── configmap.yaml
│   │   ├── secrets.yaml
│   │   ├── ingress.yaml
│   │   ├── patch.yaml
│   │   ├── generator.yaml
│   │   └── ...
│   ├── test/
│   └── ...
├── cmd/
│   └── ...
├── pkg/
│   └── ...
├── scripts/
│   └── ...
├── Dockerfile
├── Makefile
└── .gitignore

Kustomize File Example

# kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../base

patches:
  - patch-deployment.yaml

namespace: production
# config-generator.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: ConfigMapGenerator

metadata:
  name: myapp-config

literals:
- FOO=bar
- BAZ=qux
# patch-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 3
  template:
    spec:
      containers:
      - name: myapp
        image: myregistry/myapp:latest
        ports:
        - containerPort: 8080
        env:
        - name: ENVIRONMENT
          value: production
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 100
            podAffinityTerm:
              labelSelector:
                matchExpressions:
                - key: app
                  operator: In
                  values:
                  - myapp
              topologyKey: kubernetes.io/hostname

Let’s Understand the potential Risk and Limitation

Let's assess the risks and determine their priority:

Working With Helm

Dependency risks: Helm charts can have complex dependencies that may not be properly managed, resulting in deployment errors or conflicts. In addition, Helm charts can potentially rely on outdated or vulnerable dependencies, posing a risk to the overall stability and security of the deployed application.
⚠️
Security risks: Helm packages can contain custom code, which can pose a security risk if the code is not thoroughly vetted. In addition, Helm can potentially be used to deploy insecure configurations, such as using default passwords or using unsecured communication channels.
ℹ️
Operational risks: Helm can be complex to use and configure, which can lead to operational risks such as misconfigurations, errors, or even downtime if the application is not properly deployed or managed. In addition, Helm can potentially create additional complexity in a deployment environment, which can further increase the risk of errors or downtime.

Working With Kustomize

Complexity: Kustomize can become quite complex and difficult to understand as the number of components and overlays increases. This may make it challenging for new users to understand how to use Kustomize and manage the components.
Risk of human error: As with any configuration management tool, there is a risk of human error. Users need to be careful when making changes to their Kustomize configuration, as mistakes can have significant consequences for their other infrastructure.
Lack of documentation: Although Kustomize has good documentation, it can sometimes be challenging to find the specific information you need. This can make it challenging for users to get started with Kustomize or solve specific problems.
⚠️
Security risks: As with any tool that is used to manage infrastructure, there are potential security risks associated with Kustomize. Users need to ensure that they have secured their infrastructure and have appropriate access controls in place to protect their configurations.
⚠️
Lack of flexibility: Kustomize is designed to work with Kubernetes manifests, and it may not be as flexible as other tools that can work with different kinds of configurations or environments.
ℹ️
Compatibility issues: Kustomize has different versions, and sometimes a newer version may not be compatible with an older version. Therefore, it is essential to ensure that all users have the same version of Kustomize.

Let's analyze the strengths and limitations of Kustomize and Helm in real-world scenarios:

Helm

Advanced templating capabilities: Helm's powerful templating engine using Go templates is highly regarded, enabling dynamic configuration generation, conditional logic, and reusable templates. This flexibility is valuable for complex deployments.
Packaging and distribution: Helm's ability to package applications as charts and share them within the Kubernetes community is a significant advantage. It simplifies the distribution and deployment of complex applications.
Dependency management: Helm's built-in support for managing dependencies between different components simplifies deployment and ensures consistency in complex systems.
Tightly coupled with Kubernetes: While Helm is powerful within the Kubernetes ecosystem, it may not be the best fit for managing configurations outside of Kubernetes or for simpler deployments that don't require advanced templating and packaging features.
Learning curve and complexity: Helm is considered to have a steeper learning curve compared to Kustomize. The Helm CLI, chart structure, and templating language (Go templates) may require time and effort to master.

Kustomize

Simplicity and ease of use: Kustomize is often praised for its simplicity, making it a good fit for smaller projects or straightforward configuration management tasks.
Native integration with Kubernetes: Kustomize's tight integration with Kubernetes is considered a significant advantage, as it aligns well with the Kubernetes ecosystem and other Kubernetes tools.
Version control-friendly: The file-based approach of Kustomize makes it easy to track changes and collaborate using version control systems like Git.
Limited templating capabilities: Kustomize's limited templating features can be a drawback for more complex deployments that require dynamic configuration generation or advanced templating logic.
Lack of native dependency management: Kustomize lacks built-in support for managing dependencies between different components, which can be a limitation when dealing with complex applications with interdependent resources.

🌳 Decision Tree


Conclusion

Summary

ℹ️
When deciding between Kustomize and Helm in real-world scenarios, there are several factors to consider. Kustomize is simple and integrates directly with Kubernetes, making it a good choice for small projects or straightforward configuration management tasks. Meanwhile, Helm is better suited for complex deployments and sharing applications as charts within the Kubernetes community because of its advanced templating, packaging, distribution, and dependency management features. However, for projects outside the Kubernetes ecosystem or simpler deployments, Helm's learning curve and tight coupling with Kubernetes may be a consideration.
⚠️
It's important to consider your specific project requirements, team expertise, and ecosystem compatibility when choosing between Kustomize and Helm. Real-world feedback from developers and DevOps engineers within your organization or community can provide valuable insights tailored to your specific use cases.

My Opinion

⚖️
To summarize, Kustomize is the recommended choice for simple projects with limited dependencies, and the only challenge is managing several environments that you manage. However, for most other scenarios, Helm is the better choice due to its advanced templating, packaging, distribution, and dependency management features.