Helm vs Kustomize
Compare Helm and Kustomize for Kubernetes configuration management. Understand differences, use cases, and when to choose each tool for your deployments.
Helm
Kustomize
Comparison
Overview: Helm vs Kustomize
Both Helm and Kustomize are popular tools for managing Kubernetes configurations, but they approach the problem differently:
- Helm is a package manager that uses templating to generate Kubernetes manifests. It's ideal for packaging and sharing applications.
- Kustomize is a configuration management tool that uses overlays to modify base configurations. It's ideal for managing environment-specific variations.
Key Insight: Helm and Kustomize are not mutually exclusive. Many organizations use both—Helm for packaging and sharing, Kustomize for environment-specific overlays.
Feature Comparison
Helm
Paradigm: Package Management & Templating
Approach: Go templates with values
Reusability: High (charts are sharable)
Learning Curve: Steep (needs Go template knowledge)
Versioning: Built-in (chart versioning)
Rollbacks: Yes (helm rollback)
OCI Registry: Yes (Helm v3)
GitOps: Yes (ArgoCD, Flux)
Kustomize
Paradigm: Configuration Management
Approach: Overlays and patches
Reusability: Medium (base + overlays)
Learning Curve: Low (YAML-based)
Versioning: Git-based
Rollbacks: Git revert
OCI Registry: No
GitOps: Yes (ArgoCD, Flux)
Helm: Package Manager
Helm uses Go templating to generate Kubernetes manifests. It packages configurations into charts that can be versioned, shared, and reused.
# Helm Chart Structure
my-app/
├── Chart.yaml # Chart metadata
├── values.yaml # Default values
├── templates/
│ ├── deployment.yaml # Deployment template
│ ├── service.yaml # Service template
│ └── _helpers.tpl # Helper functions
# Deployment Template (deployment.yaml)
apiVersion: apps/v1
kind: Deployment
metadata:
name: {{ include "my-app.fullname" . }}
labels:
app: {{ include "my-app.name" . }}
spec:
replicas: {{ .Values.replicaCount }}
selector:
matchLabels:
app: {{ include "my-app.name" . }}
template:
metadata:
labels:
app: {{ include "my-app.name" . }}
spec:
containers:
- name: {{ .Chart.Name }}
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
ports:
- containerPort: {{ .Values.service.port }}
# values.yaml
replicaCount: 3
image:
repository: nginx
tag: latest
service:
type: ClusterIP
port: 80
# Install with overrides
helm install my-release ./my-app --set replicaCount=5 --set image.tag=1.25
Helm Strengths:
- Packaging: Charts are shareable and versioned
- Dependency Management: Manage subcharts and dependencies
- Release Management: Track release history, rollbacks
- Community: Large ecosystem of public charts
- OCI Support: Store charts in OCI registries
Kustomize: Configuration Management
Kustomize uses a base + overlay pattern to manage configurations. It applies patches and transformations to base YAML without templating.
# Kustomize Directory Structure
my-app/
├── base/
│ ├── kustomization.yaml
│ ├── deployment.yaml
│ └── service.yaml
└── overlays/
├── dev/
│ └── kustomization.yaml
├── staging/
│ └── kustomization.yaml
└── prod/
└── kustomization.yaml
# base/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- deployment.yaml
- service.yaml
# base/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-app
spec:
replicas: 3
selector:
matchLabels:
app: my-app
template:
metadata:
labels:
app: my-app
spec:
containers:
- name: my-app
image: nginx:latest
ports:
- containerPort: 80
# overlays/dev/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- ../../base
patchesStrategicMerge:
- patch.yaml
images:
- name: nginx
newTag: dev
# overlays/dev/patch.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-app
spec:
replicas: 1
# Apply with overlays
kubectl apply -k overlays/dev/
Kustomize Strengths:
- No Templating: Uses plain YAML, no learning curve for templating
- GitOps Friendly: Base + overlays pattern fits GitOps workflows
- Built-in: Integrated with kubectl (
kubectl apply -k) - Overlay Pattern: Clean environment separation
- Patches: Strategic merge and JSON patches
Detailed Comparison Table
┌─────────────────────────────────┬──────────────────────────┬──────────────────────────┐
│ Feature │ Helm │ Kustomize │
├─────────────────────────────────┼──────────────────────────┼──────────────────────────┤
│ Paradigm │ Package Manager │ Configuration Management │
│ Approach │ Go Templating │ Overlays & Patches │
│ Learning Curve │ Steep │ Low │
│ Reusability │ High (Charts) │ Medium (Base + Overlays) │
│ Versioning │ Built-in │ Git-based │
│ Rollbacks │ Helm rollback │ Git revert │
│ Dependency Management │ Yes (subcharts) │ No │
│ OCI Registry │ Yes (Helm v3) │ No │
│ Environment Overlays │ Values files │ Overlay directories │
│ Templating │ Go templates │ None (plain YAML) │
│ Community │ Large │ Growing │
│ Complexity │ Higher │ Lower │
│ GitOps Integration │ Excellent │ Excellent │
When to Use Helm vs Kustomize
Use Helm When...
✓ You need to package and share applications
✓ You need dependency management
✓ You want to version and release charts
✓ You need complex templating
✓ You use public chart repositories
✓ You need OCI registry support
✓ You want release rollback capabilities
Example: Deploying a complex application with dependencies
Use Kustomize When...
✓ You want a simple, templating-free solution
✓ You manage environment-specific configurations
✓ You want to use plain YAML
✓ You need a GitOps-friendly approach
✓ You want to use built-in kubectl integration
✓ You prefer overlays over templating
✓ You have simple configuration needs
Example: Managing dev/staging/prod overlays for a simple app
Frequently Asked Questions
Can I use Helm and Kustomize together?
Yes! Many organizations use both together. For example, use Helm to package and distribute charts, then use Kustomize to apply environment-specific overlays. ArgoCD and Flux both support this workflow.
Which is better for GitOps?
Both are excellent for GitOps. Kustomize is simpler and more Git-native (base + overlays). Helm provides more packaging capabilities. ArgoCD and Flux support both natively.
What is the learning curve for each?
Kustomize has a lower learning curve—it's just YAML overlays. Helm requires learning Go templating, which is more complex but more powerful for complex scenarios.
Which is more popular?
Helm is more popular overall (larger community, more charts). Kustomize is growing in popularity, especially for GitOps workflows. Both are CNCF projects.
Can I use Helm charts without Helm?
Yes, you can render Helm templates with
helm template and use the output with kubectl. This is common in CI/CD pipelines or when you want to avoid Helm's release management. Is Kustomize included in kubectl?
Yes! Kustomize is built into kubectl. Use
kubectl apply -k <directory> to apply Kustomize overlays directly. What are the alternatives to Helm and Kustomize?
Alternatives include plain YAML manifests, jsonnet, and operators. Helm and Kustomize are the most popular and widely adopted tools.
Can I use both in the same project?
Yes! Many teams use Helm for packaging and Kustomize for environment overlays. For example, use Helm to create charts and Kustomize to customize them for different environments.
Related Topics
Choose Helm for packaging and sharing applications. Choose Kustomize for simple configuration management. Use both together for the best of both worlds.