Helm vs Kustomize: Which to Use

💡 Quick Answer: Compare Helm and Kustomize for Kubernetes configuration management. Covers templating vs overlays, use cases, pros and cons, and when to use both together.

The Problem

This is one of the most searched Kubernetes topics. A comprehensive, well-structured guide helps engineers of all levels quickly find actionable solutions.

The Solution

Detailed implementation with production-ready examples below.

Helm: Template Engine + Package Manager

# Install a chart
helm install my-app bitnami/nginx --set replicaCount=3

# Values file
cat values.yaml
# replicaCount: 3
# image:
#   repository: nginx
#   tag: "1.25"
helm install my-app ./chart -f values.yaml

# Template preview
helm template my-app ./chart -f values.yaml

Kustomize: Overlay-Based Patching

# Base
cat base/deployment.yaml    # Standard deployment
cat base/kustomization.yaml
# resources:
#   - deployment.yaml
#   - service.yaml

# Overlay (per environment)
cat overlays/production/kustomization.yaml
# resources:
#   - ../../base
# patches:
#   - path: replica-patch.yaml
# images:
#   - name: my-app
#     newTag: v2.0

# Apply
kubectl apply -k overlays/production/

Comparison

Use Both Together

# Render Helm chart, then patch with Kustomize
# kustomization.yaml
helmCharts:
  - name: nginx
    repo: https://charts.bitnami.com/bitnami
    version: 15.0.0
    valuesFile: values.yaml
patches:
  - path: add-labels.yaml

graph TD
    A{Choose tool} -->|Third-party apps, registries| B[Helm]
    A -->|Internal apps, GitOps| C[Kustomize]
    A -->|Complex needs| D[Both: Helm + Kustomize overlays]

Frequently Asked Questions

Can I use both?

Yes! Common pattern: use Helm charts for third-party apps (Prometheus, nginx), Kustomize overlays for your own apps. ArgoCD and Flux support both natively.

Common Issues

Check kubectl describe and kubectl get events first — most issues have clear error messages pointing to the root cause.

Best Practices

• Follow least privilege — only grant the access that’s needed
• Test in staging before applying to production
• Monitor and alert on key metrics
• Document your runbooks for the team

Key Takeaways

• Essential knowledge for Kubernetes operations
• Start simple and evolve your approach
• Automation reduces human error
• Share knowledge with your team