How to Use Helm Template for Kubernetes Manifests

Use helm template to render Kubernetes manifests from a Helm chart locally without installing them on a cluster. Run helm template [release-name] [chart-path] to output the generated YAML files to your terminal or save them for inspection.

Syntax

The basic syntax of helm template is:

• helm template [RELEASE_NAME] [CHART]: Renders templates with the given release name and chart path.
• --values, -f: Specify custom values files to override defaults.
• --output-dir: Save rendered manifests to a directory instead of printing.
• --namespace: Set the Kubernetes namespace in the rendered manifests.

bash

helm template [RELEASE_NAME] [CHART] [flags]

Example

This example shows how to render manifests from the official nginx Helm chart without installing it. It outputs the Kubernetes YAML to the terminal for review.

bash

helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update
helm template my-nginx bitnami/nginx --namespace webserver

Output

---
# Source: nginx/templates/service.yaml
apiVersion: v1
kind: Service
metadata:
  name: my-nginx
  namespace: webserver
spec:
  type: ClusterIP
  ports:
    - port: 80
      targetPort: http
  selector:
    app.kubernetes.io/name: nginx
    app.kubernetes.io/instance: my-nginx
---
# Source: nginx/templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
  namespace: webserver
spec:
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: nginx
      app.kubernetes.io/instance: my-nginx
  template:
    metadata:
      labels:
        app.kubernetes.io/name: nginx
        app.kubernetes.io/instance: my-nginx
    spec:
      containers:
        - name: nginx
          image: docker.io/bitnami/nginx:latest
          ports:
            - name: http
              containerPort: 80
          resources: {}

Common Pitfalls

• Not specifying a release name: Helm requires a release name to render templates correctly; omitting it can cause errors.
• Using helm install instead of helm template: helm install deploys resources to the cluster, while helm template only renders manifests locally.
• Ignoring values overrides: Forgetting to pass custom values files with -f can lead to unexpected default configurations.
• Output confusion: Large output can be overwhelming; use --output-dir to save files for easier inspection.

bash

## Wrong: Missing release name
helm template bitnami/nginx

## Right: Include release name
helm template my-nginx bitnami/nginx

Quick Reference

Here is a quick summary of useful helm template flags:

Flag	Description
--values, -f	Specify values file to override defaults
--namespace	Set namespace in rendered manifests
--output-dir	Save rendered manifests to directory
--set	Set individual values on the command line
--show-only