Create Custom Helm Charts

Intermediate20 minTrending

Scaffold, structure, and build custom Helm charts for your applications with proper templates, helpers, and values files.

Prerequisites

-Helm 3 installed
-Basic understanding of Kubernetes manifests
-Familiarity with Go templates

Steps

Scaffold a new chart

Generate the default Helm chart directory structure.

$ helm create myapp

The scaffold includes a Deployment, Service, ServiceAccount, Ingress, and HPA template ready to customize.

Explore the chart structure

Understand the key files and directories in the generated chart.

$ find myapp -type f | sort

Edit the values file

Customize the default values that will be used across your templates.

$ cat myapp/values.yaml

Keep values.yaml well-documented with comments explaining each parameter and its default.

Add a custom template

Create a ConfigMap template using Helm template syntax.

$ cat > myapp/templates/configmap.yaml << 'EOF' apiVersion: v1 kind: ConfigMap metadata: name: {{ include "myapp.fullname" . }}-config labels: {{- include "myapp.labels" . | nindent 4 }} data: APP_ENV: {{ .Values.config.environment | quote }} LOG_LEVEL: {{ .Values.config.logLevel | quote }} EOF

Render templates locally

Preview the generated Kubernetes manifests without deploying.

$ helm template my-release myapp --set config.environment=production --set config.logLevel=warn

Package the chart

Create a versioned .tgz archive of the chart for distribution.

$ helm package myapp --version 1.0.0 --app-version 1.0.0

Full Script

full-script.sh

#!/bin/bash
# Helm Chart Creation Workflow
set -euo pipefail

CHART_NAME=${1:?"Usage: $0 <chart-name>"}

echo "=== Scaffolding Chart ==="
helm create "$CHART_NAME"

echo ""
echo "=== Chart Structure ==="
find "$CHART_NAME" -type f | sort

echo ""
echo "=== Adding ConfigMap Template ==="
cat > "$CHART_NAME/templates/configmap.yaml" << 'TMPL'
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ include "CHART.fullname" . }}-config
  labels:
    {{- include "CHART.labels" . | nindent 4 }}
data:
  APP_ENV: {{ .Values.config.environment | default "development" | quote }}
  LOG_LEVEL: {{ .Values.config.logLevel | default "info" | quote }}
TMPL

# Replace CHART placeholder with actual chart name
sed -i "s/CHART/$CHART_NAME/g" "$CHART_NAME/templates/configmap.yaml"

echo ""
echo "=== Rendering Templates ==="
helm template test-release "$CHART_NAME"

echo ""
echo "=== Linting Chart ==="
helm lint "$CHART_NAME"

echo ""
echo "=== Packaging Chart ==="
helm package "$CHART_NAME"

echo "Done! Chart packaged as $CHART_NAME-0.1.0.tgz"

FAQ

Discussion

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#!/bin/bash # Helm Chart Creation Workflow set -euo pipefail CHART_NAME=${1:?"Usage: $0 <chart-name>"} echo "=== Scaffolding Chart ===" helm create "$CHART_NAME" echo "" echo "=== Chart Structure ===" find "$CHART_NAME" -type f | sort echo "" echo "=== Adding ConfigMap Template ===" cat > "$CHART_NAME/templates/configmap.yaml" << 'TMPL' apiVersion: v1 kind: ConfigMap metadata: name: {{ include "CHART.fullname" . }}-config labels: {{- include "CHART.labels" . | nindent 4 }} data: APP_ENV: {{ .Values.config.environment | default "development" | quote }} LOG_LEVEL: {{ .Values.config.logLevel | default "info" | quote }} TMPL # Replace CHART placeholder with actual chart name sed -i "s/CHART/$CHART_NAME/g" "$CHART_NAME/templates/configmap.yaml" echo "" echo "=== Rendering Templates ===" helm template test-release "$CHART_NAME" echo "" echo "=== Linting Chart ===" helm lint "$CHART_NAME" echo "" echo "=== Packaging Chart ===" helm package "$CHART_NAME" echo "Done! Chart packaged as $CHART_NAME-0.1.0.tgz"