How to Create Helm Charts from Scratch

Helm charts package Kubernetes applications for easy deployment and sharing. Learn to create charts with templates, values, and dependencies.

Create Chart Scaffold

# Create new chart
helm create myapp

# Chart structure:
# myapp/
# ├── Chart.yaml          # Chart metadata
# ├── values.yaml         # Default values
# ├── charts/             # Dependencies
# ├── templates/          # Kubernetes manifests
# │   ├── deployment.yaml
# │   ├── service.yaml
# │   ├── ingress.yaml
# │   ├── hpa.yaml
# │   ├── serviceaccount.yaml
# │   ├── _helpers.tpl    # Template helpers
# │   ├── NOTES.txt       # Post-install notes
# │   └── tests/
# └── .helmignore

Chart.yaml

# Chart.yaml
apiVersion: v2
name: myapp
description: A Helm chart for MyApp
type: application
version: 0.1.0        # Chart version
appVersion: "1.0.0"   # Application version

keywords:
  - myapp
  - web

maintainers:
  - name: Platform Team
    email: platform@example.com

dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled
  - name: redis
    version: "17.x.x"
    repository: "https://charts.bitnami.com/bitnami"
    condition: redis.enabled

values.yaml

# values.yaml
replicaCount: 2

image:
  repository: myapp
  pullPolicy: IfNotPresent
  tag: ""  # Defaults to appVersion

imagePullSecrets: []
nameOverride: ""
fullnameOverride: ""

serviceAccount:
  create: true
  annotations: {}
  name: ""

podAnnotations: {}
podSecurityContext:
  runAsNonRoot: true
  runAsUser: 1000

securityContext:
  allowPrivilegeEscalation: false
  readOnlyRootFilesystem: true
  capabilities:
    drop:
      - ALL

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  className: nginx
  annotations: {}
  hosts:
    - host: myapp.local
      paths:
        - path: /
          pathType: Prefix
  tls: []

resources:
  limits:
    cpu: 500m
    memory: 512Mi
  requests:
    cpu: 100m
    memory: 128Mi

autoscaling:
  enabled: false
  minReplicas: 2
  maxReplicas: 10
  targetCPUUtilizationPercentage: 80

nodeSelector: {}
tolerations: []
affinity: {}

# Application config
config:
  logLevel: info
  database:
    host: localhost
    port: 5432

# Dependencies
postgresql:
  enabled: true
  auth:
    database: myapp
redis:
  enabled: false

Template Helpers (_helpers.tpl)

# templates/_helpers.tpl
{{/*
Expand the name of the chart.
*/}}
{{- define "myapp.name" -}}
{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
{{- end }}

{{/*
Create a default fully qualified app name.
*/}}
{{- define "myapp.fullname" -}}
{{- if .Values.fullnameOverride }}
{{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }}
{{- else }}
{{- $name := default .Chart.Name .Values.nameOverride }}
{{- if contains $name .Release.Name }}
{{- .Release.Name | trunc 63 | trimSuffix "-" }}
{{- else }}
{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
{{- end }}
{{- end }}
{{- end }}

{{/*
Common labels
*/}}
{{- define "myapp.labels" -}}
helm.sh/chart: {{ include "myapp.chart" . }}
{{ include "myapp.selectorLabels" . }}
app.kubernetes.io/version: {{ .Values.image.tag | default .Chart.AppVersion | quote }}
app.kubernetes.io/managed-by: {{ .Release.Service }}
{{- end }}

{{/*
Selector labels
*/}}
{{- define "myapp.selectorLabels" -}}
app.kubernetes.io/name: {{ include "myapp.name" . }}
app.kubernetes.io/instance: {{ .Release.Name }}
{{- end }}

{{/*
Chart name and version
*/}}
{{- define "myapp.chart" -}}
{{- printf "%s-%s" .Chart.Name .Chart.Version | replace "+" "_" | trunc 63 | trimSuffix "-" }}
{{- end }}

{{/*
Service account name
*/}}
{{- define "myapp.serviceAccountName" -}}
{{- if .Values.serviceAccount.create }}
{{- default (include "myapp.fullname" .) .Values.serviceAccount.name }}
{{- else }}
{{- default "default" .Values.serviceAccount.name }}
{{- end }}
{{- end }}

Deployment Template

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "myapp.fullname" . }}
  labels:
    {{- include "myapp.labels" . | nindent 4 }}
spec:
  {{- if not .Values.autoscaling.enabled }}
  replicas: {{ .Values.replicaCount }}
  {{- end }}
  selector:
    matchLabels:
      {{- include "myapp.selectorLabels" . | nindent 6 }}
  template:
    metadata:
      annotations:
        checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}
        {{- with .Values.podAnnotations }}
        {{- toYaml . | nindent 8 }}
        {{- end }}
      labels:
        {{- include "myapp.selectorLabels" . | nindent 8 }}
    spec:
      {{- with .Values.imagePullSecrets }}
      imagePullSecrets:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      serviceAccountName: {{ include "myapp.serviceAccountName" . }}
      securityContext:
        {{- toYaml .Values.podSecurityContext | nindent 8 }}
      containers:
        - name: {{ .Chart.Name }}
          securityContext:
            {{- toYaml .Values.securityContext | nindent 12 }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          ports:
            - name: http
              containerPort: 8080
              protocol: TCP
          livenessProbe:
            httpGet:
              path: /health
              port: http
            initialDelaySeconds: 10
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /ready
              port: http
            initialDelaySeconds: 5
            periodSeconds: 5
          resources:
            {{- toYaml .Values.resources | nindent 12 }}
          envFrom:
            - configMapRef:
                name: {{ include "myapp.fullname" . }}
          {{- if .Values.postgresql.enabled }}
          env:
            - name: DATABASE_HOST
              value: {{ .Release.Name }}-postgresql
            - name: DATABASE_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: {{ .Release.Name }}-postgresql
                  key: postgres-password
          {{- end }}
      {{- with .Values.nodeSelector }}
      nodeSelector:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      {{- with .Values.affinity }}
      affinity:
        {{- toYaml . | nindent 8 }}
      {{- end }}
      {{- with .Values.tolerations }}
      tolerations:
        {{- toYaml . | nindent 8 }}
      {{- end }}

ConfigMap Template

# templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ include "myapp.fullname" . }}
  labels:
    {{- include "myapp.labels" . | nindent 4 }}
data:
  LOG_LEVEL: {{ .Values.config.logLevel | quote }}
  DATABASE_PORT: {{ .Values.config.database.port | quote }}
  {{- range $key, $value := .Values.config.extra }}
  {{ $key }}: {{ $value | quote }}
  {{- end }}

Conditional Ingress

# templates/ingress.yaml
{{- if .Values.ingress.enabled -}}
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: {{ include "myapp.fullname" . }}
  labels:
    {{- include "myapp.labels" . | nindent 4 }}
  {{- with .Values.ingress.annotations }}
  annotations:
    {{- toYaml . | nindent 4 }}
  {{- end }}
spec:
  ingressClassName: {{ .Values.ingress.className }}
  {{- if .Values.ingress.tls }}
  tls:
    {{- range .Values.ingress.tls }}
    - hosts:
        {{- range .hosts }}
        - {{ . | quote }}
        {{- end }}
      secretName: {{ .secretName }}
    {{- end }}
  {{- end }}
  rules:
    {{- range .Values.ingress.hosts }}
    - host: {{ .host | quote }}
      http:
        paths:
          {{- range .paths }}
          - path: {{ .path }}
            pathType: {{ .pathType }}
            backend:
              service:
                name: {{ include "myapp.fullname" $ }}
                port:
                  number: {{ $.Values.service.port }}
          {{- end }}
    {{- end }}
{{- end }}

Chart Testing

# Lint chart
helm lint ./myapp

# Template rendering (dry-run)
helm template myrelease ./myapp

# Template with custom values
helm template myrelease ./myapp -f custom-values.yaml

# Install with dry-run
helm install myrelease ./myapp --dry-run --debug

# Run tests
helm test myrelease

Package and Publish

# Update dependencies
helm dependency update ./myapp

# Package chart
helm package ./myapp

# Push to OCI registry
helm push myapp-0.1.0.tgz oci://registry.example.com/charts

# Or push to ChartMuseum
curl --data-binary "@myapp-0.1.0.tgz" https://chartmuseum.example.com/api/charts

Summary

Helm charts package Kubernetes applications with templates and values for customization. Use _helpers.tpl for reusable template functions, conditional blocks for optional resources, and dependencies for external charts. Lint and test charts before publishing to registries.

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