How to Create and Use Helm Charts

The Problem

You need to package, version, and deploy your Kubernetes applications consistently across multiple environments.

The Solution

Use Helm charts to template and package your Kubernetes manifests, making deployments repeatable and configurable.

Installing Helm

# macOS
brew install helm

# Linux
curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash

# Verify installation
helm version

Using Existing Charts

Add a Repository

helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update

Search for Charts

helm search repo nginx
helm search hub wordpress

Install a Chart

helm install my-nginx bitnami/nginx

List Releases

helm list
helm list --all-namespaces

Uninstall a Release

helm uninstall my-nginx

Creating Your Own Chart

Generate Chart Scaffold

helm create myapp

This creates:

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

Chart.yaml

apiVersion: v2
name: myapp
description: A Helm chart for my application
type: application
version: 0.1.0
appVersion: "1.0.0"
keywords:
  - myapp
  - web
maintainers:
  - name: Your Name
    email: your@email.com
dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: https://charts.bitnami.com/bitnami
    condition: postgresql.enabled

values.yaml

replicaCount: 2

image:
  repository: myapp
  pullPolicy: IfNotPresent
  tag: "1.0.0"

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  className: nginx
  hosts:
    - host: myapp.example.com
      paths:
        - path: /
          pathType: Prefix

resources:
  limits:
    cpu: 500m
    memory: 256Mi
  requests:
    cpu: 100m
    memory: 128Mi

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

postgresql:
  enabled: true
  auth:
    username: myapp
    database: myapp

Template Examples

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:
      labels:
        {{- include "myapp.selectorLabels" . | nindent 8 }}
    spec:
      containers:
        - name: {{ .Chart.Name }}
          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
          readinessProbe:
            httpGet:
              path: /ready
              port: http
          resources:
            {{- toYaml .Values.resources | nindent 12 }}
          env:
            {{- if .Values.postgresql.enabled }}
            - name: DATABASE_HOST
              value: {{ include "myapp.fullname" . }}-postgresql
            - name: DATABASE_USER
              value: {{ .Values.postgresql.auth.username }}
            - name: DATABASE_NAME
              value: {{ .Values.postgresql.auth.database }}
            {{- end }}

_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 }}
{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
{{- end }}
{{- end }}

{{/*
Common labels
*/}}
{{- define "myapp.labels" -}}
helm.sh/chart: {{ include "myapp.chart" . }}
{{ include "myapp.selectorLabels" . }}
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 }}

Working with Charts

Lint Your Chart

helm lint myapp/

Dry Run / Template

# See rendered templates
helm template myapp ./myapp

# Dry run against cluster
helm install myapp ./myapp --dry-run --debug

Install Your Chart

helm install myapp ./myapp -f custom-values.yaml

Upgrade a Release

helm upgrade myapp ./myapp --set image.tag=2.0.0

Rollback

helm rollback myapp 1

Package for Distribution

helm package myapp/
# Creates myapp-0.1.0.tgz

Environment-Specific Values

Create separate value files:

# values-dev.yaml
replicaCount: 1
image:
  tag: "dev"

# values-prod.yaml
replicaCount: 3
image:
  tag: "1.0.0"
resources:
  limits:
    memory: 512Mi

Deploy:

helm install myapp ./myapp -f values-prod.yaml

Common Template Functions

# Default value
{{ .Values.foo | default "bar" }}

# Required value
{{ required "A valid .Values.image.tag is required!" .Values.image.tag }}

# Conditional
{{- if .Values.ingress.enabled }}
# ingress manifest
{{- end }}

# Range/Loop
{{- range .Values.ingress.hosts }}
- host: {{ .host | quote }}
{{- end }}

# Quote strings
value: {{ .Values.name | quote }}

# ToYaml
{{- toYaml .Values.resources | nindent 12 }}

Best Practices

1. Use helpers for repeated labels and names
2. Validate inputs with required
3. Set defaults for optional values
4. Quote strings to avoid YAML issues
5. Document values.yaml with comments
6. Version your charts semantically

Key Takeaways

• Helm simplifies Kubernetes deployments
• Charts are reusable, versioned packages
• values.yaml configures templates
• Use helm template to debug
• Create separate values files per environment

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