Helm Charts

Package and deploy Kubernetes applications using Helm, the package manager for Kubernetes.

When to Use This Skill

Use this skill when:

• Creating reusable Kubernetes application packages
• Deploying applications with configurable values
• Managing Helm releases and upgrades
• Using third-party Helm charts
• Implementing chart versioning and repositories

Prerequisites

• Helm 3.x installed
• kubectl configured with cluster access
• Basic Kubernetes knowledge

Chart Structure

mychart/
├── Chart.yaml          # Chart metadata
├── values.yaml         # Default configuration values
├── charts/             # Chart dependencies
├── templates/          # Kubernetes manifest templates
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── configmap.yaml
│   ├── secret.yaml
│   ├── _helpers.tpl    # Template helpers
│   ├── NOTES.txt       # Post-install notes
│   └── tests/
│       └── test-connection.yaml
└── .helmignore         # Files to ignore

Chart.yaml

apiVersion: v2
name: myapp
description: A Helm chart for MyApp
type: application
version: 1.0.0
appVersion: "2.0.0"
keywords:
  - myapp
  - web
maintainers:
  - name: DevOps Team
    email: devops@example.com
dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled

values.yaml

replicaCount: 2

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

service:
  type: ClusterIP
  port: 80

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

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

postgresql:
  enabled: true
  auth:
    database: myapp

Templates

Deployment Template

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "myapp.fullname" . }}
  labels:
    {{- include "myapp.labels" . | nindent 4 }}
spec:
  replicas: {{ .Values.replicaCount }}
  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
          {{- with .Values.resources }}
          resources:
            {{- toYaml . | nindent 12 }}
          {{- end }}
          env:
            - name: DATABASE_URL
              valueFrom:
                secretKeyRef:
                  name: {{ include "myapp.fullname" . }}-secrets
                  key: database-url

Helper Functions

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

{{/*
Common labels
*/}}
{{- define "myapp.labels" -}}
helm.sh/chart: {{ .Chart.Name }}-{{ .Chart.Version }}
{{ include "myapp.selectorLabels" . }}
app.kubernetes.io/version: {{ .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 }}

Conditional Resources

# 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 }}

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