Helm Charts für Kubernetes

Helm ist der Package Manager für Kubernetes. Lernen Sie Charts zu erstellen, zu konfigurieren und in Produktionsumgebungen einzusetzen.

Was ist Helm?

┌─────────────────────────────────────────────────────────────┐
│                         HELM                                │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│   OHNE HELM:                                                │
│   ┌─────────────────────────────────────────────┐          │
│   │ deployment.yaml                              │          │
│   │ service.yaml                                 │          │
│   │ configmap.yaml          → kubectl apply -f  │          │
│   │ secret.yaml                                  │          │
│   │ ingress.yaml                                 │          │
│   └─────────────────────────────────────────────┘          │
│   × Keine Versionierung                                    │
│   × Keine Parameter                                        │
│   × Schwer zu verwalten                                    │
│                                                             │
│   MIT HELM:                                                │
│   ┌─────────────────────────────────────────────┐          │
│   │ myapp-chart/                                 │          │
│   │   Chart.yaml                                 │          │
│   │   values.yaml           → helm install myapp│          │
│   │   templates/                                 │          │
│   └─────────────────────────────────────────────┘          │
│   ✓ Versioniert                                            │
│   ✓ Parametrisiert                                         │
│   ✓ Wiederverwendbar                                       │
│                                                             │
└─────────────────────────────────────────────────────────────┘

Helm Installation

# macOS
brew install helm

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

# Windows (Chocolatey)
choco install kubernetes-helm

# Version prüfen
helm version

Chart Struktur

myapp/
├── Chart.yaml          # Chart Metadaten
├── values.yaml         # Default Konfiguration
├── charts/             # Abhängigkeiten
├── templates/          # Kubernetes Manifests (Templates)
│   ├── _helpers.tpl    # Template Helpers
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── configmap.yaml
│   ├── ingress.yaml
│   ├── hpa.yaml
│   └── NOTES.txt       # Post-Install Hinweise
└── .helmignore         # Dateien zum Ignorieren

Chart.yaml

# Chart.yaml

apiVersion: v2
name: myapp
description: A Helm chart for MyApp
type: application
version: 1.0.0           # Chart Version
appVersion: "2.3.1"      # App Version

maintainers:
  - name: DevOps Team
    email: devops@example.com

dependencies:
  - name: postgresql
    version: "12.1.0"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled

  - name: redis
    version: "17.0.0"
    repository: "https://charts.bitnami.com/bitnami"
    condition: redis.enabled

values.yaml

# values.yaml - Default Konfiguration

replicaCount: 2

image:
  repository: myapp/backend
  tag: "latest"
  pullPolicy: IfNotPresent

service:
  type: ClusterIP
  port: 80
  targetPort: 8080

ingress:
  enabled: true
  className: nginx
  hosts:
    - host: app.example.com
      paths:
        - path: /
          pathType: Prefix
  tls:
    - secretName: app-tls
      hosts:
        - app.example.com

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

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

env:
  LOG_LEVEL: info
  DATABASE_HOST: postgresql

secrets:
  databasePassword: ""  # Überschreiben bei Installation

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

redis:
  enabled: false

Templates

# 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:
      labels:
        {{- include "myapp.selectorLabels" . | nindent 8 }}
      annotations:
        checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          ports:
            - name: http
              containerPort: {{ .Values.service.targetPort }}
              protocol: TCP
          env:
            {{- range $key, $value := .Values.env }}
            - name: {{ $key }}
              value: {{ $value | quote }}
            {{- end }}
            - name: DATABASE_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: {{ include "myapp.fullname" . }}
                  key: database-password
          livenessProbe:
            httpGet:
              path: /health
              port: http
            initialDelaySeconds: 15
          readinessProbe:
            httpGet:
              path: /ready
              port: http
            initialDelaySeconds: 5
          resources:
            {{- toYaml .Values.resources | nindent 12 }}

# 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: {{ .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 }}

Helm Befehle

# Repository hinzufügen
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update

# Chart suchen
helm search repo nginx
helm search hub wordpress

# Chart installieren
helm install myapp ./myapp                          # Lokaler Chart
helm install myapp bitnami/nginx                    # Aus Repo
helm install myapp ./myapp -f production.yaml       # Mit Values-Datei
helm install myapp ./myapp --set replicaCount=5     # Mit Override

# Namespace angeben
helm install myapp ./myapp -n production --create-namespace

# Dry-Run (nur anzeigen, nicht anwenden)
helm install myapp ./myapp --dry-run --debug

# Template rendern (ohne Installation)
helm template myapp ./myapp

# Upgrade
helm upgrade myapp ./myapp
helm upgrade myapp ./myapp --set image.tag=v2.0.0
helm upgrade --install myapp ./myapp   # Install oder Upgrade

# Rollback
helm rollback myapp 1                   # Zur Revision 1

# Liste aller Releases
helm list
helm list -A                            # Alle Namespaces

# Release Status
helm status myapp

# History
helm history myapp

# Deinstallieren
helm uninstall myapp

Values überschreiben

# values-production.yaml

replicaCount: 5

image:
  tag: "v2.3.1"

resources:
  limits:
    cpu: 1000m
    memory: 512Mi
  requests:
    cpu: 500m
    memory: 256Mi

autoscaling:
  enabled: true
  minReplicas: 5
  maxReplicas: 20

ingress:
  hosts:
    - host: app.production.com
      paths:
        - path: /
          pathType: Prefix

# Mehrere Values-Dateien kombinieren
# (später überschreibt frühere)
helm install myapp ./myapp \
  -f values.yaml \
  -f values-production.yaml \
  --set secrets.databasePassword=$DB_PASSWORD

Dependencies verwalten

# Dependencies herunterladen
helm dependency update ./myapp

# Erstellt charts/ Ordner mit:
# charts/
# ├── postgresql-12.1.0.tgz
# └── redis-17.0.0.tgz

# Chart.lock wird erstellt (Versionen einfrieren)

# Dependencies auflisten
helm dependency list ./myapp

Chart testen

# Lint (Syntax prüfen)
helm lint ./myapp

# Template rendern und prüfen
helm template myapp ./myapp | kubectl apply --dry-run=client -f -

# Tests im Chart (templates/tests/)
# templates/tests/test-connection.yaml

apiVersion: v1
kind: Pod
metadata:
  name: "{{ include "myapp.fullname" . }}-test"
  annotations:
    "helm.sh/hook": test
spec:
  containers:
    - name: wget
      image: busybox
      command: ['wget']
      args: ['{{ include "myapp.fullname" . }}:{{ .Values.service.port }}']
  restartPolicy: Never

# Tests ausführen
helm test myapp

Chart veröffentlichen

# Chart packen
helm package ./myapp
# Erstellt: myapp-1.0.0.tgz

# Index erstellen (für Repository)
helm repo index . --url https://charts.example.com

# GitHub Pages als Helm Repo
# 1. charts/ Ordner mit .tgz Dateien
# 2. index.yaml generieren
# 3. GitHub Pages aktivieren

# OCI Registry (moderne Methode)
helm push myapp-1.0.0.tgz oci://registry.example.com/charts

# Aus OCI Registry installieren
helm install myapp oci://registry.example.com/charts/myapp --version 1.0.0

Hooks

# templates/job-migrate.yaml

apiVersion: batch/v1
kind: Job
metadata:
  name: {{ include "myapp.fullname" . }}-migrate
  annotations:
    "helm.sh/hook": pre-upgrade,pre-install
    "helm.sh/hook-weight": "-5"
    "helm.sh/hook-delete-policy": hook-succeeded
spec:
  template:
    spec:
      containers:
        - name: migrate
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          command: ["./migrate.sh"]
      restartPolicy: Never
  backoffLimit: 1

# Hook Types:
# pre-install, post-install
# pre-upgrade, post-upgrade
# pre-delete, post-delete
# pre-rollback, post-rollback

Weitere Informationen

• 🔄 GitOps mit ArgoCD
• 🚀 Rolling Updates
• 🐤 Canary Releases