Belajar Kubernetes - Episode 38 - Pengenalan dan Penjelasan Helm Charts
Di episode ini kita akan coba bahas Helm Charts untuk packaging dan deploying Kubernetes application. Kita akan mempelajari bagaimana create, customize, dan deploy Helm chart, manage dependency, dan best practice untuk Helm.
#Pendahuluan
Catatan
Untuk kalian yang ingin membaca episode sebelumnya, bisa click thumbnail episode 37 di bawah ini
Episode 37Di episode sebelumnya, kita menjelajahi Pod Security Context, yang mengontrol pengaturan keamanan untuk Pod dan container. Sekarang kita akan mendalami Helm Charts, yang menyederhanakan packaging dan deploying aplikasi Kubernetes.
Catatan: Disini saya akan menggunakan Kubernetes Cluster yang di install melalui K3s.
Helm adalah package manager untuk Kubernetes. Ini memungkinkan Anda mendefinisikan, install, dan upgrade aplikasi Kubernetes yang kompleks menggunakan chart. Pikirkan Helm chart seperti Docker image untuk Kubernetes - mereka package semuanya yang diperlukan untuk menjalankan aplikasi. Daripada manage puluhan file YAML secara manual, Helm memungkinkan Anda template dan version deployment Anda.
#Memahami Helm Charts
Helm chart adalah koleksi file yang mendeskripsikan serangkaian resource Kubernetes. Ini pada dasarnya adalah package yang di-template yang dapat dikustomisasi dan di-deploy ke cluster.
#Mengapa Helm Charts Penting
1. Simplify Deployment
Package aplikasi kompleks menjadi single deployable unit.
2. Reusability
Share chart di seluruh tim dan organisasi.
3. Templating
Gunakan variable dan logic untuk customize deployment.
4. Versioning
Track dan manage berbagai versi aplikasi.
5. Dependency Management
Manage dependency antara aplikasi.
6. Rollback Capability
Easily rollback ke versi sebelumnya.
#Struktur Helm Chart
Typical Helm chart memiliki struktur ini:
my-chart/
├── Chart.yaml
├── values.yaml
├── values-prod.yaml
├── templates/
│ ├── deployment.yaml
│ ├── service.yaml
│ ├── configmap.yaml
│ ├── ingress.yaml
│ └── _helpers.tpl
├── charts/
│ └── dependency-chart/
└── README.md#Chart.yaml
Metadata tentang chart:
apiVersion: v2
name: my-app
description: A Helm chart for my application
type: application
version: 1.0.0
appVersion: "1.0"
keywords:
- app
- kubernetes
maintainers:
- name: Your Name
email: your@email.com#values.yaml
Default configuration value:
replicaCount: 3
image:
repository: myapp
tag: "1.0"
pullPolicy: IfNotPresent
service:
type: ClusterIP
port: 80
targetPort: 8080
ingress:
enabled: true
className: nginx
hosts:
- host: myapp.example.com
paths:
- path: /
pathType: Prefix
resources:
limits:
cpu: 500m
memory: 512Mi
requests:
cpu: 250m
memory: 256Mi#Templates
Kubernetes manifest dengan template variable:
apiVersion: apps/v1
kind: Deployment
metadata:
name: {{ include "my-app.fullname" . }}
labels:
{{- include "my-app.labels" . | nindent 4 }}
spec:
replicas: {{ .Values.replicaCount }}
selector:
matchLabels:
{{- include "my-app.selectorLabels" . | nindent 6 }}
template:
metadata:
labels:
{{- include "my-app.selectorLabels" . | nindent 8 }}
spec:
containers:
- name: {{ .Chart.Name }}
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
imagePullPolicy: {{ .Values.image.pullPolicy }}
ports:
- name: http
containerPort: {{ .Values.service.targetPort }}
protocol: TCP
resources:
{{- toYaml .Values.resources | nindent 12 }}#Membuat Helm Chart
#Initialize Chart
helm create my-appIni membuat basic chart structure dengan example file.
#Chart Validation
helm lint my-appValidate chart untuk error.
#Template Rendering
helm template my-app ./my-appMenunjukkan rendered YAML tanpa install.
#Dry Run
helm install my-release ./my-app --dry-run --debugSimulate installation tanpa actually deploy.
#Install Helm Charts
#Basic Installation
helm install my-release ./my-appInstall chart dengan default value.
#Custom Values
helm install my-release ./my-app -f values-prod.yamlInstall dengan custom value dari file.
#Override Values
helm install my-release ./my-app \
--set replicaCount=5 \
--set image.tag=2.0Override specific value dari command line.
#Namespace
helm install my-release ./my-app -n production --create-namespaceInstall di specific namespace.
#Manage Helm Release
#List Release
helm list
helm list -n productionMenunjukkan semua installed release.
#Get Release Info
helm status my-release
helm get values my-release
helm get manifest my-releaseMenunjukkan release status dan configuration.
#Upgrade Release
helm upgrade my-release ./my-appUpgrade ke versi baru.
#Rollback Release
helm rollback my-release 1Rollback ke previous revision.
#Uninstall Release
helm uninstall my-releaseRemove release dari cluster.
#Helm Repository
#Add Repository
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo updateAdd Helm repository dan update index.
#Search Charts
helm search repo bitnami
helm search repo bitnami/nginxSearch chart di repository.
#Install from Repository
helm install my-nginx bitnami/nginxInstall chart dari repository.
#Popular Repository
- Bitnami - https://charts.bitnami.com/bitnami
- Stable - https://charts.helm.sh/stable
- Jetstack - https://charts.jetstack.io (cert-manager)
- Prometheus - https://prometheus-community.github.io/helm-charts
#Template Function
#Built-in Function
# String function
{{ .Values.name | upper }}
{{ .Values.name | lower }}
{{ .Values.name | quote }}
# Conditional
{{ if .Values.enabled }}
enabled: true
{{ end }}
# Loops
{{ range .Values.items }}
- {{ . }}
{{ end }}
# Default value
{{ .Values.name | default "default-name" }}
# Include template
{{ include "my-app.labels" . }}#Helper Template
{{/*
Expand the name of the chart.
*/}}
{{- define "my-app.name" -}}
{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
{{- end }}
{{/*
Create a default fully qualified app name.
*/}}
{{- define "my-app.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 "my-app.labels" -}}
helm.sh/chart: {{ include "my-app.chart" . }}
{{ include "my-app.selectorLabels" . }}
{{- if .Chart.AppVersion }}
app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
{{- end }}
app.kubernetes.io/managed-by: {{ .Release.Service }}
{{- end }}
{{/*
Selector labels
*/}}
{{- define "my-app.selectorLabels" -}}
app.kubernetes.io/name: {{ include "my-app.name" . }}
app.kubernetes.io/instance: {{ .Release.Name }}
{{- end }}#Chart Dependency
#Chart.yaml dengan Dependency
apiVersion: v2
name: my-app
version: 1.0.0
dependencies:
- name: postgresql
version: "12.0.0"
repository: "https://charts.bitnami.com/bitnami"
condition: postgresql.enabled
- name: redis
version: "17.0.0"
repository: "https://charts.bitnami.com/bitnami"
condition: redis.enabled#Update Dependency
helm dependency update ./my-appDownload dan update chart dependency.
#values.yaml dengan Dependency
postgresql:
enabled: true
auth:
username: myapp
password: secret
database: myapp_db
redis:
enabled: true
auth:
enabled: false#Contoh Praktis
#Simple Web Application Chart
apiVersion: apps/v1
kind: Deployment
metadata:
name: {{ include "web-app.fullname" . }}
spec:
replicas: {{ .Values.replicaCount }}
selector:
matchLabels:
app: {{ include "web-app.name" . }}
template:
metadata:
labels:
app: {{ include "web-app.name" . }}
spec:
containers:
- name: web
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
ports:
- containerPort: {{ .Values.service.port }}
env:
- name: DATABASE_URL
valueFrom:
secretKeyRef:
name: {{ include "web-app.fullname" . }}-secret
key: database-url
resources:
{{- toYaml .Values.resources | nindent 12 }}
---
apiVersion: v1
kind: Service
metadata:
name: {{ include "web-app.fullname" . }}
spec:
type: {{ .Values.service.type }}
ports:
- port: {{ .Values.service.port }}
targetPort: {{ .Values.service.port }}
selector:
app: {{ include "web-app.name" . }}#Conditional Resource
{{- if .Values.ingress.enabled }}
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: {{ include "web-app.fullname" . }}
spec:
ingressClassName: {{ .Values.ingress.className }}
rules:
{{- range .Values.ingress.hosts }}
- host: {{ .host | quote }}
http:
paths:
{{- range .paths }}
- path: {{ .path }}
pathType: {{ .pathType }}
backend:
service:
name: {{ include "web-app.fullname" . }}
port:
number: {{ $.Values.service.port }}
{{- end }}
{{- end }}
{{- end }}#Kesalahan dan Jebakan Umum
#Kesalahan 1: Hardcoding Value
Problem: Chart tidak reusable.
# JANGAN LAKUKAN INI - Hardcoded value
image: myapp:1.0
replicas: 3Solusi: Gunakan template variable:
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
replicas: {{ .Values.replicaCount }}#Kesalahan 2: Missing Default Value
Problem: Chart gagal jika value tidak disediakan.
# JANGAN LAKUKAN INI - No default value
image: "{{ .Values.image }}"Solusi: Provide default:
image: "{{ .Values.image | default "nginx:latest" }}"#Kesalahan 3: Inconsistent Naming
Problem: Resource memiliki inconsistent name.
# JANGAN LAKUKAN INI - Inconsistent naming
metadata:
name: my-app
---
metadata:
name: myappSolusi: Gunakan helper template:
metadata:
name: {{ include "my-app.fullname" . }}#Kesalahan 4: Not Testing Chart
Problem: Chart memiliki error ketika di-deploy.
Solusi: Selalu test sebelum deploy:
helm lint ./my-app
helm template ./my-app
helm install --dry-run --debug ./my-app#Kesalahan 5: Poor Documentation
Problem: User tidak tahu bagaimana menggunakan chart.
Solusi: Document value dan usage:
# My App Helm Chart
## Installation
```bash
helm install my-release ./my-app
```
## Configuration
| Parameter | Description | Default |
|-----------|-------------|---------|
| replicaCount | Number of replicas | 3 |
| image.repository | Image repository | myapp |
| image.tag | Image tag | 1.0 |#Praktik Terbaik
#1. Gunakan Semantic Versioning
version: 1.2.3
appVersion: "2.0.1"#2. Provide Comprehensive values.yaml
Document semua available value dengan comment:
# Number of replicas
replicaCount: 3
# Image configuration
image:
# Image repository
repository: myapp
# Image tag
tag: "1.0"
# Image pull policy
pullPolicy: IfNotPresent#3. Gunakan Helper Template
Create reusable template helper:
{{- define "my-app.fullname" -}}
{{- .Release.Name }}-{{ .Chart.Name }}
{{- end }}#4. Validate Chart
Selalu validate sebelum deploy:
helm lint ./my-app
helm template ./my-app#5. Gunakan Namespace
Deploy ke specific namespace:
helm install my-release ./my-app -n production --create-namespace#6. Version Your Chart
Track chart version di version control:
git tag chart-v1.0.0#7. Document Value
Create comprehensive README:
# Chart Documentation
## Value
- `replicaCount`: Number of replicas (default: 3)
- `image.repository`: Image repository (default: myapp)
- `image.tag`: Image tag (default: 1.0)#Helm Hook
Execute action di specific point di release lifecycle:
apiVersion: batch/v1
kind: Job
metadata:
name: {{ include "my-app.fullname" . }}-pre-install
annotations:
"helm.sh/hook": pre-install
"helm.sh/hook-weight": "-5"
spec:
template:
spec:
containers:
- name: pre-install
image: busybox
command: ['sh', '-c', 'echo "Pre-install hook"']
restartPolicy: Never#Hook Type
pre-install- Before installpost-install- After installpre-upgrade- Before upgradepost-upgrade- After upgradepre-delete- Before deletepost-delete- After deletepre-rollback- Before rollbackpost-rollback- After rollback
#Kesimpulan
Pada episode 38 ini, kita telah membahas Helm Charts di Kubernetes secara mendalam. Kita sudah belajar bagaimana create, customize, dan deploy Helm chart, manage dependency, dan follow best practice.
Key takeaway:
- Helm Charts package Kubernetes application
- Chart.yaml - Chart metadata
- values.yaml - Default configuration
- templates/ - Kubernetes manifest dengan variable
- helm create - Initialize chart baru
- helm install - Deploy chart
- helm upgrade - Update release
- helm rollback - Revert ke previous version
- Template function - Customize deployment
- Dependency - Manage chart dependency
- Repository - Share dan discover chart
- Hook - Execute action di lifecycle event
- Selalu validate - Test chart sebelum deploy
- Document value - Help user understand configuration
- Gunakan semantic versioning - Track chart version
Helm chart menyederhanakan Kubernetes deployment dan membuat aplikasi lebih reusable dan maintainable.
Catatan
Untuk kalian yang ingin melanjutkan ke episode selanjutnya, bisa click thumbnail episode 38 di bawah ini
Episode 38