Helm 全景概览

什么是 Helm

Helm 是 Kubernetes 的包管理器，将一组 K8s 资源打包为 Chart，支持版本管理、参数化配置、依赖管理。

Chart（包）
├── Chart.yaml          # 元数据
├── values.yaml         # 默认配置
├── templates/          # K8s 资源模板
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   └── _helpers.tpl    # 模板辅助函数
├── charts/             # 依赖 Chart
└── README.md

快速开始

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

# 添加仓库
helm repo add stable https://charts.helm.sh/stable
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update

# 搜索 Chart
helm search repo nginx
helm search hub wordpress  # 搜索 Artifact Hub

# 安装
helm install my-nginx bitnami/nginx \
  --namespace production \
  --create-namespace \
  --set replicaCount=3 \
  --set service.type=LoadBalancer

# 查看安装状态
helm list -n production
helm status my-nginx -n production

# 升级
helm upgrade my-nginx bitnami/nginx \
  --namespace production \
  --set replicaCount=5 \
  --reuse-values  # 保留之前的 values

# 回滚
helm rollback my-nginx 1 -n production

# 卸载
helm uninstall my-nginx -n production

创建 Chart

# 创建 Chart 骨架
helm create my-app

# 目录结构
my-app/
├── Chart.yaml
├── values.yaml
├── templates/
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── hpa.yaml
│   ├── serviceaccount.yaml
│   ├── NOTES.txt          # 安装后显示的说明
│   └── _helpers.tpl
└── .helmignore

Chart.yaml

apiVersion: v2
name: my-app
description: 我的应用 Helm Chart
type: application  # application | library
version: 0.1.0     # Chart 版本
appVersion: "1.0.0"  # 应用版本

dependencies:
- name: postgresql
  version: "13.x.x"
  repository: https://charts.bitnami.com/bitnami
  condition: postgresql.enabled
- name: redis
  version: "18.x.x"
  repository: https://charts.bitnami.com/bitnami
  condition: redis.enabled

values.yaml

replicaCount: 1

image:
  repository: my-app
  pullPolicy: IfNotPresent
  tag: ""  # 默认使用 Chart.appVersion

serviceAccount:
  create: true
  name: ""

service:
  type: ClusterIP
  port: 80

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

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

autoscaling:
  enabled: false
  minReplicas: 1
  maxReplicas: 10
  targetCPUUtilizationPercentage: 80

postgresql:
  enabled: true
  auth:
    database: myapp
    username: myapp
    password: ""  # 生产环境通过 --set 传入

config:
  logLevel: info
  maxConnections: 100

模板语法

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "my-app.fullname" . }}
  labels:
    {{- include "my-app.labels" . | nindent 4 }}
spec:
  {{- if not .Values.autoscaling.enabled }}
  replicas: {{ .Values.replicaCount }}
  {{- end }}
  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 | default .Chart.AppVersion }}"
        imagePullPolicy: {{ .Values.image.pullPolicy }}
        ports:
        - containerPort: 8080
        env:
        - name: LOG_LEVEL
          value: {{ .Values.config.logLevel | quote }}
        {{- if .Values.postgresql.enabled }}
        - name: DB_HOST
          value: {{ include "my-app.fullname" . }}-postgresql
        {{- end }}
        resources:
          {{- toYaml .Values.resources | nindent 10 }}

常用命令

# 渲染模板（不安装，用于调试）
helm template my-app ./my-app -f custom-values.yaml

# 验证 Chart
helm lint ./my-app

# 打包 Chart
helm package ./my-app

# 推送到 OCI 仓库
helm push my-app-0.1.0.tgz oci://registry.example.com/charts

# 查看 Release 历史
helm history my-nginx -n production

# 获取当前 values
helm get values my-nginx -n production

# 获取渲染后的 manifest
helm get manifest my-nginx -n production