securing-helm-chart-deployments

保护 Helm Chart 部署

概述

Helm 是 Kubernetes 的包管理器。保护 Helm 部署需要验证 Chart 来源、扫描模板中的安全配置错误、强制实施 Pod 安全上下文、安全管理密钥，以及控制 Helm 操作的 RBAC。

适用场景

• 在环境中部署或配置保护 Helm Chart 部署功能时
• 制定符合合规要求的安全控制措施时
• 构建或改进此领域的安全架构时
• 开展需要此实现方案的安全评估时

前提条件

• 已安装 Helm 3.12+
• 已安装可访问集群的 kubectl
• 用于 Chart 签名和验证的 GnuPG
• 用于扫描模板的 kubesec 或 checkov

Chart 来源与完整性

为 Helm Chart 签名

# Generate GPG key for signing
gpg --full-generate-key

# Package and sign chart
helm package ./mychart --sign --key "[email protected]" --keyring ~/.gnupg/pubring.gpg

# Verify chart signature
helm verify mychart-0.1.0.tgz --keyring ~/.gnupg/pubring.gpg

安装前验证 Chart

# Verify chart from repository
helm pull myrepo/mychart --verify --keyring /path/to/keyring.gpg

# Check chart provenance file
cat mychart-0.1.0.tgz.prov

模板安全扫描

渲染并扫描模板

# Render templates without deploying
helm template myrelease ./mychart --values values-prod.yaml > rendered.yaml

# Scan with kubesec
kubesec scan rendered.yaml

# Scan with checkov
checkov -f rendered.yaml --framework kubernetes

# Scan with trivy
trivy config rendered.yaml

# Scan with kube-linter
kube-linter lint rendered.yaml

使用 Helm lint 检查配置错误

# Lint chart
helm lint ./mychart --values values-prod.yaml --strict

# Lint with debug output
helm lint ./mychart --debug

在 values.yaml 中强制实施安全上下文

# values.yaml - Security hardened defaults
securityContext:
  runAsNonRoot: true
  runAsUser: 1000
  runAsGroup: 3000
  fsGroup: 2000
  readOnlyRootFilesystem: true
  allowPrivilegeEscalation: false
  capabilities:
    drop:
      - ALL

podSecurityContext:
  seccompProfile:
    type: RuntimeDefault

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

networkPolicy:
  enabled: true

serviceAccount:
  create: true
  automountServiceAccountToken: false

image:
  pullPolicy: Always
  # Use digest instead of tag for immutability
  # tag: "1.0.0"
  # digest: "sha256:abc123..."

配置安全上下文的模板

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "mychart.fullname" . }}
spec:
  template:
    spec:
      automountServiceAccountToken: {{ .Values.serviceAccount.automountServiceAccountToken }}
      securityContext:
        {{- toYaml .Values.podSecurityContext | nindent 8 }}
      containers:
        - name: {{ .Chart.Name }}
          securityContext:
            {{- toYaml .Values.securityContext | nindent 12 }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          resources:
            {{- toYaml .Values.resources | nindent 12 }}

密钥管理

使用外部密钥（不要使用 Helm values）

# templates/external-secret.yaml
apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: {{ include "mychart.fullname" . }}-secrets
spec:
  refreshInterval: 1h
  secretStoreRef:
    name: aws-secretsmanager
    kind: ClusterSecretStore
  target:
    name: {{ include "mychart.fullname" . }}-secrets
  data:
    - secretKey: db-password
      remoteRef:
        key: production/database
        property: password

helm-secrets 插件

# Install helm-secrets plugin
helm plugin install https://github.com/jkroepke/helm-secrets

# Encrypt values file
helm secrets encrypt values-secrets.yaml

# Deploy with encrypted secrets
helm secrets install myrelease ./mychart -f values.yaml -f values-secrets.yaml

# Decrypt for editing
helm secrets edit values-secrets.yaml

Helm 操作的 RBAC

# helm-deployer-role.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: helm-deployer
  namespace: production
rules:
  - apiGroups: ["", "apps", "batch", "networking.k8s.io"]
    resources: ["deployments", "services", "configmaps", "secrets", "ingresses", "jobs"]
    verbs: ["get", "list", "create", "update", "patch", "delete"]
  - apiGroups: [""]
    resources: ["pods", "pods/log"]
    verbs: ["get", "list"]

---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: helm-deployer-binding
  namespace: production
subjects:
  - kind: ServiceAccount
    name: helm-deployer
    namespace: production
roleRef:
  kind: Role
  name: helm-deployer
  apiGroup: rbac.authorization.k8s.io

CI/CD Helm 安全流水线

# .github/workflows/helm-security.yaml
name: Helm Chart Security
on:
  pull_request:
    paths: ['charts/**']

jobs:
  lint-and-scan:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Helm lint
        run: helm lint ./charts/mychart --strict

      - name: Render templates
        run: helm template test ./charts/mychart -f charts/mychart/values.yaml > rendered.yaml

      - name: Scan with kube-linter
        uses: stackrox/kube-linter-action@v1
        with:
          directory: rendered.yaml

      - name: Scan with trivy
        uses: aquasecurity/trivy-action@master
        with:
          scan-type: config
          scan-ref: rendered.yaml

      - name: Scan with checkov
        uses: bridgecrewio/checkov-action@master
        with:
          file: rendered.yaml
          framework: kubernetes

最佳实践

1. 使用 GPG 为 Chart 签名，并在安装前验证
2. 在部署前渲染并扫描模板，以发现配置错误
3. 在 values.yaml 默认值中强制实施安全上下文
4. 切勿在 Helm values 中存储密钥——请使用外部密钥或 helm-secrets 插件
5. 使用镜像摘要代替标签，确保引用不可变
6. 将 Helm RBAC 限制为每个命名空间所需的最小权限
7. 固定 requirements 中的 Chart 版本——切勿使用 latest
8. 在 CI 中使用 --strict 标志进行严格 lint 检查
9. 在部署到生产环境前审查第三方 Chart
10. 使用 Helm 测试钩子在安装后验证部署