【K8s】专题五（5）：Kubernetes 配置之热更新工具 Reloader

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目录

一、基本介绍

二、工作原理

三、部署方法

四、使用方法

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一、基本介绍

Reloader 是一个用于 Kubernetes 的工具，能够监听 Kubernetes 中 ConfigMap 和 Secret 的变化，并通过自动触发 Deployment、StatefulSet、Daemonset 等对象重启，实现应用程序配置的热更新（重新加载）。

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二、工作原理

• 监听配置：Reloader 会监听指定 ConfigMap 或 Secret 的配置文件
• 触发事件：当检测到配置文件内容发生变化时，Reloader 会触发一个事件
• 重新加载：Reloader 向控制器发送信号，请求重启 Deployment、StatefulSet、Daemonset 等对象

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三、部署方法

1、资源清单

# reloader.yaml
## 定义 RBAC 对象
apiVersion: v1
kind: ServiceAccount
metadata:
  name: reloader
 
---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: reloader-role
rules:
  - apiGroups:
      - ""
    resources:
      - secrets
      - configmaps
    verbs:
      - list
      - get
      - watch
  - apiGroups:
      - "apps"
    resources:
      - deployments
      - daemonsets
      - statefulsets
    verbs:
      - list
      - get
      - update
      - patch
  - apiGroups:
      - "extensions"
    resources:
      - deployments
      - daemonsets
    verbs:
      - list
      - get
      - update
      - patch
  - apiGroups:
      - ""
    resources:
      - events
    verbs:
      - create
      - patch
 
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: reloader-rolebinding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: reloader-role
subjects:
  - kind: ServiceAccount
    name: reloader
 
## 定义 Deployment 对象
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: reloader
spec:
  replicas: 1
  revisionHistoryLimit: 10
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
  selector:
    matchLabels:
      app: reloader
  template:
    metadata:
      labels:
        app: reloader
    spec:
      containers:
      - name: reloader
        image: stakater/reloader:v1.0.12
        imagePullPolicy: IfNotPresent
        ports:
        - name: http
          containerPort: 9090
        env:
        - name: KUBERNETES_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        startupProbe:
          httpGet:
            path: /metrics
            port: http
          initialDelaySeconds: 5
          periodSeconds: 5
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 10
        readinessProbe:
          httpGet:
            path: /metrics
            port: http
          initialDelaySeconds: 5
          periodSeconds: 5
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        livenessProbe:
          httpGet:
            path: /live
            port: http
          initialDelaySeconds: 5
          periodSeconds: 5
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        resources:
          limits:
            cpu: 200m
            memory: 200Mi
          requests:
            cpu: 20m
            memory: 20Mi
      restartPolicy: Always
      securityContext: 
        runAsNonRoot: true
        runAsUser: 65534
      serviceAccountName: reloader

2、部署命令

kubectl apply -f reloader.yaml

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四、使用方法

在 Deployment、StatefulSet、DaemonSet 等对象的资源清单中，添加相应的 Annotation 注解即可，示例如下：

apiVersion: apps/v1
kind: Deployment
metadata:
  nanme: demo-deployment
  annotations:
    reloader.stakater.com/auto: "true"
...
 
 
🔔 reloader.stakater.com/auto: "true"：对所有 ConfigMap 和 Secret 对象生效
🔔 configmap.reloader.stakater.com/reload: "demo1,demo2,..."：对指定的 ConfigMap 对象生效
🔔 secret.reloader.stakater.com/reload: "demo1,demo2,..."：对指定的 Secret 对象生效