【k8s】svc-publishNotReadyAddresses

環境

1. kubernetes 1.20.4
2. Spring Boot 2.5.0-M3

目標

publishNotReadyAddresses 表示是否將沒有就緒的 Pod 的地址關聯到服務上。
默認情況是 false，只有就緒狀態的 Pod 的地址才會關聯到服務上。

示例

Deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: spring-k8s
spec:
  selector:
    matchLabels:
      app: spring-k8s
  template:
    metadata:
      labels:
        app: spring-k8s
    spec:
      containers:
        - name: spring-k8s
          image: jiangbo920827/spring-k8s:liveness
          readinessProbe:
            failureThreshold: 30
            exec:
              command: ["sh", "-c", "cat /root/test.txt"]
          ports:
            - containerPort: 8080

添加了一個就緒探針，因為這個文件不存在，所以 Pod 一直是未就緒，直到失敗。

查看 Pod

[root@master ~]# kubectl get pod
NAME                         READY   STATUS    RESTARTS   AGE
spring-k8s-d8ccf5994-zbxzg   0/1     Running   0          4m16s

Service.yaml

apiVersion: v1
kind: Service
metadata:
  name: spring-k8s
spec:
  selector:
    app: spring-k8s
  ports:
    - port: 80
      targetPort: 8080

查看不發布就緒

[root@master ~]# kubectl describe svc spring-k8s
Name:              spring-k8s
Namespace:         default
Labels:            <none>
Annotations:       <none>
Selector:          app=spring-k8s
Type:              ClusterIP
IP Families:       <none>
IP:                10.104.121.41
IPs:               10.104.121.41
Port:              <unset>  80/TCP
TargetPort:        8080/TCP
Endpoints:
Session Affinity:  None
Events:            <none>

發布未就緒 Pod

apiVersion: v1
kind: Service
metadata:
  name: spring-k8s
spec:
  selector:
    app: spring-k8s
  publishNotReadyAddresses: true
  ports:
    - port: 80
      targetPort: 8080

查看發布未就緒 Pod

[root@master ~]# kubectl describe svc spring-k8s
Name:              spring-k8s
Namespace:         default
Labels:            <none>
Annotations:       <none>
Selector:          app=spring-k8s
Type:              ClusterIP
IP Families:       <none>
IP:                10.104.121.41
IPs:               10.104.121.41
Port:              <unset>  80/TCP
TargetPort:        8080/TCP
Endpoints:         10.244.2.232:8080
Session Affinity:  None
Events:            <none>
[root@master ~]# kubectl get pod
NAME                         READY   STATUS    RESTARTS   AGE
spring-k8s-d8ccf5994-zbxzg   0/1     Running   0          7m16s

總結

publishNotReadyAddresses 可以控制是否將未就緒的 Pod 發布到 Service 上，一般不建議為 true。
如果 Pod 還未就緒的話，發送到上面的請求可能得不到正常的響應。

附錄