pod资源的健康检查-readiness探针的httpGet使用

livenessProbe：健康状态检查，周期性检查服务是否存活，检查结果失败，将重启容器

readinessProbe：可用性检查，周期性检查服务是否可用，不可用将从service的endpoints中移除

同一个容器中，可以同时使用livenessProbe，readinessProbe。

都是使用httpGet方式，livenessProbe探针检测容器监控状态，readinessProbe探针服务可以性

[root@k8s-master1 tanzhen]# cat nginx-deploy2-httpGet.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: readiness
spec:
  replicas: 1
  selector:
    matchLabels:
      app: readiness
      version: v1
  template:
    metadata:
     labels:
      app: readiness
      version: v1
    spec:
       containers:
       - name: readiness
         image: centos-nginx:1.23.0
         imagePullPolicy: IfNotPresent
         livenessProbe:
           httpGet:
             path: /index.html
             port: 80
           initialDelaySeconds: 5
           periodSeconds: 10
         readinessProbe:
           httpGet:
             path: /index.html
             port: 80
           initialDelaySeconds: 5
           periodSeconds: 10

创建deployment

[root@k8s-master1 tanzhen]# kubectl apply -f nginx-deploy2-httpGet.yaml
deployment.apps/readiness created

创建svc，

[root@k8s-master1 tanzhen]# cat svc.yaml
apiVersion: v1
kind: Service
metadata:
  creationTimestamp: null
  name: readiness-svc
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: readiness
    version: v1
  type: NodePort
status:
  loadBalancer: {}

[root@k8s-master1 tanzhen]# kubectl apply -f svc.yaml
service/readiness-svc created

describe查询svc资源，可以看到Endpoints已经加入一个pod资源，如果探针检测到服务异常，就会吧对应的pod资源从Endpoints中剔除

[root@k8s-master1 tanzhen]# kubectl get svc
NAME            TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
kubernetes      ClusterIP   10.96.0.1        <none>        443/TCP        10d
my-dep          NodePort    10.103.136.43    <none>        80:31644/TCP   8d
readiness-svc   NodePort    10.108.113.163   <none>        80:30663/TCP   10m
[root@k8s-master1 tanzhen]#
[root@k8s-master1 tanzhen]#
[root@k8s-master1 tanzhen]# kubectl describe svc readiness-svc
Name:                     readiness-svc
Namespace:                default
Labels:                   <none>
Annotations:              <none>
Selector:                 app=readiness,version=v1
Type:                     NodePort
IP:                       10.108.113.163
Port:                     <unset>  80/TCP
TargetPort:               80/TCP
NodePort:                 <unset>  30663/TCP
Endpoints:                10.244.2.20:80
Session Affinity:         None
External Traffic Policy:  Cluster
Events:                   <none>