kubernetes系列教程（八）Pod健康检查机制

写在前面

上一篇文章中kubernetes系列教程（七）深入玩转pod调度介绍了kubernetes中Pod的调度机制，通过实战演练介绍Pod调度到node的几种方法：1. 通过nodeName固定选择调度，2. 通过nodeSelector定向选择调度，3. 通过node Affinity亲和力调度，接下来介绍kubernetes系列教程pod的健康检查机制。

1. 健康检查

1.1 健康检查概述

应用在运行过程中难免会出现错误，如程序异常，软件异常，硬件故障，网络故障等，kubernetes提供Health Check健康检查机制，当发现应用异常时会自动重启容器，将应用从service服务中剔除，保障应用的高可用性。k8s定义了三种探针Probe：

• readiness probes 准备就绪检查，通过readiness是否准备接受流量，准备完毕加入到endpoint，否则剔除
• liveness probes 在线检查机制，检查应用是否可用，如死锁，无法响应，异常时会自动重启容器
• startup probes 启动检查机制，应用一些启动缓慢的业务，避免业务长时间启动而被前面的探针kill掉

每种探测机制支持三种健康检查方法，分别是命令行exec，httpGet和tcpSocket，其中exec通用性最强，适用与大部分场景，tcpSocket适用于TCP业务，httpGet适用于web业务。

• exec 提供命令或shell的检测，在容器中执行命令检查，返回码为0健康，非0异常
• httpGet http协议探测，在容器中发送http请求，根据http返回码判断业务健康情况
• tcpSocket tcp协议探测，向容器发送tcp建立连接，能建立则说明正常

每种探测方法能支持几个相同的检查参数，用于设置控制检查时间：

• initialDelaySeconds 初始第一次探测间隔，用于应用启动的时间，防止应用还没启动而健康检查失败
• periodSeconds 检查间隔，多久执行probe检查，默认为10s
• timeoutSeconds 检查超时时长，探测应用timeout后为失败
• successThreshold 成功探测阈值，表示探测多少次为健康正常，默认探测1次

1.2 exec命令行健康检查

许多应用程序运行过程中无法检测到内部故障，如死锁，出现故障时通过重启业务可以恢复，kubernetes提供liveness在线健康检查机制，我们以exec为例，创建一个容器启动过程中创建一个文件/tmp/liveness-probe.log，10s后将其删除，定义liveness健康检查机制在容器中执行命令ls -l /tmp/liveness-probe.log，通过文件的返回码判断健康状态，如果返回码非0，暂停20s后kubelet会自动将该容器重启。

1. 定义一个容器，启动时创建一个文件，健康检查时ls -l /tmp/liveness-probe.log返回码为0，健康检查正常，10s后将其删除，返回码为非0，健康检查异常

[root@node-1 demo]# cat centos-exec-liveness-probe.yamlapiVersion: v1kind: Podmetadata:  name: exec-liveness-probe  annotations:    kubernetes.io/description: "exec-liveness-probe"spec:  containers:  - name: exec-liveness-probe    image: centos:latest    imagePullPolicy: IfNotPresent    args:    #容器启动命令，生命周期为30s    - /bin/sh    - -c    - touch /tmp/liveness-probe.log && sleep 10 && rm -f /tmp/liveness-probe.log && sleep 20    livenessProbe:      exec:  #健康检查机制，通过ls -l /tmp/liveness-probe.log返回码判断容器的健康状态        command:        - ls         - l         - /tmp/liveness-probe.log      initialDelaySeconds: 1      periodSeconds: 5      timeoutSeconds: 1

2. 应用配置生成容器

[root@node-1 demo]# kubectl apply -f centos-exec-liveness-probe.yaml pod/exec-liveness-probe created

3. 查看容器的event日志，容器启动后，10s以内容器状态正常，11s开始执行liveness健康检查，检查异常，触发容器重启

[root@node-1 demo]# kubectl describe pods exec-liveness-probe | tailEvents:  Type     Reason     Age                From               Message  ----     ------     ----               ----               -------  Normal   Scheduled  28s                default-scheduler  Successfully assigned default/exec-liveness-probe to node-3  Normal   Pulled     27s                kubelet, node-3    Container image "centos:latest" already present on machine  Normal   Created    27s                kubelet, node-3    Created container exec-liveness-probe  Normal   Started    27s                kubelet, node-3    Started container exec-liveness-probe  #容器已启动  Warning  Unhealthy  20s (x2 over 25s)  kubelet, node-3    Liveness probe failed: /tmp/liveness-probe.logls: cannot access l: No such file or directory #执行健康检查，检查异常  Warning  Unhealthy  15s  kubelet, node-3  Liveness probe failed: ls: cannot access l: No such file or directoryls: cannot access /tmp/liveness-probe.log: No such file or directory  Normal  Killing  15s  kubelet, node-3  Container exec-liveness-probe failed liveness probe, will be restarted  #重启容器

4. 查看容器重启次数，容器不停的执行，重启次数会响应增加，可以看到RESTARTS的次数在持续增加

[root@node-1 demo]# kubectl get pods exec-liveness-probe NAME                  READY   STATUS    RESTARTS   AGEexec-liveness-probe   1/1     Running   6          5m19s

1.3 httpGet健康检查

1. httpGet probe主要主要用于web场景，通过向容器发送http请求，根据返回码判断容器的健康状态，返回码小于4xx即表示健康，如下定义一个nginx应用，通过探测http://:port/index.html的方式判断健康状态

[root@node-1 demo]# cat nginx-httpGet-liveness-readiness.yaml apiVersion: v1kind: Podmetadata:  name: nginx-httpget-livess-readiness-probe   annotations:    kubernetes.io/description: "nginx-httpGet-livess-readiness-probe"spec:  containers:  - name: nginx-httpget-livess-readiness-probe    image: nginx:latest    ports:    - name: http-80-port      protocol: TCP      containerPort: 80    livenessProbe:   #健康检查机制，通过httpGet实现实现检查      httpGet:        port: 80        scheme: HTTP        path: /index.html      initialDelaySeconds: 3      periodSeconds: 10      timeoutSeconds: 3

2. 生成pod并查看健康状态

[root@node-1 demo]# kubectl apply -f nginx-httpGet-liveness-readiness.yaml pod/nginx-httpget-livess-readiness-probe created[root@node-1 demo]# kubectl get pods nginx-httpget-livess-readiness-probe NAME                                   READY   STATUS    RESTARTS   AGEnginx-httpget-livess-readiness-probe   1/1     Running   0          6s

3. 模拟故障，将pod中的path文件所属文件删除，此时发送http请求时会健康检查异常，会触发容器自动重启

查询pod所属的节点[root@node-1 demo]# kubectl get pods nginx-httpget-livess-readiness-probe -o wide NAME                                   READY   STATUS    RESTARTS   AGE    IP            NODE     NOMINATED NODE   READINESS GATESnginx-httpget-livess-readiness-probe   1/1     Running   1          3m9s   10.244.2.19   node-3              登录到pod中将文件删除[root@node-1 demo]# kubectl exec -it nginx-httpget-livess-readiness-probe /bin/bashroot@nginx-httpget-livess-readiness-probe:/# ls -l /usr/share/nginx/html/index.html -rw-r--r-- 1 root root 612 Sep 24 14:49 /usr/share/nginx/html/index.htmlroot@nginx-httpget-livess-readiness-probe:/# rm -f /usr/share/nginx/html/index.html 

4. 再次查看pod的列表，此时会RESTART的次数会增加1，表示重启重启过一次，AGE则多久前重启的时间

[root@node-1 demo]# kubectl get pods nginx-httpget-livess-readiness-probe NAME                                   READY   STATUS    RESTARTS   AGEnginx-httpget-livess-readiness-probe   1/1     Running   1          4m22s

5. 查看pod的详情，观察容器重启的情况，通过Liveness 检查容器出现404错误，触发重启。

[root@node-1 demo]# kubectl describe pods nginx-httpget-livess-readiness-probe | tailEvents:  Type     Reason     Age                    From               Message  ----     ------     ----                   ----               -------  Normal   Scheduled  5m45s                  default-scheduler  Successfully assigned default/nginx-httpget-livess-readiness-probe to node-3  Normal   Pulling    3m29s (x2 over 5m45s)  kubelet, node-3    Pulling image "nginx:latest"  Warning  Unhealthy  3m29s (x3 over 3m49s)  kubelet, node-3    Liveness probe failed: HTTP probe failed with statuscode: 404  Normal   Killing    3m29s                  kubelet, node-3    Container nginx-httpget-livess-readiness-probe failed liveness probe, will be restarted  Normal   Pulled     3m25s (x2 over 5m41s)  kubelet, node-3    Successfully pulled image "nginx:latest"  Normal   Created    3m25s (x2 over 5m40s)  kubelet, node-3    Created container nginx-httpget-livess-readiness-probe  Normal   Started    3m25s (x2 over 5m40s)  kubelet, node-3    Started container nginx-httpget-livess-readiness-probe

1.4 tcpSocket健康检查

1. tcpsocket健康检查适用于TCP业务，通过向指定容器建立一个tcp连接，可以建立连接则健康检查正常，否则健康检查异常，依旧以nignx为例使用tcp健康检查机制，探测80端口的连通性

[root@node-1 demo]# cat nginx-tcp-liveness.yaml apiVersion: v1kind: Podmetadata:  name: nginx-tcp-liveness-probe  annotations:    kubernetes.io/description: "nginx-tcp-liveness-probe"spec:  containers:  - name: nginx-tcp-liveness-probe     image: nginx:latest    ports:    - name: http-80-port      protocol: TCP      containerPort: 80    livenessProbe:  #健康检查为tcpSocket，探测TCP 80端口      tcpSocket:       port: 80      initialDelaySeconds: 3      periodSeconds: 10      timeoutSeconds: 3

2. 应用配置创建容器

[root@node-1 demo]# kubectl apply -f nginx-tcp-liveness.yaml pod/nginx-tcp-liveness-probe created[root@node-1 demo]# kubectl get pods nginx-tcp-liveness-probe NAME                       READY   STATUS    RESTARTS   AGEnginx-tcp-liveness-probe   1/1     Running   0          6s

3. 模拟故障，获取pod所属节点，登录到pod中，安装查看进程工具htop

获取pod所在node[root@node-1 demo]# kubectl get pods nginx-tcp-liveness-probe -o wide NAME                       READY   STATUS    RESTARTS   AGE   IP            NODE     NOMINATED NODE   READINESS GATESnginx-tcp-liveness-probe   1/1     Running   0          99s   10.244.2.20   node-3              登录到pod中[root@node-1 demo]# kubectl exec -it nginx-httpget-livess-readiness-probe /bin/bash#执行apt-get update更新和apt-get install htop安装工具root@nginx-httpget-livess-readiness-probe:/# apt-get update      Get:1 http://cdn-fastly.deb.debian.org/debian buster InRelease [122 kB]             Get:2 http://security-cdn.debian.org/debian-security buster/updates InRelease [39.1 kB]     Get:3 http://cdn-fastly.deb.debian.org/debian buster-updates InRelease [49.3 kB]            Get:4 http://security-cdn.debian.org/debian-security buster/updates/main amd64 Packages [95.7 kB]Get:5 http://cdn-fastly.deb.debian.org/debian buster/main amd64 Packages [7899 kB]Get:6 http://cdn-fastly.deb.debian.org/debian buster-updates/main amd64 Packages [5792 B]Fetched 8210 kB in 3s (3094 kB/s)Reading package lists... Doneroot@nginx-httpget-livess-readiness-probe:/# apt-get install htopReading package lists... DoneBuilding dependency tree       Reading state information... DoneSuggested packages:  lsof straceThe following NEW packages will be installed:  htop0 upgraded, 1 newly installed, 0 to remove and 5 not upgraded.Need to get 92.8 kB of archives.After this operation, 230 kB of additional disk space will be used.Get:1 http://cdn-fastly.deb.debian.org/debian buster/main amd64 htop amd64 2.2.0-1+b1 [92.8 kB]Fetched 92.8 kB in 0s (221 kB/s)debconf: delaying package configuration, since apt-utils is not installedSelecting previously unselected package htop.(Reading database ... 7203 files and directories currently installed.)Preparing to unpack .../htop_2.2.0-1+b1_amd64.deb ...Unpacking htop (2.2.0-1+b1) ...Setting up htop (2.2.0-1+b1) ...

4. 运行htop查看进程，容器进程通常为1

5. kill掉进程观察容器状态，观察RESTART次数重启次数增加

root@nginx-httpget-livess-readiness-probe:/# kill 1root@nginx-httpget-livess-readiness-probe:/# command terminated with exit code 137查看pod情况[root@node-1 demo]# kubectl get pods nginx-tcp-liveness-probe NAME                       READY   STATUS    RESTARTS   AGEnginx-tcp-liveness-probe   1/1     Running   1          13m

6. 查看容器详情，发现容器有重启的记录

[root@node-1 demo]# kubectl describe pods nginx-tcp-liveness-probe | tailTolerations:     node.kubernetes.io/not-ready:NoExecute for 300s                 node.kubernetes.io/unreachable:NoExecute for 300sEvents:  Type    Reason     Age                From               Message  ----    ------     ----               ----               -------  Normal  Scheduled  14m                default-scheduler  Successfully assigned default/nginx-tcp-liveness-probe to node-3  Normal  Pulling    44s (x2 over 14m)  kubelet, node-3    Pulling image "nginx:latest"  Normal  Pulled     40s (x2 over 14m)  kubelet, node-3    Successfully pulled image "nginx:latest"  Normal  Created    40s (x2 over 14m)  kubelet, node-3    Created container nginx-tcp-liveness-probe  Normal  Started    40s (x2 over 14m)  kubelet, node-3    Started container nginx-tcp-liveness-probe

1.5 readiness健康就绪

就绪检查用于应用接入到service的场景，用于判断应用是否已经就绪完毕，即是否可以接受外部转发的流量，健康检查正常则将pod加入到service的endpoints中，健康检查异常则从service的endpoints中删除，避免影响业务的访问。

1. 创建一个pod，使用httpGet的健康检查机制，定义readiness就绪检查探针检查路径/test.html

[root@node-1 demo]# cat httpget-liveness-readiness-probe.yaml apiVersion: v1kind: Podmetadata:  name: nginx-tcp-liveness-probe  annotations:    kubernetes.io/description: "nginx-tcp-liveness-probe"  labels:  #需要定义labels，后面定义的service需要调用    app: nginxspec:  containers:  - name: nginx-tcp-liveness-probe     image: nginx:latest    ports:    - name: http-80-port      protocol: TCP      containerPort: 80    livenessProbe:  #存活检查探针      httpGet:        port: 80        path: /index.html        scheme: HTTP      initialDelaySeconds: 3      periodSeconds: 10      timeoutSeconds: 3    readinessProbe:  #就绪检查探针      httpGet:        port: 80        path: /test.html        scheme: HTTP      initialDelaySeconds: 3      periodSeconds: 10      timeoutSeconds: 3

2. 定义一个service，将上述的pod加入到service中，注意使用上述定义的labels，app=nginx

[root@node-1 demo]# cat nginx-service.yamlapiVersion: v1kind: Servicemetadata:  labels:    app: nginx  name: nginx-service spec:  ports:  - name: http    port: 80     protocol: TCP    targetPort: 80  selector:    app: nginx   type: ClusterIP

3. 生成配置

[root@node-1 demo]# kubectl apply -f httpget-liveness-readiness-probe.yaml pod/nginx-tcp-liveness-probe created[root@node-1 demo]# kubectl apply -f nginx-service.yaml service/nginx-service created

4. 此时pod状态正常，此时readiness健康检查异常

[root@node-1 ~]# kubectl get pods nginx-httpget-livess-readiness-probe NAME                                   READY   STATUS    RESTARTS   AGEnginx-httpget-livess-readiness-probe   1/1     Running   2          153m#readiness健康检查异常，404报错（最后一行）[root@node-1 demo]# kubectl describe pods nginx-tcp-liveness-probe | tail                 node.kubernetes.io/unreachable:NoExecute for 300sEvents:  Type     Reason     Age                 From               Message  ----     ------     ----                ----               -------  Normal   Scheduled  2m6s                default-scheduler  Successfully assigned default/nginx-tcp-liveness-probe to node-3  Normal   Pulling    2m5s                kubelet, node-3    Pulling image "nginx:latest"  Normal   Pulled     2m1s                kubelet, node-3    Successfully pulled image "nginx:latest"  Normal   Created    2m1s                kubelet, node-3    Created container nginx-tcp-liveness-probe  Normal   Started    2m1s                kubelet, node-3    Started container nginx-tcp-liveness-probe  Warning  Unhealthy  2s (x12 over 112s)  kubelet, node-3    Readiness probe failed: HTTP probe failed with statuscode: 404

5. 查看services的endpoints，发现此时endpoints为空,因为readiness就绪检查异常，kubelet认为此时pod并未就绪，因此并未将其加入到endpoints中。

[root@node-1 ~]# kubectl describe services nginx-service Name:              nginx-serviceNamespace:         defaultLabels:            app=nginxAnnotations:       kubectl.kubernetes.io/last-applied-configuration:                     {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"nginx"},"name":"nginx-service","namespace":"default"},"s...Selector:          app=nginxType:              ClusterIPIP:                10.110.54.40Port:              http  80/TCPTargetPort:        80/TCPEndpoints:          #Endpoints对象为空Session Affinity:  NoneEvents:            #endpoints状态[root@node-1 demo]# kubectl describe endpoints nginx-service Name:         nginx-serviceNamespace:    defaultLabels:       app=nginxAnnotations:  endpoints.kubernetes.io/last-change-trigger-time: 2019-09-30T14:27:37ZSubsets:  Addresses:            NotReadyAddresses:  10.244.2.22  #pod处于NotReady状态  Ports:    Name  Port  Protocol    ----  ----  --------    http  80    TCPEvents:  

6. 进入到pod中手动创建网站文件，使readiness健康检查正常

[root@node-1 ~]# kubectl exec -it nginx-httpget-livess-readiness-probe /bin/bashroot@nginx-httpget-livess-readiness-probe:/# echo "readiness probe demo" >/usr/share/nginx/html/test.html

7. 此时readiness健康检查正常，kubelet检测到pod就绪会将其加入到endpoints中

健康检查正常[root@node-1 demo]# curl http://10.244.2.22/test.html查看endpoints情况readines[root@node-1 demo]# kubectl describe endpoints nginx-service Name:         nginx-serviceNamespace:    defaultLabels:       app=nginxAnnotations:  endpoints.kubernetes.io/last-change-trigger-time: 2019-09-30T14:33:01ZSubsets:  Addresses:          10.244.2.22 #就绪地址，已从NotReady中提出，加入到正常的Address列表中  NotReadyAddresses:    Ports:    Name  Port  Protocol    ----  ----  --------    http  80    TCP查看service状态[root@node-1 demo]# kubectl describe services nginx-service Name:              nginx-serviceNamespace:         defaultLabels:            app=nginxAnnotations:       kubectl.kubernetes.io/last-applied-configuration:                     {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"nginx"},"name":"nginx-service","namespace":"default"},"s...Selector:          app=nginxType:              ClusterIPIP:                10.110.54.40Port:              http  80/TCPTargetPort:        80/TCPEndpoints:         10.244.2.22:80 #已和endpoints关联Session Affinity:  NoneEvents:            

8. 同理，如果此时容器的健康检查异常，kubelet会自动将其动endpoint中

删除站点信息，使健康检查异常[root@node-1 demo]# kubectl exec -it nginx-tcp-liveness-probe  /bin/bashroot@nginx-tcp-liveness-probe:/# rm -f /usr/share/nginx/html/test.html 查看pod健康检查event日志[root@node-1 demo]# kubectl get pods nginx-tcp-liveness-probe NAME                       READY   STATUS    RESTARTS   AGEnginx-tcp-liveness-probe   0/1     Running   0          11m[root@node-1 demo]# kubectl describe pods nginx-tcp-liveness-probe | tail                 node.kubernetes.io/unreachable:NoExecute for 300sEvents:  Type     Reason     Age                  From               Message  ----     ------     ----                 ----               -------  Normal   Scheduled  12m                  default-scheduler  Successfully assigned default/nginx-tcp-liveness-probe to node-3  Normal   Pulling    12m                  kubelet, node-3    Pulling image "nginx:latest"  Normal   Pulled     11m                  kubelet, node-3    Successfully pulled image "nginx:latest"  Normal   Created    11m                  kubelet, node-3    Created container nginx-tcp-liveness-probe  Normal   Started    11m                  kubelet, node-3    Started container nginx-tcp-liveness-probe  Warning  Unhealthy  119s (x32 over 11m)  kubelet, node-3    Readiness probe failed: HTTP probe failed with statuscode: 404查看endpoints[root@node-1 demo]# kubectl describe endpoints nginx-service Name:         nginx-serviceNamespace:    defaultLabels:       app=nginxAnnotations:  endpoints.kubernetes.io/last-change-trigger-time: 2019-09-30T14:38:01ZSubsets:  Addresses:            NotReadyAddresses:  10.244.2.22 #健康检查异常，此时加入到NotReady状态  Ports:    Name  Port  Protocol    ----  ----  --------    http  80    TCPEvents:  查看service状态，此时endpoints为空[root@node-1 demo]# kubectl describe services nginx-service Name:              nginx-serviceNamespace:         defaultLabels:            app=nginxAnnotations:       kubectl.kubernetes.io/last-applied-configuration:                     {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"nginx"},"name":"nginx-service","namespace":"default"},"s...Selector:          app=nginxType:              ClusterIPIP:                10.110.54.40Port:              http  80/TCPTargetPort:        80/TCPEndpoints:         #为空Session Affinity:  NoneEvents:            

1.6 TKE设置健康检查

TKE中可以设定应用的健康检查机制，健康检查机制包含在不同的Workload中，可以通过模板生成健康监测机制，定义过程中可以选择高级选项，默认健康检查机制是关闭状态，包含前面介绍的两种探针：存活探针livenessProbe和就绪探针readinessProbe，根据需要分别开启

开启探针之后进入设置健康检查，支持上述介绍的三种方法：执行命令检查、TCP端口检查，HTTP请求检查

选择不同的检查方法填写不同的参数即可，如启动间隔，检查间隔，响应超时，等参数，以HTTP请求检查方法为例：

设置完成后创建workload时候会自动生成yaml文件，以刚创建的deployment为例，生成健康检查yaml文件内容如下：

apiVersion: apps/v1beta2kind: Deploymentmetadata:  annotations:    deployment.kubernetes.io/revision: "1"    description: tke-health-check-demo  creationTimestamp: "2019-09-30T12:28:42Z"  generation: 1  labels:    k8s-app: tke-health-check-demo    qcloud-app: tke-health-check-demo  name: tke-health-check-demo  namespace: default  resourceVersion: "2060365354"  selfLink: /apis/apps/v1beta2/namespaces/default/deployments/tke-health-check-demo  uid: d6cf1f25-e37d-11e9-87fd-567eb17a3218spec:  minReadySeconds: 10  progressDeadlineSeconds: 600  replicas: 1  revisionHistoryLimit: 10  selector:    matchLabels:      k8s-app: tke-health-check-demo      qcloud-app: tke-health-check-demo  strategy:    rollingUpdate:      maxSurge: 1      maxUnavailable: 0    type: RollingUpdate  template:    metadata:      creationTimestamp: null      labels:        k8s-app: tke-health-check-demo        qcloud-app: tke-health-check-demo    spec:      containers:      - image: nginx:latest        imagePullPolicy: Always        livenessProbe:   #通过模板生成的健康检查机制          failureThreshold: 1          httpGet:            path: /            port: 80            scheme: HTTP          periodSeconds: 3          successThreshold: 1          timeoutSeconds: 2        name: tke-health-check-demo        resources:          limits:            cpu: 500m            memory: 1Gi          requests:            cpu: 250m            memory: 256Mi        securityContext:          privileged: false          procMount: Default        terminationMessagePath: /dev/termination-log        terminationMessagePolicy: File      dnsPolicy: ClusterFirst      imagePullSecrets:      - name: qcloudregistrykey      - name: tencenthubkey      restartPolicy: Always      schedulerName: default-scheduler      securityContext: {}      terminationGracePeriodSeconds: 30

写在最后

本章介绍kubernetes中健康检查两种Probe：livenessProbe和readinessProbe，livenessProbe主要用于存活检查，检查容器内部运行状态，readiness主要用于就绪检查，是否可以接受流量，通常需要和service的endpoints结合，当就绪准备妥当时加入到endpoints中，当就绪异常时从endpoints中删除，从而实现了services的健康检查和服务探测机制。对于Probe机制提供了三种检测的方法，分别适用于不同的场景：1. exec命令行，通过命令或shell实现健康检查，2. tcpSocket通过TCP协议探测端口，建立tcp连接，3. httpGet通过建立http请求探测，读者可多实操掌握其用法。

附录

健康检查：https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/

TKE健康检查设置方法：https://cloud.tencent.com/document/product/457/32815

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