Pod 生命周期二

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init 模板

init-example.yaml

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apiVersion: v1
kind: Pod
metadata:
  name: myapp-pod
  labels:
    app: myapp
spec:
  containers:
  - name: myapp-container
    image: busybox
    command: ['sh','-c','echo The app is running! && sleep 3600']
  initContainers:   # 关键字
  - name: init-myservice
    image: busybox
    command: ['sh','-c','until nslookup myservice; do echo waiting for myservice; sleep 2;done;']
  - name: init-mydb
    image: busybox
    command: ['sh','-c','until nslookup mydb; do echo waiting for mydb; sleep 2; done;']
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[root@k8s01 ~]# kubectl apply -f init-example.yaml
pod/myapp-pod created

[root@k8s01 ~]# kubectl get pods   # init 没成功
NAME        READY   STATUS     RESTARTS   AGE
myapp-pod   0/1     Init:0/2   0          13s

[root@k8s01 ~]# kubectl describe  pod myapp-pod
# 省略   

[root@k8s01 ~]# kubectl logs myapp-pod -c init-myservice

waiting for myservice
Server:         10.96.0.10
Address:        10.96.0.10:53

** server can't find myservice.default.svc.cluster.local: NXDOMAIN

*** Can't find myservice.svc.cluster.local: No answer
*** Can't find myservice.cluster.local: No answer
*** Can't find myservice.default.svc.cluster.local: No answer
*** Can't find myservice.svc.cluster.local: No answer
*** Can't find myservice.cluster.local: No answer

waiting for myservice
## init 未就绪

service-init-example.yaml

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kind: Service
apiVersion: v1
metadata:  
  name: myservice
spec:  
  ports:    
  - protocol: TCP      
    port: 80      
    targetPort: 9376
      
---
kind: Service
apiVersion: v1
metadata:  
  name: mydb
spec:  
  ports:    
  - protocol: TCP      
    port: 80      
    targetPort: 9377
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kubectl apply -f service-init-example.yaml

详细信息

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[root@k8s01 ~]# kubectl get pods  # 第一个 init 容器启动
NAME        READY   STATUS     RESTARTS   AGE
myapp-pod   0/1     Init:1/2   0          2m2s
[root@k8s01 ~]# kubectl get pods   # pod内容器启动
NAME        READY   STATUS            RESTARTS   AGE
myapp-pod   0/1     PodInitializing   0          2m44s
[root@k8s01 ~]# kubectl get pods
NAME        READY   STATUS    RESTARTS   AGE
myapp-pod   1/1     Running   0          2m49s
[root@k8s01 ~]# kubectl logs myapp-pod
The app is running!
[root@k8s01 ~]# kubectl describe pod myapp-pod
Name:         myapp-pod
Namespace:    default
Priority:     0
Node:         k8s02/192.168.43.102
Start Time:   Wed, 19 Aug 2020 09:05:25 -0400
Labels:       app=myapp
Annotations:  cni.projectcalico.org/podIP: 172.18.236.154/32
              cni.projectcalico.org/podIPs: 172.18.236.154/32
Status:       Running
IP:           172.18.236.154
IPs:
  IP:  172.18.236.154
Init Containers:
  init-myservice:
    Container ID:  docker://f1aac5b2b50ef5341ba949c72481cc739fbff046faa80113e388983ff438e92a
    Image:         busybox
    Image ID:      docker-pullable://busybox@sha256:4f47c01fa91355af2865ac10fef5bf6ec9c7f42ad2321377c21e844427972977
    Port:          <none>
    Host Port:     <none>
    Command:
      sh
      -c
      until nslookup myservice; do echo waiting for myservice; sleep 2;done;
    State:          Terminated
      Reason:       Completed
      Exit Code:    0
      Started:      Wed, 19 Aug 2020 09:05:43 -0400
      Finished:     Wed, 19 Aug 2020 09:06:58 -0400
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-rr77c (ro)
  init-mydb:
    Container ID:  docker://215168a8daf652ca35b5c3dc74705561d55dc4524c0ca98d6ec214ca3cf0a429
    Image:         busybox
    Image ID:      docker-pullable://busybox@sha256:4f47c01fa91355af2865ac10fef5bf6ec9c7f42ad2321377c21e844427972977
    Port:          <none>
    Host Port:     <none>
    Command:
      sh
      -c
      until nslookup mydb; do echo waiting for mydb; sleep 2; done;
    State:          Terminated
      Reason:       Completed
      Exit Code:    0
      Started:      Wed, 19 Aug 2020 09:07:21 -0400
      Finished:     Wed, 19 Aug 2020 09:07:47 -0400
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-rr77c (ro)
Containers:
  myapp-container:
    Container ID:  docker://76f2df54070bb74c813d45765f0440461a7c006ad85a122fdcb3b07c936b632c
    Image:         busybox
    Image ID:      docker-pullable://busybox@sha256:4f47c01fa91355af2865ac10fef5bf6ec9c7f42ad2321377c21e844427972977
    Port:          <none>
    Host Port:     <none>
    Command:
      sh
      -c
      echo The app is running! && sleep 3600
    State:          Running
      Started:      Wed, 19 Aug 2020 09:08:12 -0400
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-rr77c (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-rr77c:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-rr77c
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type    Reason     Age    From               Message
  ----    ------     ----   ----               -------
  Normal  Scheduled  2m59s  default-scheduler  Successfully assigned default/myapp-pod to k8s02
  Normal  Pulling    2m58s  kubelet, k8s02     Pulling image "busybox"
  Normal  Pulled     2m41s  kubelet, k8s02     Successfully pulled image "busybox"
  Normal  Created    2m41s  kubelet, k8s02     Created container init-myservice
  Normal  Started    2m41s  kubelet, k8s02     Started container init-myservice
  Normal  Pulling    86s    kubelet, k8s02     Pulling image "busybox"
  Normal  Pulled     63s    kubelet, k8s02     Successfully pulled image "busybox"
  Normal  Created    63s    kubelet, k8s02     Created container init-mydb
  Normal  Started    63s    kubelet, k8s02     Started container init-mydb
  Normal  Pulling    36s    kubelet, k8s02     Pulling image "busybox"
  Normal  Pulled     13s    kubelet, k8s02     Successfully pulled image "busybox"
  Normal  Created    13s    kubelet, k8s02     Created container myapp-container
  Normal  Started    12s    kubelet, k8s02     Started container myapp-container

检测探针 - 就绪检测

readinessProbe-http-get.yaml

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apiVersion: v1
kind: Pod
metadata:  
  name: readiness-httpget-pod  
  namespace: default
spec:  
  containers:  
  - name: readiness-httpget-container    
    image: nginx:1.7.9      
    imagePullPolicy: IfNotPresent    
    readinessProbe:      # 关键字
      httpGet:        
        port: 80        
        path: /index1.html      
      initialDelaySeconds: 1  # 触发延时
      periodSeconds: 3  # 重试间隔时间

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[root@k8s01 ~]#  kubectl  describe pod readiness-httpget-pod 
## 省略部分
Events:
  Type     Reason     Age   From               Message
  ----     ------     ----  ----               -------
  Normal   Scheduled  5s    default-scheduler  Successfully assigned default/readiness-httpget-pod to k8s03
  Normal   Pulled     4s    kubelet, k8s03     Container image "nginx:1.7.9" already present on machine
  Normal   Created    4s    kubelet, k8s03     Created container readiness-httpget-container
  Normal   Started    3s    kubelet, k8s03     Started container readiness-httpget-container
  Warning  Unhealthy  0s    kubelet, k8s03     Readiness probe failed: HTTP probe failed with statuscode: 404
## 探测失败

[root@k8s01 ~]# kubectl exec readiness-httpget-pod -it  -- /bin/bash
root@readiness-httpget-pod:/# echo "123" > /usr/share/nginx/html/index1.html
root@readiness-httpget-pod:/# exit
exit
[root@k8s01 ~]# kubectl  get pod
NAME                    READY   STATUS    RESTARTS   AGE
myapp-pod               1/1     Running   0          26m
readiness-httpget-pod   1/1     Running   0          3m34s

当有 index1.html 会返回 200 探测成功。日志省略

检测探针 - 存活检测

livenessProbe-exec.yaml

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apiVersion: v1
kind: Pod
metadata:  
  name: liveness-exec-pod 
  namespace: default
spec:  
  containers:  
  - name: liveness-exec-container   
    image: busybox:1.32.0   
    imagePullPolicy: IfNotPresent    
    command: ["/bin/sh","-c","touch /tmp/live ; sleep 60; rm -rf /tmp/live; sleep 3600"]      
    livenessProbe:      
      exec:        
        command: ["test","-e","/tmp/live"]      
      initialDelaySeconds: 1      
      periodSeconds: 3

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[root@k8s01 ~]# kubectl get pod  ## liveness-exec-pod  会 周期性 restart 
NAME                    READY   STATUS             RESTARTS   AGE
liveness-exec-pod       0/1     CrashLoopBackOff   6          10m
myapp-pod               1/1     Running            0          7h31m
readiness-httpget-pod   1/1     Running            0          7h1m

livenessProbe-httpget

livenessProbe-httpget.yaml

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apiVersion: v1
kind: Pod
metadata:  
  name: liveness-httpget-pod  
  namespace: default
spec:
  containers:  
  - name: liveness-httpget-container    
    image: nginx:1.7.9  
    imagePullPolicy: IfNotPresent    
    ports:    
    - name: http      
      containerPort: 80    
    livenessProbe:      
      httpGet:        
        port: 80        
        path: /index.html      
      initialDelaySeconds: 1      
      periodSeconds: 3      
      timeoutSeconds: 10

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[root@k8s01 ~]# kubectl exec liveness-httpget-pod -it -- /bin/bash
## 修改 /index.html 为 index1.html

[root@k8s01 ~]# kubectl get pod  ## liveness-httpget-pod 会 restart 
NAME                    READY   STATUS             RESTARTS   AGE
liveness-exec-pod       0/1     CrashLoopBackOff   6          12m
liveness-httpget-pod    1/1     Running            1          2m59s
myapp-pod               1/1     Running            0          7h31m
readiness-httpget-pod   1/1     Running            0          7h1m

livenessProbe-tcp

livenessProbe-tcp.yaml

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apiVersion: v1
kind: Pod
metadata:
  name: probe-tcp
spec:
  containers:
  - name: nginx
    image: nginx：1.7.9 
    livenessProbe:      
      initialDelaySeconds: 5      
      timeoutSeconds: 1      
      tcpSocket:        
        port: 80  
      periodSeconds: 3

livenessProbe-tcp-81.yaml 

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apiVersion: v1
kind: Pod
metadata:
  name: probe-tcp1
spec:
  containers:
  - name: nginx
    image: nginx：1.7.9 
    livenessProbe:      
      initialDelaySeconds: 5      
      timeoutSeconds: 1      
      tcpSocket:        
        port: 81 
      periodSeconds: 3
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[root@k8s01 ~]# kubectl get pod # tcp 80 端口可以检测到，81端口一直重启
NAME          READY   STATUS             RESTARTS   AGE
probe-tcp80   1/1     Running            0          19s
probe-tcp81   0/1     CrashLoopBackOff   4          2m48s


[root@k8s01 ~]# kubectl get pod
NAME          READY   STATUS    RESTARTS   AGE
probe-tcp80   1/1     Running   0          74s
probe-tcp81   1/1     Running   6          3m43s

查看日志

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# 节选 ， Liveness probe failed: dial tcp 172.18.235.163:81: connect: connection refused
Events:
  Type     Reason     Age                     From               Message
  ----     ------     ----                    ----               -------
  Normal   Scheduled  <unknown>               default-scheduler  Successfully assigned default/probe-tcp81 to k8s03
  Normal   Created    6h39m (x4 over 6h41m)   kubelet, k8s03     Created container nginx
  Normal   Started    6h39m (x4 over 6h41m)   kubelet, k8s03     Started container nginx
  Normal   Killing    6h39m (x3 over 6h40m)   kubelet, k8s03     Container nginx failed liveness probe, will be restarted
  Normal   Pulled     6h39m (x4 over 6h41m)   kubelet, k8s03     Container image "nginx:1.7.9" already present on machine
  Warning  Unhealthy  6h39m (x10 over 6h41m)  kubelet, k8s03     Liveness probe failed: dial tcp 172.18.235.163:81: connect: connection refused
  Warning  BackOff    6h36m (x10 over 6h38m)  kubelet, k8s03     Back-off restarting failed container

删除所有 pod

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kubectl delete pod --all

存活+就绪 检测 + startup 检测（1.16 版本）

liveness-readiness.yaml

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apiVersion: v1
kind: Pod
metadata:  
  name: liveness-readiness-pod  
  namespace: default
spec:  
  containers:  
  - name: liveness-readiness-container    
    image: nginx:1.7.9      
    imagePullPolicy: IfNotPresent    
    readinessProbe:      # 关键字
      httpGet:        
        port: 80        
        path: /index1.html      
      initialDelaySeconds: 1  # 触发延时
      periodSeconds: 3  # 重试间隔时间
    livenessProbe:      
      httpGet:        
        port: http        
        path: /index.html      
      initialDelaySeconds: 1      
      periodSeconds: 3      
      timeoutSeconds: 10
    startupProbe:    #   最先进行 startupProbe,3次没通过就重启，通过后 进行 另外两个检测
      httpGet:
        path: /index.html
        port: 80
      failureThreshold: 3   #失败阈值
      periodSeconds: 2

一旦容器通过了 startupProbe 后，Kubelet 会每隔 3(定义的时间) 秒钟进行一次探活检测 （livenessProbe），每隔 10(定义的时间) 秒进行一次就绪检测（readinessProbe）。

启动、退出动作

start_stop.yaml

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apiVersion: v1
kind: Pod
metadata:  
  name: lifecycle-demo
spec:
  containers:
  - name: lifecycle-demo-container    
    image: nginx    
    lifecycle:      
      postStart:   # 启动动作     
        exec:          
          command: ["/bin/sh", "-c", "echo Hello from the postStart handler >/usr/share/message"]      
      preStop:     # 退出动作   
        exec:
          command: ["/bin/sh", "-c", "echo Hello from the poststop handler >/usr/share/message"]

查看显示

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[root@k8s01 ~]# kubectl exec lifecycle-demo -it -- /bin/bash 

root@lifecycle-demo:/# cat /usr/share/message
Hello from the postStart handler  # start 成功