【kubernetes系列学习】如何使pod和host主机的时间保持一致？

【kubernetes系列学习】如何使pod和host主机的时间保持一致？

问题及主要目的

pod内输出的当前date与host主机上输出的date是不一致的，这样有时候看pod的日志会有迷惑性，下面来解决一下~

实验环境信息

[root@ningan ~]# uname -a
Linux ningan 5.4.0-131-generic #147~18.04.1-Ubuntu SMP Sat Oct 15 13:10:18 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

在Ubuntu上，/etc/localtime是系统的本地时区设置文件，影响到系统的当前date输出。
Ubuntu 18.04上，/etc/localtime是一个symbolic link，链接到文件：/usr/share/zoneinfo/Asia/Shanghai
/usr/share/zoneinfo下存储着真正的时区设置文件，/usr/share/zoneinfo/Asia/Shanghai也是一个符号链接，指向的是/usr/share/zoneinfo/PRC

[root@ningan ~]# ls -l /etc/localtime
lrwxrwxrwx 1 root root 33 Sep 24 10:18 /etc/localtime -> /usr/share/zoneinfo/Asia/Shanghai
[root@ningan ~]#
[root@ningan ~]# ls -l /usr/share/zoneinfo/Asia/Shanghai
lrwxrwxrwx 1 root root 6 Aug 30 16:20 /usr/share/zoneinfo/Asia/Shanghai -> ../PRC
[root@ningan ~]#
[root@ningan ~]# ls -l /usr/share/zoneinfo/PRC
-rw-r--r-- 1 root root 582 Aug 30 16:20 /usr/share/zoneinfo/PRC

[root@ningan ~]# file /etc/localtime
/etc/localtime: symbolic link to /usr/share/zoneinfo/Asia/Shanghai

[root@ningan ~]# file /usr/share/zoneinfo/Asia/Shanghai
/usr/share/zoneinfo/Asia/Shanghai: symbolic link to ../PRC

[root@ningan ~]# file /usr/share/zoneinfo/PRC
/usr/share/zoneinfo/PRC: timezone data, version 2, 3 gmt time flags, 3 std time flags, no leap seconds, 29 transition times, 3 abbreviation chars

实验1：正常创建pod，pod和host的时间不一致

[root@ningan ~]# cat nginx.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        imagePullPolicy: Always
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  ports:
  - port: 9000
    name: nginx-svc
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx

### 下发yaml，创建pod
[root@ningan ~]# kubectl apply -f nginx.yaml
deployment.apps/nginx-deployment created

### 查看启动的pod和svc
[root@ningan ~]# kubectl get pod,svc -A |grep nginx
default                pod/nginx-deployment-68d5f6d6b7-4rhj4            1/1     Running            0                20s
default                pod/nginx-deployment-68d5f6d6b7-5dm2f            1/1     Running            0                20s
default                pod/nginx-deployment-68d5f6d6b7-mvhpg            1/1     Running            0                20s
default                service/nginx                       ClusterIP   11.254.209.126   <none>        9000/TCP                       20s

### 进入到容器中，查看容器的当前时间
[root@ningan ~]# kubectl exec -it nginx-deployment-68d5f6d6b7-4rhj4 -- sh
# uname -a
Linux nginx-deployment-68d5f6d6b7-4rhj4 5.4.0-131-generic #147~18.04.1-Ubuntu SMP Sat Oct 15 13:10:18 UTC 2022 x86_64 GNU/Linux
# ls -l /etc/localtime
lrwxrwxrwx 1 root root 27 Mar 26  2019 /etc/localtime -> /usr/share/zoneinfo/Etc/UTC
# date
Fri Oct 28 15:37:43 UTC 2022
# exit

### 到主机上，查看主机的当前时间
[root@ningan ~]# date
Fri Oct 28 23:37:49 CST 2022

可以看到，pod内的时间和host主机的时间是相差了8个小时的。

实验2：挂载主机的/usr/share/zoneinfo/Asia/Shanghai

修改pod的yaml文件，挂载主机的/usr/share/zoneinfo/Asia/Shanghai到pod的/etc/localtime，保证pod和host的时间一致

[root@ningan ~]# cat nginx-date-test.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        imagePullPolicy: Always
        ports:
        - containerPort: 80
        volumeMounts:
        - name: tz-config
          mountPath: /etc/localtime
      volumes:
      - name: tz-config
        hostPath:
          path: /usr/share/zoneinfo/Asia/Shanghai
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  ports:
  - port: 9000
    name: nginx-svc
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx

在之前的yaml里新加了挂载文件，如下：

### 重新下发yaml
[root@ningan ~]# kubectl apply -f nginx-date-test.yaml
deployment.apps/nginx-deployment configured
service/nginx unchanged

### 查看启动的pod和svc
[root@ningan ~]# kubectl get pod,svc -owide -A |grep nginx
default                pod/nginx-deployment-ff5879d6b-lxb5h             1/1     Running            0                3m55s   192.169.219.76   master   <none>           <none>
default                pod/nginx-deployment-ff5879d6b-tr2h6             1/1     Running            0                3m59s   192.169.219.75   master   <none>           <none>
default                pod/nginx-deployment-ff5879d6b-zjmzf             1/1     Running            0                4m4s    192.169.219.74   master   <none>           <none>
default                service/nginx                       ClusterIP   11.254.209.126   <none>        9000/TCP                       28m     app=nginx

### 进入到容器中，查看容器的当前时间
[root@ningan ~]# kubectl exec -it nginx-deployment-ff5879d6b-lxb5h -- date
Sat Oct 29 00:03:02 CST 2022

### 到主机上，查看主机的当前时间
[root@ningan ~]# date
Sat Oct 29 00:03:08 CST 2022

已经修改成功，大功告成！

实验3：挂载主机的/etc/localtime

修改pod的yaml文件，挂载主机的/etc/localtime到pod的/etc/localtime，保证pod和host的时间一致

[root@ningan addons]# cat nginx-date-test2.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        imagePullPolicy: Always
        ports:
        - containerPort: 80
        volumeMounts:
        - name: tz-config
          mountPath: /etc/localtime
      volumes:
      - name: tz-config
        hostPath:
          path: /etc/localtime
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  ports:
  - port: 9000
    name: nginx-svc
    protocol: TCP
    targetPort: 80
  selector:
    app: nginx

在实验1的yaml里新加了挂载文件，如下：

在实验2的yaml里修改了挂载文件，如下：

### 删除之前pod
[root@ningan addons]# kubectl delete -f nginx-date-test.yaml
deployment.apps "nginx-deployment" deleted
service "nginx" deleted

[root@ningan addons]# kubectl get pod,svc -owide -A |grep nginx
[root@ningan addons]#

### 下发新的yaml
[root@ningan addons]# kubectl get pod,svc -owide -A |grep nginx
default                pod/nginx-deployment-b85dc87bc-6zds7             1/1     Running   0                54s     192.169.219.77   master   <none>           <none>
default                pod/nginx-deployment-b85dc87bc-httb5             1/1     Running   0                54s     192.169.219.79   master   <none>           <none>
default                pod/nginx-deployment-b85dc87bc-n4rfm             1/1     Running   0                54s     192.169.219.78   master   <none>           <none>
default                service/nginx                       ClusterIP   11.254.240.43   <none>        9000/TCP                       54s     app=nginx

### 进入到容器中，查看容器的当前时间
[root@ningan addons]# kubectl exec -it nginx-deployment-b85dc87bc-6zds7 -- date
Sat Oct 29 00:15:08 CST 2022

### 到主机上，查看主机的当前时间
[root@ningan addons]# date
Sat Oct 29 00:15:10 CST 2022

大功告成~

参考

Kubernetes集群Pod使用Host的本地时区设置