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kongshuo

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Kubernetes Pod管理及重启策略

Pod创建

# 创建命名空间
> 这里的kubens命令是我自行设置简短的，想设置的可以参考我的博客：https://www.cnblogs.com/kongshuo/p/17412322.html
# 创建
[root@kmaster ~]# kubectl create ns kongshuo
namespace/kongshuo created
[root@kmaster ~]# kubens 
calico-apiserver
calico-system
default
kongshuo
kube-node-lease
kube-public
kube-system
tigera-operator
# 切换至创建的命名空间
[root@kmaster ~]# kubens kongshuo
Context "kubernetes-admin@kubernetes" modified.
Active namespace is "kongshuo".
[root@kmaster ~]# kubens 
calico-apiserver
calico-system
default
kongshuo
kube-node-lease
kube-public
kube-system
tigera-operator

# 创建一个简单的nginx
[root@kmaster ~]# kubectl get pod
No resources found in kongshuo namespace.
[root@kmaster ~]# kubectl run pod1 --image nginx
pod/pod1 created
[root@kmaster ~]# kubectl get pod
NAME   READY   STATUS    RESTARTS   AGE
pod1   1/1     Running   0          24s

# 查看pod运行在哪个节点
[root@kmaster ~]# kubectl get pod -o wide
NAME   READY   STATUS    RESTARTS   AGE   IP              NODE     NOMINATED NODE   READINESS GATES
pod1   1/1     Running   0          95s   10.244.69.201   knode2   <none>           <none>

# 查看节点是否下载了nginx镜像
[root@knode2 ~]# crictl img
IMAGE                                                TAG                 IMAGE ID            SIZE
docker.io/calico/cni                                 v3.25.0             d70a5947d57e5       88MB
docker.io/calico/csi                                 v3.25.0             f37eacbb9a295       9.08MB
docker.io/calico/kube-controllers                    v3.25.0             5e785d005ccc1       31.3MB
docker.io/calico/node-driver-registrar               v3.25.0             c14671fdda128       11.1MB
docker.io/calico/node                                v3.25.0             08616d26b8e74       87.2MB
docker.io/calico/pod2daemon-flexvol                  v3.25.0             ed8b7bbb113fe       7.08MB
docker.io/calico/typha                               v3.25.0             7b60c7012b1c9       28.5MB
docker.io/library/nginx                              latest              448a08f1d2f94       57MB
quay.io/tigera/operator                              v1.29.0             343ea4f89a32c       21.1MB
registry.aliyuncs.com/google_containers/coredns      v1.9.3              5185b96f0becf       14.8MB
registry.aliyuncs.com/google_containers/kube-proxy   v1.26.0             556768f31eb1d       21.5MB
registry.aliyuncs.com/google_containers/pause        3.6                 6270bb605e12e       302kB

# 查看pod详细信息
[root@kmaster ~]# kubectl describe pod pod1 
Name:             pod1
Namespace:        kongshuo
Priority:         0
Service Account:  default
Node:             knode2/192.168.100.182
Start Time:       Fri, 19 May 2023 12:03:29 +0800
Labels:           run=pod1
Annotations:      cni.projectcalico.org/containerID: 1e53a3fe0b3b6f7d8983709d51ace6114c3f057dc5d43bf8ef1c730234ae7675
                  cni.projectcalico.org/podIP: 10.244.69.202/32
                  cni.projectcalico.org/podIPs: 10.244.69.202/32
Status:           Running
IP:               10.244.69.202
IPs:
  IP:  10.244.69.202
Containers:
  pod1:
    Container ID:   containerd://8d3910112bd21740735b125656e3b6cd8f88e890794c719a3cd9c441adab75fe
    Image:          nginx
    Image ID:       docker.io/library/nginx@sha256:480868e8c8c797794257e2abd88d0f9a8809b2fe956cbfbc05dcc0bca1f7cd43
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Mon, 22 May 2023 09:20:54 +0800
    Last State:     Terminated
      Reason:       Unknown
      Exit Code:    255
      Started:      Fri, 19 May 2023 12:03:41 +0800
      Finished:     Mon, 22 May 2023 09:19:39 +0800
    Ready:          True
    Restart Count:  1
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-q62zp (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  kube-api-access-q62zp:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
QoS Class:                   BestEffort
Node-Selectors:              <none>
Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type    Reason          Age                    From               Message
  ----    ------          ----                   ----               -------
  Normal  Scheduled       2d21h                  default-scheduler  Successfully assigned kongshuo/pod1 to knode2
  Normal  Pulling         2d21h                  kubelet            Pulling image "nginx"
  Normal  Pulled          2d21h                  kubelet            Successfully pulled image "nginx" in 11.222394648s (11.222400274s including waiting)
  Normal  Created         2d21h                  kubelet            Created container pod1
  Normal  Started         2d21h                  kubelet            Started container pod1
  Normal  SandboxChanged  3m26s (x3 over 4m23s)  kubelet            Pod sandbox changed, it will be killed and re-created.
  Normal  Pulling         3m25s                  kubelet            Pulling image "nginx"
  Normal  Pulled          3m23s                  kubelet            Successfully pulled image "nginx" in 2.40067693s (2.400682318s including waiting)
  Normal  Created         3m23s                  kubelet            Created container pod1
  Normal  Started         3m22s                  kubelet            Started container pod1

镜像下载策略

# Always:每次下载都会联网检查镜像，不管是否下载于本地，都会有联网检查
# Never:只会使用本地镜像，不会联网下载
# IfNotPresent：如果检测本地没有所需镜像，才会联网下载

# 不使用--image-pull-policy参数默认使用Always
[root@kmaster ~]# kubectl run pod2 --image nginx
pod/pod2 created
[root@kmaster ~]# kubectl get pod -o wide
NAME   READY   STATUS    RESTARTS      AGE     IP               NODE     NOMINATED NODE   READINESS GATES
pod1   1/1     Running   1 (99m ago)   2d22h   10.244.69.202    knode2   <none>           <none>
pod2   1/1     Running   0             89m     10.244.195.145   knode1   <none>           <none>

# 使用Never本地有nginx镜像直接创建
[root@kmaster ~]# kubectl run pod3 --image nginx --image-pull-policy Never
pod/pod3 created
[root@kmaster ~]# kubectl get pod -o wide
NAME   READY   STATUS    RESTARTS      AGE     IP               NODE     NOMINATED NODE   READINESS GATES
pod1   1/1     Running   1 (99m ago)   2d22h   10.244.69.202    knode2   <none>           <none>
pod2   1/1     Running   0             89m     10.244.195.145   knode1   <none>           <none>
pod3   1/1     Running   0             10s     10.244.69.207    knode2   <none>           <none>

# 使用IfNotPresent本地有nginx镜像直接创建
[root@kmaster ~]# kubectl run pod4 --image nginx --image-pull-policy IfNotPresent
pod/pod4 created
[root@kmaster ~]# kubectl get pod -o wide
NAME   READY   STATUS    RESTARTS       AGE     IP               NODE     NOMINATED NODE   READINESS GATES
pod1   1/1     Running   1 (101m ago)   2d22h   10.244.69.202    knode2   <none>           <none>
pod2   1/1     Running   0              91m     10.244.195.145   knode1   <none>           <none>
pod3   1/1     Running   0              2m43s   10.244.69.207    knode2   <none>           <none>
pod4   1/1     Running   0              8s      10.244.195.146   knode1   <none>           <none>

Pod删除

# 删除Pod（两种方法均可）
[root@kmaster ~]# kubectl delete pods/pod1
pod "pod1" deleted
[root@kmaster ~]# kubectl delete pod pod2
pod "pod2" deleted
[root@kmaster ~]# kubectl delete pods/pod3
pod "pod3" deleted
[root@kmaster ~]# kubectl delete pod pod4
pod "pod4" deleted

Pod测试演练

# 服务端测试
[root@kmaster ~]# kubectl run pod1 --image nginx --image-pull-policy IfNotPresent --dry-run=server
pod/pod1 created (server dry run)
[root@kmaster ~]# kubectl get pod
No resources found in kongshuo namespace.

# 客户端测试（yaml输出建议输出客户端，不建议输出服务端）
[root@kmaster ~]# kubectl run pod1 --image nginx --image-pull-policy IfNotPresent --dry-run=client
pod/pod1 created (dry run)
[root@kmaster ~]# kubectl get pod
No resources found in kongshuo namespace.
[root@kmaster ~]# kubectl run pod1 --image nginx --image-pull-policy IfNotPresent --dry-run=client -o yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: pod1
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

使用yaml创建Pod

# 保存yaml
# --sleep 3600使/bin/bash持续运行
[root@kmaster ~]# mkdir pod_yaml
[root@kmaster ~]# kubectl run pod1 --image nginx --image-pull-policy IfNotPresent --dry-run=client -o yaml -- sleep 3600 > /root/pod_yaml/pod1.yaml
[root@kmaster ~]# cd pod_yaml/
[root@kmaster pod_yaml]# ls
pod1.yaml
[root@kmaster pod_yaml]# cat pod1.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - args:
    - sleep
    - "3600"
    image: nginx
    imagePullPolicy: IfNotPresent
    name: pod1
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
[root@kmaster pod_yaml]# kubectl apply -f pod1.yaml 
pod/pod1 configured
[root@kmaster pod_yaml]# kubectl get pod -o wide 
NAME   READY   STATUS    RESTARTS   AGE   IP              NODE     NOMINATED NODE   READINESS GATES
pod1   1/1     Running   0          55s   10.244.69.209   knode2   <none>           <none>

进入Pod

[root@kmaster ~]# kubectl get pod
NAME   READY   STATUS    RESTARTS   AGE
pod1   1/1     Running   0          10m
[root@kmaster ~]# kubectl exec -it pods/pod1 -- bash
root@pod1:/# ls
bin   dev		   docker-entrypoint.sh  home  lib64  mnt  proc  run   srv  tmp  var
boot  docker-entrypoint.d  etc			 lib   media  opt  root  sbin  sys  usr

Pod创建两个容器

[root@kmaster pod_yaml]# ls
pod1.yaml
[root@kmaster pod_yaml]# cp pod1.yaml pod2.yaml
[root@kmaster pod_yaml]# vim pod2.yaml 
[root@kmaster pod_yaml]# cat pod2.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: podkongshuo
  name: podkongshuo
spec:
  containers:
  - args:
    - sleep
    - "3600"
    image: centos
    imagePullPolicy: IfNotPresent
    name: pod11
    resources: {}
  - args:
    - sleep
    - "3600"
    image: centos
    imagePullPolicy: IfNotPresent
    name: pod22
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
[root@kmaster pod_yaml]# kubectl apply -f pod2.yaml 
pod/podkongshuo created
[root@kmaster pod_yaml]# kubectl get pod -o wide 
NAME          READY   STATUS    RESTARTS   AGE   IP               NODE     NOMINATED NODE   READINESS GATES
pod1          1/1     Running   0          22m   10.244.69.209    knode2   <none>           <none>
podkongshuo   2/2     Running   0          28s   10.244.195.148   knode1   <none>           <none>

# 进入容器pod11
[root@kmaster ~]# kubectl exec -it pods/podkongshuo -c pod11 -- bash
[root@podkongshuo /]# ls
bin  dev  etc  home  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
# 进入容器pod22
[root@kmaster ~]# kubectl exec -it pods/podkongshuo -c pod22 -- bash
[root@podkongshuo /]# ls
bin  dev  etc  home  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var

Pod重启策略

# Always：非正常退出一直重启
# Never： 无论正常还是非正常，从不重启
# OnFailure： 遇到错误重启

# Always比如定义错了命令，这时候创建该pod，并观察错误过程，会发现它在不断尝试重启
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - args:
    - sleeeep
    - "3600"
    image: nginx
    imagePullPolicy: IfNotPresent
    name: pod1
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
[root@kmaster ~]# kubectl get pod -o wide
NAME   READY   STATUS             RESTARTS      AGE    IP               NODE     NOMINATED NODE   READINESS GATES
pod1   0/1     CrashLoopBackOff   4 (24s ago)   107s   10.244.69.144    knode2   <none>           <none>

# Never重来不重启
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - args:
    - sleeeep
    - "3600"
    image: nginx
    imagePullPolicy: IfNotPresent
    name: pod1
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Never
status: {}
[root@kmaster ~]# kubectl get pod -o wide
NAME   READY   STATUS   RESTARTS     AGE    IP              NODE    NOMINATED NODE   READINESS GATES
pod1   0/1      Error   0            47s   10.244.69.145    knode2   <none>          <none>

# OnFailure遇到（命令）错误才会重启，正常退出是不会重启的
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - args:
    - sleeeep
    - "3600"
    image: nginx
    imagePullPolicy: IfNotPresent
    name: pod1
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: OnFailure
status: {}
[root@kmaster ~]# kubectl get pod -o wide
NAME   READY   STATUS     RESTARTS      AGE    IP               NODE     NOMINATED NODE   READINESS GATES
pod1   0/1     Error      4 (35s ago)   59s    10.244.69.146    knode2   <none>           <none>


# onfailure如果是正常退出，没有遇到错误，不会重启
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - args:
    - sleep
    - "3600"
    image: nginx
    imagePullPolicy: IfNotPresent
    name: pod1
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: OnFailure
status: {}
[root@kmaster ~]# kubectl get pod -o wide
NAME   READY   STATUS     RESTARTS      AGE    IP               NODE     NOMINATED NODE   READINESS GATES
pod1   0/1     Completed  0             46s    10.244.69.147    knode2   <none>           <none>

本文作者：kongshuo

本文链接：https://www.cnblogs.com/kongshuo/p/17414768.html

版权声明：本作品采用知识共享署名-非商业性使用-禁止演绎 2.5 中国大陆许可协议进行许可。

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