节点基于资源压力要驱逐pod时，pod的状态是什么？

当pod的所在的主机出现资源压力的时候，比如我们模拟了一个磁盘使用率超过90%的场景

在pod正常运行时，pod的状态是Running

[root@nccztsjb-node-23 ~]# kubectl get pod
NAME                        READY   STATUS    RESTARTS   AGE
nginx-ds-lw4vj              1/1     Running   0          6d19h
nginx-ds-nrf4t              1/1     Running   0          6d19h
nginx-ds-ql4s8              1/1     Running   0          6d19h
nginx-test-56745657-6wj5n   1/1     Running   0          6d19h
nginx-test-56745657-jx2kp   1/1     Running   0          6d19h
nginx-test-56745657-m6hm4   1/1     Running   0          6d19h
nginx-test-56745657-mhjsh   1/1     Running   0          6d19h
nginx-test-56745657-pqhqp   1/1     Running   0          6d19h

[root@nccztsjb-node-23 ~]# kubectl get pod nginx-test-56745657-6wj5n -o yaml | grep phase
  phase: Running

即phase为: Running

然后，通过fallocate模拟一个190G的大文件

fallocate -l 190G bigfile

磁盘空间使用率涨到96%

[root@nccztsjb-node-24 data]# df -h /data
Filesystem      Size  Used Avail Use% Mounted on
/dev/vdb        200G  191G  9.2G  96% /data
[root@nccztsjb-node-24 data]# 

pod被驱逐，查看pod的状态或者说阶段

[root@nccztsjb-node-23 ~]# kubectl get pod nginx-test-56745657-6wj5n -o yaml | grep -i phase
  phase: Failed
[root@nccztsjb-node-23 ~]#

已经变为：Failed

查看pod的描述信息

[root@nccztsjb-node-23 ~]# kubectl describe pod nginx-test-56745657-6wj5n
Name:           nginx-test-56745657-6wj5n
Namespace:      default
Priority:       0
Node:           nccztsjb-node-24/172.20.58.65
Start Time:     Thu, 17 Mar 2022 15:13:17 +0800
Labels:         app=nginx-test
                pod-template-hash=56745657
Annotations:    cni.projectcalico.org/containerID: cbd9967186479712f1e7c27112fc9b9a31e5628d21e2ec7e96c2a4c8a8a956ea
                cni.projectcalico.org/podIP: 
                cni.projectcalico.org/podIPs: 
Status:         Failed
Reason:         Evicted
Message:        The node was low on resource: ephemeral-storage. Container nginx was using 24Ki, which exceeds its request of 0. 
IP:             
IPs:            <none>
Controlled By:  ReplicaSet/nginx-test-56745657
Containers:
  nginx:
    Container ID:   
    Image:          172.20.58.152/middleware/nginx:1.21.4
    Image ID:       
    Port:           <none>
    Host Port:      <none>
    State:          Terminated
      Reason:       ContainerStatusUnknown
      Message:      The container could not be located when the pod was terminated
      Exit Code:    137
      Started:      Mon, 01 Jan 0001 00:00:00 +0000
      Finished:     Mon, 01 Jan 0001 00:00:00 +0000
    Last State:     Terminated
      Reason:       ContainerStatusUnknown
      Message:      The container could not be located when the pod was deleted.  The container used to be Running
      Exit Code:    137
      Started:      Mon, 01 Jan 0001 00:00:00 +0000
      Finished:     Mon, 01 Jan 0001 00:00:00 +0000
    Ready:          False
    Restart Count:  1
    Limits:
      cpu:     500m
      memory:  200Mi
    Requests:
      cpu:        500m
      memory:     200Mi
    Environment:  <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-cmp26 (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             False 
  ContainersReady   False 
  PodScheduled      True 
Volumes:
  kube-api-access-cmp26:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
QoS Class:                   Guaranteed
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
  ----     ------   ----  ----     -------
  Warning  Evicted  82s   kubelet  The node was low on resource: ephemeral-storage. Container nginx was using 24Ki, which exceeds its request of 0.
  Normal   Killing  82s   kubelet  Stopping container nginx

可以看出，由于节点存在临时存储压力，所以，kubelet将停止nginx容器。

简单来说，磁盘压力是kubelet发出来的，停止的操作也是有kubelet发起的。