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关于 Kubernetes中Pod的一些笔记（一）

山河已无恙发表于 2021/11/25 23:23:04 2021/11/25

【摘要】钱比你想象的重要得多，超过20岁了就别整天活在梦里了，对于平凡的你来讲，钱就是你的尊严。

写在前面

学习K8s，刚把Pod学完，整理笔记记忆
笔记主要是Pod的一些基本操作,偏实战,理论很少：
笔记内容包括:
- 创建Pod的两种方式，相关镜像下载，重启机制
- Pod的详细信息，日志、命令运行等、生命周期等
- 初始化Pod和静态Pod
- Pod的调度(选择器、指定节点、主机亲和性)
- 节点的coedon与drain
- 节点的taint(污点)及容忍污点(tolerations)
- 部分地方使用了ansible，但是不影响阅读

钱比你想象的重要得多，超过20岁了就别整天活在梦里了，对于平凡的你来讲，钱就是你的尊严。

Pod 学习环境测试

ansible ping测试

┌──[root@vms81.liruilongs.github.io]-[~]
└─$cd ansible/
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible node -m ping
192.168.26.82 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python"
    },
    "changed": false,
    "ping": "pong"
}
192.168.26.83 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python"
    },
    "changed": false,
    "ping": "pong"
}

docker环境测试

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible 192.168.26.83 -m shell -a "systemctl enable docker --now"
192.168.26.83 | CHANGED | rc=0 >>
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl get nodes
NAME                         STATUS   ROLES                  AGE     VERSION
vms81.liruilongs.github.io   Ready    control-plane,master   7d23h   v1.21.1
vms82.liruilongs.github.io   Ready    <none>                 7d23h   v1.21.1
vms83.liruilongs.github.io   Ready    <none>                 7d23h   v1.21.1
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$

一、帮助文档的使用

kubectl explain --help

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl explain --help

查看pod的语法结构

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl explain pods
KIND:     Pod
VERSION:  v1
DESCRIPTION:
     Pod is a collection of containers that can run on a host. This resource is
     created by clients and scheduled onto hosts.
FIELDS:
   apiVersion   <string>
  ....
   kind <string>
  .....
   metadata     <Object>
  .....
   spec <Object>
  .....
   status       <Object>
  ....
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl explain pods.metadata
KIND:     Pod
VERSION:  v1

二、创建Pod的方式

这里因为是学习，所以我们新建一个命名空间用于学习

新建命名空间:

kubectl config set-context context1 --namespace=liruilong-pod-create

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$mkdir k8s-pod-create
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$cd k8s-pod-create/
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl create ns liruilong-pod-create
namespace/liruilong-pod-create created

查看当前集群信息

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: https://192.168.26.81:6443
  name: cluster1
contexts:
- context:
    cluster: cluster1
    namespace: kube-system
    user: kubernetes-admin1
  name: context1
current-context: context1
kind: Config
preferences: {}
users:
- name: kubernetes-admin1
  user:
    client-certificate-data: REDACTED
    client-key-data: REDACTED

查看命名空间

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get  ns
NAME                   STATUS   AGE
default                Active   8d
kube-node-lease        Active   8d
kube-public            Active   8d
kube-system            Active   8d
liruilong              Active   7d10h
liruilong-pod-create   Active   4m18s

设置刚才新建的命名空间为当前命名空间

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl config set-context context1 --namespace=liruilong-pod-create
Context "context1" modified.
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$docker pull nginx
Using default tag: latest
latest: Pulling from library/nginx
b380bbd43752: Pull complete
fca7e12d1754: Pull complete
745ab57616cb: Pull complete
a4723e260b6f: Pull complete
1c84ebdff681: Pull complete
858292fd2e56: Pull complete
Digest: sha256:644a70516a26004c97d0d85c7fe1d0c3a67ea8ab7ddf4aff193d9f301670cf36
Status: Downloaded newer image for nginx:latest
docker.io/library/nginx:latest

命令行的方式创建pod

kubectl run podcommon --image=nginx --image-pull-policy=IfNotPresent --labels="name=liruilong" --env="name=liruilong"

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl run podcommon --image=nginx --image-pull-policy=IfNotPresent --labels="name=liruilong" --env="name=liruilong"
pod/podcommon created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods
NAME        READY   STATUS              RESTARTS   AGE
podcommon   0/1     ContainerCreating   0          12s

查看pod调度到了那个节点

kubectl get pods -o wide

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl run pod-demo --image=nginx  --labels=name=nginx --env="user=liruilong" --port=8888  --image-pull-policy=IfNotPresent
pod/pod-demo created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl  get pods -o wide
NAME          READY   STATUS    RESTARTS   AGE     IP               NODE                         NOMINATED NODE   READINESS GATES
pod-demo      1/1     Running   0          94s     10.244.171.149   vms82.liruilongs.github.io   <none>           <none>
poddemo       1/1     Running   0          8m22s   10.244.70.41     vms83.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$

删除pod

kubectl delete pod pod-demo --force

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl delete pod pod-demo --force
warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource may continue to run on the cluster indefinitely.
pod "pod-demo" force deleted
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods | grep pod-
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$

每个Pod都有一个pause镜像

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible 192.168.26.83 -m shell -a "docker ps | grep podcomm"
192.168.26.83 | CHANGED | rc=0 >>
c04e155aa25d   nginx                                                 "/docker-entrypoint.…"   21 minutes ago   Up 21 minutes             k8s_podcommon_podcommon_liruilong-pod-create_dbfc4fcd-d62b-4339-9f15-0a48802f60ad_0
309925812d42   registry.aliyuncs.com/google_containers/pause:3.4.1   "/pause"                 21 minutes ago   Up 21 minutes             k8s_POD_podcommon_liruilong-pod-create_dbfc4fcd-d62b-4339-9f15-0a48802f60ad_0

生成yaml文件的方式创建pod：-o yaml

kubectl run pod-demo --image=nginx --image-pull-policy=IfNotPresent --dry-run=client -o yaml >pod-demo.yaml

yaml文件的获取方法:-o yaml

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]  # yaml文件的获取方法:
└─$kubectl run pod-demo --image=nginx --image-pull-policy=IfNotPresent --dry-run=client -o yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod-demo
  name: pod-demo
spec:
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: pod-demo
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

yaml文件创建pod

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl run pod-demo --image=nginx --image-pull-policy=IfNotPresent --dry-run=client -o yaml >pod-demo.yaml

pod-demo.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod-demo
  name: pod-demo
spec:
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: pod-demo
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

yaml文件创建pod

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl apply -f pod-demo.yaml
pod/pod-demo created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -o wide
NAME        READY   STATUS    RESTARTS   AGE   IP            NODE                         NOMINATED NODE   READINESS GATES
pod-demo    1/1     Running   0          27s   10.244.70.4   vms83.liruilongs.github.io   <none>           <none>
podcommon   1/1     Running   0          13m   10.244.70.3   vms83.liruilongs.github.io   <none>           <none>

删除pod：delete pod

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl delete pod pod-demo
pod "pod-demo" deleted
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -o wide
NAME        READY   STATUS    RESTARTS   AGE   IP            NODE                         NOMINATED NODE   READINESS GATES
podcommon   1/1     Running   0          14m   10.244.70.3   vms83.liruilongs.github.io   <none>           <none>

Pod指定命令/删除pod/批量创建Pod

创建pod时指定运行命令。替换镜像中CMD的命令

方式一

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl run comm-pod --image=nginx --image-pull-policy=IfNotPresent --dry-run=client -o yaml -- "echo liruilong"
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: comm-pod
  name: comm-pod
spec:
  containers:
  - args:
    - echo liruilong
    image: nginx
    imagePullPolicy: IfNotPresent
    name: comm-pod
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

方式二

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl run comm-pod --image=nginx --image-pull-policy=IfNotPresent --dry-run=client -o yaml -- sh -c "echo liruilong"
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: comm-pod
  name: comm-pod
spec:
  containers:
  - args:
    - sh
    - -c
    - echo liruilong
    image: nginx
    imagePullPolicy: IfNotPresent
    name: comm-pod
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

kubectl delete -f comm-pod.yaml删除pod

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl run comm-pod --image=nginx --image-pull-policy=IfNotPresent --dry-run=client -o yaml -- sh c "echo liruilong"  > comm-pod.yaml
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl apply  -f comm-pod.yaml
pod/comm-pod created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl  delete  -f comm-pod.yaml
pod "comm-pod" deleted

批量创建pod

通过 sed 更改 pod名字的方式：sed ‘s/demo/demo1/’ demo.yaml | kubectl apply -f -

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$sed 's/demo/demo1/' demo.yaml  | kubectl apply -f -
pod/demo1 created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$sed 's/demo/demo2/' demo.yaml  | kubectl create -f -
pod/demo2 created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods -o wide
NAME          READY   STATUS    RESTARTS   AGE     IP               NODE                         NOMINATED NODE   READINESS GATES
demo1         1/1     Running   0          3m29s   10.244.70.32     vms83.liruilongs.github.io   <none>           <none>
demo2         1/1     Running   0          3m6s    10.244.70.33     vms83.liruilongs.github.io   <none>           <none>
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$

容器共享pod的网络空间的。即使用同一个IP地址：pod IP

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible 192.168.26.83 -m shell  -a "docker ps | grep demo1"
192.168.26.83 | CHANGED | rc=0 >>
0d644ad550f5   87a94228f133                                          "/docker-entrypoint.…"   8 minutes ago    Up 8 minutes              k8s_demo1_demo1_liruilong-pod-create_b721b109-a656-4379-9d3c-26710dadbf70_0
0bcffe0f8e2d   registry.aliyuncs.com/google_containers/pause:3.4.1   "/pause"                 8 minutes ago    Up 8 minutes              k8s_POD_demo1_liruilong-pod-create_b721b109-a656-4379-9d3c-26710dadbf70_0
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$ansible 192.168.26.83 -m shell  -a "docker inspect 0d644ad550f5 | grep -i ipaddress "
192.168.26.83 | CHANGED | rc=0 >>
            "SecondaryIPAddresses": null,
            "IPAddress": "",

pod多容器创建

一个pod内创建多个容器

comm-pod.yaml 文件编写

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: comm-pod
  name: comm-pod
spec:
  containers:
  - args:
    - sh
    - -c
    - echo liruilong;sleep 10000
    image: nginx
    imagePullPolicy: IfNotPresent
    name: comm-pod0
    resources: {}
  - name: comm-pod1
    image: nginx
    imagePullPolicy: IfNotPresent
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

创建多容器pod


┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl  apply  -f comm-pod.yaml
pod/comm-pod created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl  get pods
NAME          READY   STATUS    RESTARTS   AGE
comm-pod      2/2     Running   0          20s

镜像的下载策略

--image-pull-policy

Always 每次都下载最新镜像
Never 只使用本地镜像，从不下载
IfNotPresent 本地没有才下载

pod的重启策略

restartPolicy–单个容器正常退出

Always 总是重启
OnFailure 非正常退出才重启
Never 从不重启

labels 标签

k8s中每个资源对象都有标签

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get nodes --show-labels
NAME                         STATUS   ROLES                  AGE   VERSION   LABELS
vms81.liruilongs.github.io   Ready    control-plane,master   8d    v1.21.1   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=vms81.liruilongs.github.io,kubernetes.io/os=linux,node-role.kubernetes.io/control-plane=,node-role.kubernetes.io/master=,node.kubernetes.io/exclude-from-external-load-balancers=
vms82.liruilongs.github.io   Ready    <none>                 8d    v1.21.1   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=vms82.liruilongs.github.io,kubernetes.io/os=linux
vms83.liruilongs.github.io   Ready    <none>                 8d    v1.21.1   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=vms83.liruilongs.github.io,kubernetes.io/os=linux
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods --show-labels
NAME        READY   STATUS    RESTARTS   AGE   LABELS
podcommon   1/1     Running   0          87s   name=liruilong

查看标签

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl  get pods --show-labels
NAME          READY   STATUS    RESTARTS   AGE     LABELS
comm-pod      2/2     Running   0          4m43s   run=comm-pod
mysql-577h7   1/1     Running   0          93m     app=mysql
myweb-4xlc5   1/1     Running   0          92m     app=myweb
myweb-ltqdt   1/1     Running   0          91m     app=myweb

指定标签过滤

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl  get pods -l run=comm-pod
NAME       READY   STATUS    RESTARTS   AGE
comm-pod   2/2     Running   0          5m12s
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$

pod的状态

pod的状态	–
`Pending pod`	因为其他的原因导致pod准备开始创建还没有创建（卡住了）
`Running pod`	已经被调度到节点上，且容器工作正常
`Completed pod`	里所有容器正常退出
`error/CrashLoopBackOff`	创建的时候就出错，属于内部原因
`imagePullBackoff`	创建pod的时候，镜像下载失败

三、Pod的基本操作

在pod里执行命令，查看pod详细信息。查看pod日志

kubectl exec 命令
kubectl exec -it pod sh #如果pod里有多个容器，则命令是在第一个容器里执行
kubectl exec -it demo -c demo1 sh  # 指定容器
kubectl describe pod pod名
kubectl logs pod名 -c 容器名 #如果有多个容器的话 查看日志。
kubectl edit pod pod名 # 部分可以修改，有些不能修改

查看pod详细信息

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl describe  pod demo1
Name:         demo1
Namespace:    liruilong-pod-create
Priority:     0
Node:         vms83.liruilongs.github.io/192.168.26.83
Start Time:   Wed, 20 Oct 2021 22:27:15 +0800
Labels:       run=demo1
Annotations:  cni.projectcalico.org/podIP: 10.244.70.32/32
              cni.projectcalico.org/podIPs: 10.244.70.32/32
Status:       Running
IP:           10.244.70.32
IPs:
  IP:  10.244.70.32
Containers:
  demo1:
    Container ID:   docker://0d644ad550f59029036fd73d420d4d2c651801dd12814bb26ad8e979dc0b59c1
    Image:          nginx
    Image ID:       docker-pullable://nginx@sha256:644a70516a26004c97d0d85c7fe1d0c3a67ea8ab7ddf4aff193d9f301670cf36
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Wed, 20 Oct 2021 22:27:20 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-scc89 (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  kube-api-access-scc89:
    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  13m   default-scheduler  Successfully assigned liruilong-pod-create/demo1 to vms83.liruilongs.github.io
  Normal  Pulled     13m   kubelet            Container image "nginx" already present on machine
  Normal  Created    13m   kubelet            Created container demo1
  Normal  Started    13m   kubelet            Started container demo1

在pod里执行命令

kubectl exec -it demo1 -- ls /tmp

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl exec -it demo1 -- sh
# 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
# exit

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl exec -it demo1 -- bash
root@demo1:/# 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
root@demo1:/# exit
exit

Pod多个容器需要用-c指定

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl exec  comm-pod -c comm-pod1 -- echo liruilong
liruilong

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl exec -it  comm-pod -c comm-pod1 -- sh
# ls
bin  boot  dev  docker-entrypoint.d  docker-entrypoint.sh  etc  home  lib  lib64  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
# exit
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$#

查看日志

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl logs demo1
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2021/10/20 14:27:21 [notice] 1#1: using the "epoll" event method
2021/10/20 14:27:21 [notice] 1#1: nginx/1.21.3
2021/10/20 14:27:21 [notice] 1#1: built by gcc 8.3.0 (Debian 8.3.0-6)
2021/10/20 14:27:21 [notice] 1#1: OS: Linux 3.10.0-693.el7.x86_64
2021/10/20 14:27:21 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
2021/10/20 14:27:21 [notice] 1#1: start worker processes
2021/10/20 14:27:21 [notice] 1#1: start worker process 32
2021/10/20 14:27:21 [notice] 1#1: start worker process 33
┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$

拷贝文件

和docke一样的，可以相互拷贝

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl  cp /etc/hosts  comm-pod:/usr/share/nginx/html -c  comm-pod1
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl exec  comm-pod -c comm-pod1 -- ls /usr/share/nginx/html
50x.html
hosts
index.html

pod里运行命令

command的执行方式一：

apiVersion: v1
kind: Pod
metadata:
  name: myapp-pod
  labels:
    app: myapp
spec:
  containers: 
  - name: myapp-container
    image: busybox
    command: ['sh', '-c', 'echo OK! && sleep 60']

command的执行方式二：

apiVersion: v1
kind: Pod
metadata:
  name: myapp-pod
  labels:
    app: myapp
spec:
  containers: 
  - name: myapp-container
    image: busybox
    command: 
    - sh
    - -c
    - echo OK! && sleep 60

优雅的关闭pod:pod的延期删除

k8s对于pod的删除有一个延期的删除期，即宽限期，这个时间默认为30s,如果删除时加了 --force选项，就会强制删除。

在删除宽限期内，节点状态被标记为treminating ,宽限期结束后删掉pod，这里的宽限期通过参数 terminationGracePeriodSeconds 设定

┌──[root@vms81.liruilongs.github.io]-[~/ansible]
└─$kubectl explain pod.spec
....
  terminationGracePeriodSeconds        <integer>
   pod需要优雅终止的可选持续时间(以秒为单位)。可在删除请求中增加。值必须是非负整数。
   值0表示通过kill信号立即停止(没有机会关机)。如果该值为null，则使用默认的宽限期。
   宽限期是在pod中运行的进程收到终止信号后的持续时间(以秒为单位)，以及进程被kill信号强制停止的时间。
   设置此值比流程的预期清理时间长。默认为30秒。

如果pod里面是Nginx进程，就不行，Nginx的处理信号的方式和k8s不同，当我们使用Nginx作为镜像来生成一个个pod的时候，pod里面的Nginx进程就会被很快的关闭，之后的pod也会被删除，并不会使用k8s的宽限期

terminationGracePeriodSeconds: 600

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: demo
  name: demo
spec:
  terminationGracePeriodSeconds: 600
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: demo
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

当某个pod正在被使用是，突然关闭，那这个时候我们还想处理一些事情，这里可以用 pod hook

pod生命周期

pod hook(钩子)

hook是一个很常见的功能，有时候也称回调，即在到达某一预期事件时触发的操作，比如前端框架 Vue 的生命周期回调函数，java 虚拟机 JVM 在进程结束时的钩子线程。

在pod的整个生命周期内，有两个回调可以使用

两个回调可以使用
postStart：当创建pod的时候调用，会随着pod里的主进程同时运行，并行操作，没有先后顺序
preStop：当删除pod的时候创建，要先运行perStop里的程序，之后在关闭pod,这里的preStop必须是在pod的宽限期内完成，没有完成pod也会被强制删除

修改yaml文件:demo.yaml

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: demo
  name: demo
spec:
  terminationGracePeriodSeconds: 600
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: demo
    resources: {}
    lifecycle:
      postStart:
        exec:
          command: ["bin/sh", "-c","echo liruilong`date` >> /liruilong"]
      preStop:
        exec:
          command: ["bin/sh","-c","use/sbin/nginx -s quit"]
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

下面我们创建一个带钩子的pod

┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl  apply  -f demo.yaml
pod/demo created
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl get pods
NAME          READY   STATUS    RESTARTS   AGE
demo          1/1     Running   0          21s
┌──[root@vms81.liruilongs.github.io]-[~/ansible/k8s-pod-create]
└─$kubectl exec -it demo  -- bin/bash
root@demo:/# ls
bin   dev                  docker-entrypoint.sh  home  lib64      media  opt   root  sbin  sys  usr
boot  docker-entrypoint.d  etc                   lib   liruilong  mnt    proc  run   srv   tmp  var
root@demo:/# cat liruilong
liruilongSun Nov 14 05:10:51 UTC 2021
root@demo:/#

这里关闭的话，主进程不会等到宽限期结束，会找Ngixn收到关闭信号时直接关闭

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关于 Kubernetes中Pod的一些笔记（一）

写在前面

一、帮助文档的使用

二、创建Pod的方式

新建命名空间:

命令行的方式创建pod

查看pod调度到了那个节点

删除pod

生成yaml文件的方式创建pod：-o yaml

Pod指定命令/删除pod/批量创建Pod

pod多容器创建

镜像的下载策略

pod的重启策略

labels 标签

pod的状态

三、Pod的基本操作

查看pod详细信息

在pod里执行命令

查看日志

拷贝文件

pod里运行命令

优雅的关闭pod:pod的延期删除

pod生命周期

pod hook(钩子)

全部回复

设置昵称

关于作者

目录

加入云驻计划，成为创作者

关于 Kubernetes中Pod的一些笔记（一）

写在前面

一、帮助文档的使用

二、创建Pod的方式

新建命名空间:

命令行的方式创建pod

查看pod调度到了那个节点

删除pod

生成yaml文件的方式创建pod：-o yaml

Pod指定命令/删除pod/批量创建Pod

pod多容器创建

镜像的下载策略

pod的重启策略

labels 标签

pod的状态

三、Pod的基本操作

查看pod详细信息

在pod里执行命令

查看日志

拷贝文件

pod里运行命令

优雅的关闭pod:pod的延期删除

pod生命周期

pod hook(钩子)

全部回复

设置昵称

关于作者

目录

加入云驻计划，成为创作者

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