【容器应用系列教程】Kubernetes的Pod管理

一、关于Pod

k8s集群所能管理的最小单元
一个pod只放一个容器
支持一个pod放多个容器，不建议实际使用

二、Pod管理操作

1.创建`Pod`简单`yaml`文件示例

[root@k8s-master wordpress]# vim centos.yml

apiVersion: v1	#api版本
kind: Pod	#资源类型Pod
metadata:	#元数据
    name: centos	#名字
    namespace: wordpress	#指定在哪个命名空间里
spec:
    containers:	#容器信息
    - name: centos	#容器名字
      image: centos:7	#使用的镜像
      tty: true	#模拟一个终端
      command:	#启动容器时，执行的命令
      - bash

apiVersion：指定api server版本，目前是v1
kind:说明要创建的资源类型
metadata:指定Pod的元数据信息
- name:指定pod名称
- namespace:指定Pod所在的命名空间，不写代表default
spec:定义pod中运行的容器的具体信息

[root@k8s-master wordpress]# kubectl create -f ./centos.yml 	#创建Pod
pod/centos created

2.查看`Pod`

[root@k8s-master wordpress]# kubectl get pods -n wordpress
NAME     READY   STATUS    RESTARTS   AGE
centos   1/1     Running   0          64s

-n指定命名空间

查看`Pod`的详细信息

[root@k8s-master wordpress]# kubectl get pods -n wordpress -o wide
NAME     READY   STATUS    RESTARTS   AGE     IP                NODE                   NOMINATED NODE   READINESS GATES
centos   1/1     Running   0          6m59s   192.168.201.202   k8s-node01.linux.com   <none>           <none>

-o wide显示详细信息

查看所有`Pod`

[root@k8s-master wordpress]# kubectl get pods  -A

NAMESPACE     NAME                                           READY   STATUS    RESTARTS   AGE
kube-system   calico-kube-controllers-5f6d4b864b-2pqz6       1/1     Running   1          3d
kube-system   calico-node-fld77                              1/1     Running   1          2d23h
kube-system   calico-node-h2kxd                              1/1     Running   1          2d23h
kube-system   calico-node-vfltp                              1/1     Running   1          2d23h
kube-system   coredns-54d67798b7-cbq9r                       1/1     Running   1          2d23h
kube-system   coredns-54d67798b7-ch5hw                       1/1     Running   1          2d23h
kube-system   etcd-k8s-master.linux.com                      1/1     Running   1          3d2h
kube-system   kube-apiserver-k8s-master.linux.com            1/1     Running   1          3d2h
kube-system   kube-controller-manager-k8s-master.linux.com   1/1     Running   1          3d2h
kube-system   kube-proxy-6pq4t                               1/1     Running   1          3d2h
kube-system   kube-proxy-gb66k                               1/1     Running   1          3d2h
kube-system   kube-proxy-zcjrc                               1/1     Running   1          3d2h
kube-system   kube-scheduler-k8s-master.linux.com            1/1     Running   1          3d2h
wordpress     centos                                         1/1     Running   0          5m17s

查看所有`Pod`的详细信息

[root@k8s-master wordpress]# kubectl get pods -A -o wide

NAMESPACE     NAME                                           READY   STATUS    RESTARTS   AGE     IP                NODE                   NOMINATED NODE   READINESS GATES
kube-system   calico-kube-controllers-5f6d4b864b-2pqz6       1/1     Running   1          3d      192.168.140.10    k8s-master.linux.com   <none>           <none>
kube-system   calico-node-fld77                              1/1     Running   1          3d      192.168.140.11    k8s-node01.linux.com   <none>           <none>
kube-system   calico-node-h2kxd                              1/1     Running   1          3d      192.168.140.12    k8s-node02.linux.com   <none>           <none>
kube-system   calico-node-vfltp                              1/1     Running   1          3d      192.168.140.10    k8s-master.linux.com   <none>           <none>
kube-system   coredns-54d67798b7-cbq9r                       1/1     Running   1          3d      192.168.201.194   k8s-node01.linux.com   <none>           <none>
kube-system   coredns-54d67798b7-ch5hw                       1/1     Running   1          3d      192.168.242.130   k8s-node02.linux.com   <none>           <none>
kube-system   etcd-k8s-master.linux.com                      1/1     Running   1          3d2h    192.168.140.10    k8s-master.linux.com   <none>           <none>
kube-system   kube-apiserver-k8s-master.linux.com            1/1     Running   1          3d2h    192.168.140.10    k8s-master.linux.com   <none>           <none>
kube-system   kube-controller-manager-k8s-master.linux.com   1/1     Running   1          3d2h    192.168.140.10    k8s-master.linux.com   <none>           <none>
kube-system   kube-proxy-6pq4t                               1/1     Running   1          3d2h    192.168.140.11    k8s-node01.linux.com   <none>           <none>
kube-system   kube-proxy-gb66k                               1/1     Running   1          3d2h    192.168.140.10    k8s-master.linux.com   <none>           <none>
kube-system   kube-proxy-zcjrc                               1/1     Running   1          3d2h    192.168.140.12    k8s-node02.linux.com   <none>           <none>
kube-system   kube-scheduler-k8s-master.linux.com            1/1     Running   1          3d2h    192.168.140.10    k8s-master.linux.com   <none>           <none>
wordpress     centos                                         1/1     Running   0          8m53s   192.168.201.202   k8s-node01.linux.com   <none>           <none>

3.查看某一个`Pod`创建信息和详细信息

也可以用来判断长时间处于创建状态的Pod或者异常状态的Pod

[root@k8s-master wordpress]# kubectl describe pods centos -n wordpress

Name:         centos
Namespace:    wordpress
Priority:     0
Node:         k8s-node01.linux.com/192.168.140.11
Start Time:   Mon, 12 Jun 2023 18:50:12 +0800
Labels:       <none>
Annotations:  <none>
Status:       Running
IP:           192.168.201.202
IPs:
  IP:  192.168.201.202
Containers:
  centos:
    Container ID:  docker://e25dd6ee071b53d167c42148ae81b3f9ac26d5933b9025e04898c0a89d6212b7
    Image:         centos:7
    Image ID:      docker-pullable://centos@sha256:be65f488b7764ad3638f236b7b515b3678369a5124c47b8d32916d6487418ea4
    Port:          <none>
    Host Port:     <none>
    Command:
      bash
    State:          Running
      Started:      Mon, 12 Jun 2023 18:50:13 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-f9cxl (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-f9cxl:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-f9cxl
    Optional:    false
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  10m   default-scheduler  Successfully assigned wordpress/centos to k8s-node01.linux.com
  Normal  Pulled     10m   kubelet            Container image "centos:7" already present on machine
  Normal  Created    10m   kubelet            Created container centos
  Normal  Started    10m   kubelet            Started container centos

4.连接`Pod`

[root@k8s-master wordpress]# kubectl exec -it centos -n wordpress -- /bin/bash
[root@centos /]#

5.删除`Pod`

[root@k8s-master wordpress]# kubectl delete -f ./centos.yml 
pod "centos" deleted

或者使用下面的命令，直接删除Pod

[root@k8s-master wordpress]# kubectl delete pod centos -n wordpress
pod "centos" deleted

三、`containers`常用选项

apiVersion: v1
kind: 资源类型
metadata:
    name: 自定义名字
    namespace: 命名空间名
spec:
    containers:	
    选项：参数
    选项：参数

1.`name`容器名称

spec:
    containers:
    - name: centos	#自定义容器名称

2.`image`镜像名字

spec:
    containers:
    - name: centos
      image: centos:7	#使用Centos镜像7版本

3.`imagePullPolicy: [Always | Never | IfNotPresent ]`拉取镜像策略

Always: 每次执行yaml文件时，都重新拉取镜像
Never: 不拉取镜像
IfNotPresent: 如果本地没有，则拉取镜像，有则直接使用

spec:
    containers:
    - name: centos
      image: centos:7
      imagePullPolicy: IfNotPresent

4.`restartPolicy [ Always | Never | OnFailure]`容器重启动策略

Always:只要容器挂掉，都重启
Never:容器挂掉，忽略不管
OnFailure:只有在容器异常退出时，重启；如果是正常退出，则不管
资源类型为Pod时无法使用，只有类型是Deployment时才有效

5.`command`启动容器时执行的命令

spec:
    containers:
    - name: centos
      image: centos:7
      imagePullPolicy: IfNotPresent
      tty: true
      command:
      - bash

`args`向`command`传递参数

apiVersion: v1
kind: Pod
metadata:
    name: centos
    namespace: wordpress
spec:
    containers:
    - name: centos
      image: centos:7
      imagePullPolicy: IfNotPresent
      command:
      - ping
      args:
      - "baidu.com"

6.`ports`说明容器要发布的端口

不是服务发布，仅仅是说明容器要发布的端口

apiVersion: v1
kind: Pod
metadata:
    name: centos
    namespace: wordpress
spec:
    containers:
    - name: centos
      image: centos:7
      imagePullPolicy: IfNotPresent
      command:
      - ping
      - "baidu.com"	#上面命令参数，也可以这么写
      ports:
      - containerPort: 22	#说明要发布22号端口

[root@k8s-master wordpress]# kubectl describe pod centos -n wordpress | grep -i "port"
    Port:          22/TCP
    Host Port:     0/TCP

7.`env`向容器内传递变量

apiVersion: v1
kind: Pod
metadata:
    name: centos
    namespace: wordpress
spec:
    containers:
    - name: centos
      image: centos:7
      imagePullPolicy: IfNotPresent
      command:
      - ping
      - "baidu.com"
      ports:
      - containerPort: 22
      env:
      - name: wsjj	#定义变量wsjj
        value: wangshengjj	#变量值为wangshengjj

[root@k8s-master wordpress]# kubectl exec -it centos -n wordpress -- bash
[root@centos /]# echo $wsjj
wangshengjj

8.`resources`资源限制

容器cpu,内存资源限制
1000豪核 = 1CPU

apiVersion: v1
kind: Pod
metadata:
    name: centos
    namespace: wordpress
spec:
    containers:
    - name: centos
      image: centos:7
      imagePullPolicy: IfNotPresent
      command:
      - ping
      - "baidu.com"
      resources:
            requests:	#软限制
                memory: "1G"
                cpu: "500m"	#1核的一半性能
            limits:	#硬限制
                memory: "2G"
                cpu: "1"	#最多1核

9.健康状态检查、探针

检查方式

LivenessProbe
- 判断容器是否健康，如果不健康, kubelet将删除该容器并根据重启策略做相应的处理
ReadinessProbe
- 判断容器是否启动完成且准备接受请求；如果检测失败，则endpoint会被从service对应的endpoint中删除

livenessProbe:
    httpGet:	#使用get方法检测
        path: /check	#指定uri地址
        port: 80	#端口80
initialDelaySeconds: 3	#容器启动前3秒不检测
periodSeconds: 3	#检测3秒

10.案例

创建一个`Mysql5.7`的`Pod`

[root@k8s-master wordpress]# vim ./mysql.yaml

apiVersion: v1
kind: Pod
metadata:
    name: mysql
    namespace: wordpress
spec:
    containers:
        - name: mysql
          image: mysql:5.7
          imagePullPolicy: IfNotPresent
          ports:
          - containerPort: 3306
          env:
          - name: MYSQL_ROOT_PASSWORD
            value: "WWW.1.com"
          resources:
            requests:
              memory: "1G"
              cpu: "1"
            limits:
              memory: "2G"
              cpu: "2"

[root@k8s-master wordpress]# kubectl create -f ./mysql.yaml 
pod/mysql created

[root@k8s-master wordpress]# kubectl exec -it mysql -n wordpress -- bash

bash-4.2# mysql -uroot -pWWW.1.com
mysql>

【容器应用系列教程】Kubernetes的Pod管理

一、关于Pod

二、Pod管理操作

1.创建Pod简单yaml文件示例

2.查看Pod

查看Pod的详细信息

查看所有Pod

查看所有Pod的详细信息

3.查看某一个Pod创建信息和详细信息

4.连接Pod

5.删除Pod

三、containers常用选项

1.name容器名称

2.image镜像名字

3.imagePullPolicy: [Always | Never | IfNotPresent ]拉取镜像策略

4.restartPolicy [ Always | Never | OnFailure]容器重启动策略

5.command启动容器时执行的命令

args向command传递参数

6.ports说明容器要发布的端口

7.env向容器内传递变量

8.resources资源限制

9.健康状态检查、探针

检查方式

10.案例

创建一个Mysql5.7的Pod

1.创建`Pod`简单`yaml`文件示例

2.查看`Pod`

查看`Pod`的详细信息

查看所有`Pod`

查看所有`Pod`的详细信息

3.查看某一个`Pod`创建信息和详细信息

4.连接`Pod`

5.删除`Pod`

三、`containers`常用选项

1.`name`容器名称

2.`image`镜像名字

3.`imagePullPolicy: [Always | Never | IfNotPresent ]`拉取镜像策略

4.`restartPolicy [ Always | Never | OnFailure]`容器重启动策略

5.`command`启动容器时执行的命令

`args`向`command`传递参数

6.`ports`说明容器要发布的端口

7.`env`向容器内传递变量

8.`resources`资源限制

创建一个`Mysql5.7`的`Pod`