k8s------pod详解2
一、pod生命周期
我们一般将pod对象从创建至终的这段时间范围称为pod的生命周期，它主要包含下面的过程：
1、pod创建过程
2、运行初始化容器（init container）过程
3、运行主容器（main container）
（1）容器启动后钩子（post start）、容器终止前钩子（pre stop）
（2）容器的存活性探测（liveness probe）、就绪性探测（readiness probe）
4、pod终止过程
在整个生命周期中，Pod会出现5种状态 （相位），分别如下：
1、挂起（Pending）：apiserver已经创建了pod资源对象，但它尚未被调度完成或者仍处于下载镜像的过程中
2、运行中（Running）：pod已经被调度至某节点，并且所有容器都已经被kubelet创建完成
3、成功（Succeeded）：pod中的所有容器都已经成功终止并且不会被重启
4、失败（Failed）：所有容器都已经终止，但至少有一个容器终止失败，即容器返回了非0值的退出状态
5、未知（Unknown）：apiserver无法正常获取到pod对象的状态信息，通常由网络通信失败所导致
二、创建和终止
pod的创建过程
1、用户通过kubectl或其他api客户端提交需要创建的pod信息给apiServer
2、apiServer开始生成pod对象的信息，并将信息存入etcd，然后返回确认信息至客户端
3、apiServer开始反映etcd中的pod对象的变化，其它组件使用watch机制来跟踪检查apiServer上的变动
4、scheduler发现有新的pod对象要创建，开始为Pod分配主机并将结果信息更新至apiServer
5、node节点上的kubelet发现有pod调度过来，尝试调用docker启动容器，并将结果回送至apiServer
6、apiServer将接收到的pod状态信息存入etcd中
pod的终止过程
1、用户向apiServer发送删除pod对象的命令
2、apiServcer中的pod对象信息会随着时间的推移而更新，在宽限期内（默认30s），pod被视为dead
3、将pod标记为terminating状态
4、 kubelet在监控到pod对象转为terminating状态的同时启动pod关闭过程
5、节点控制器监控到pod对象的关闭行为时将其从所有匹配到此节点的service资源的节点列表中移除
6、 如果当前pod对象定义了preStop钩子处理器，则在其标记为terminating后即会以同步的方式启动执行
7、pod对象中的容器进程收到停止信号
8、宽限期结束后，若pod中还存在仍在运行的进程，那么pod对象会收到立即终止的信号
9、kubelet请求apiServer将此pod资源的宽限期设置为0从而完成删除操作，此时pod对于用户已不可见
三、初始化容器
初始化容器是在pod的主容器启动之前要运行的容器，主要是做一些主容器的前置工作 ，它具有两大特征：
初始化容器必须运行完成直至结束，若某初始化容器运行失败，那么kubernetes需要重启它直到成功完成
初始化容器必须按照定义的顺序执行，当且仅当前一个成功之后，后面的一个才能运行
初始化容器有很多的应用场景，下面列出的是最常见的几个：
（1）提供主容器镜像中不具备的工具程序或自定义代码
（2）初始化容器要先于应用容器串行启动并运行完成，因此可用于延后应用容器的启动直至其依赖的条件得到满足
接下来做一个案例，模拟下面这个需求：
假设要以主容器来运行nginx，但是要求在运行nginx之前先要能够连接上mysql和redis所在服务器
为了简化测试，事先规定好mysql（192.168.100.10）和redis（192.168.100.20）服务器的地址
1、创建pod-initcontainer.yaml
powershell
[root@master ~]# vim pod-initcontainer.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-initcontainer
namespace: dev
spec:
containers:
- name: main-container
image: nginx:1.17.1
ports:
- name: nginx-port
containerPort: 80
initContainers:
- name: test-mysql
image: busybox:1.30
command: ['sh', '-c', 'until ping 192.168.100.110 -c 1 ; do echo waiting for mysql...; sleep 2; done;']
- name: test-redis
image: busybox:1.30
command: ['sh', '-c', 'until ping 192.168.100.120 -c 1 ; do echo waiting for reids...; sleep 2; done;']2、创建pod，查看pod状态
powershell
[root@master ~]# kubectl apply -f pod-initcontainer.yaml
pod/pod-initcontainer created
[root@master ~]# kubectl describe pod pod-initcontainer -n dev
Name: pod-initcontainer
Namespace: dev
Priority: 0
Service Account: default
Node: node1/192.168.100.110
Start Time: Mon, 03 Nov 2025 17:16:08 +0800
Labels: <none>
......
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 4s default-scheduler Successfully assigned dev/pod-initcontainer to node1
Normal Pulled 1s kubelet Container image "busybox:1.30" already present on machine
Normal Created 1s kubelet Created container test-mysql
Normal Started 0s kubelet Started container test-mysql
Normal Pulled 0s kubelet Container image "busybox:1.30" already present on machine
Normal Created 0s kubelet Created container test-redis
Normal Started 0s kubelet Started container test-redis
Normal Pulled 0s kubelet Container image "nginx:1.17.1" already present on machine
Normal Created 0s kubelet Created container main-container
Normal Started 0s kubelet Started container main-container
# 动态查看pod
[root@master ~]# kubectl get pods pod-initcontainer -n dev -w
NAME READY STATUS RESTARTS AGE
pod-initcontainer 1/1 Running 0 33s验证了 Init Container 的核心特性："先于主容器启动且顺序执行"
Init Container 的核心逻辑在实验中完全体现，这是主容器稳定运行的前置保障。
- 执行顺序优先 ：实验中
test-mysql和test-redis两个 Init Container 会严格按定义顺序执行，只有前一个成功完成，后一个才会启动。 - 主容器启动条件 ：只有所有 Init Container 都执行成功（返回 0 状态码），Kubernetes 才会启动
main-container（Nginx 容器）；只要有一个 Init Container 未完成，主容器就会一直等待。
三、钩子函数
钩子函数能够感知自身生命周期中的事件，并在相应的时刻到来时运行用户指定的程序代码。
kubernetes在主容器的启动之后和停止之前提供了两个钩子函数：
post start：容器创建之后执行，如果失败了会重启容器
pre stop ：容器终止之前执行，执行完成之后容器将成功终止，在其完成之前会阻塞删除容器的操作
钩子处理器支持使用下面三种方式定义动作：
Exec命令：在容器内执行一次命令
TCPSocket：在当前容器尝试访问指定的socket
HTTPGet：在当前容器中向某url发起http请求
1、以exec方式为例，演示下钩子函数的使用，创建pod-hook-exec.yaml文件
powershell
[root@master ~]# vim pod-hook-exec.yaml
[root@master ~]# cat pod-hook-exec.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-hook-exec
namespace: dev
spec:
containers:
- name: main-container
image: nginx:1.17.1
ports:
- name: nginx-port
containerPort: 80
lifecycle:
postStart:
exec: # 在容器启动的时候执行一个命令，修改掉nginx的默认首页内容
command: ["/bin/sh", "-c", "echo postStart... > /usr/share/nginx/html/index.html"]
preStop:
exec: # 在容器停止之前停止nginx服务
command: ["/usr/sbin/nginx","-s","quit"]
# 创建pod
[root@master ~]# kubectl apply -f pod-hook-exec.yaml
pod/pod-hook-exec created
# 查看pod
[root@master ~]# kubectl get pods pod-hook-exec -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-hook-exec 1/1 Running 0 36s 172.16.166.152 node1 <none> <none>
# 访问pod
[root@master ~]# curl 172.16.166.152
postStart...四、容器探测
容器探测用于检测容器中的应用实例是否正常工作，是保障业务可用性的一种传统机制。如果经过探测，实例的状态不符合预期，那么kubernetes就会把该问题实例" 摘除 "，不承担业务流量。kubernetes提供了两种探针来实现容器探测，分别是：
liveness probes：存活性探针，用于检测应用实例当前是否处于正常运行状态，如果不是，k8s会重启容器
readiness probes：就绪性探针，用于检测应用实例当前是否可以接收请求，如果不能，k8s不会转发流量
livenessProbe 决定是否重启容器，readinessProbe 决定是否将请求转发给容器。
上面两种探针目前均支持三种探测方式：
Exec命令：在容器内执行一次命令，如果命令执行的退出码为0，则认为程序正常，否则不正常
TCPSocket：将会尝试访问一个用户容器的端口，如果能够建立这条连接，则认为程序正常，否则不正常
HTTPGet：调用容器内Web应用的URL，如果返回的状态码在200和399之间，则认为程序正常，否则不正常
以liveness probes为例，做几个演示：
1、方式一：Exec
（1）创建pod-liveness-exec.yaml
powershell
[root@master ~]# cat pod-liveness-exec.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-liveness-exec
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
ports:
- name: nginx-port
containerPort: 80
livenessProbe:
exec:
command: ["/bin/cat","/tmp/hello.txt"] # 执行一个查看文件的命令（2）创建pod，观察效果
powershell
[root@master ~]# kubectl apply -f pod-liveness-exec.yaml
pod/pod-liveness-exec created
# 查看Pod详情
[root@master ~]# kubectl describe pods pod-liveness-exec -n dev
Name: pod-liveness-exec
Namespace: dev
Priority: 0
Service Account: default
Node: node2/192.168.100.120
Start Time: Mon, 03 Nov 2025 17:49:32 +0800
Labels: <none>
......
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 33s default-scheduler Successfully assigned dev/pod-liveness-exec to node2
Normal Pulled <invalid> (x2 over 24s) kubelet Container image "nginx:1.17.1" already present on machine
Normal Created <invalid> (x2 over 24s) kubelet Created container nginx
Normal Started <invalid> (x2 over 23s) kubelet Started container nginx
Warning Unhealthy <invalid> (x3 over 15s) kubelet Liveness probe failed: /bin/cat: /tmp/hello.txt: No such file or directory
Normal Killing <invalid> kubelet Container nginx failed liveness probe, will be restarted
# 观察上面的信息就会发现nginx容器启动之后就进行了健康检查# 检查失败之后，容器被kill掉，然后尝试进行重启
# 稍等一会之后，再观察pod信息，就可以看到RESTARTS不再是0，而是一直增长
[root@master ~]# kubectl get pods pod-liveness-exec -n dev
NAME READY STATUS RESTARTS AGE
pod-liveness-exec 1/1 Running 2 (0s ago) 68s
[root@master ~]# kubectl get pods pod-liveness-exec -n dev
NAME READY STATUS RESTARTS AGE
pod-liveness-exec 1/1 Running 3 (0s ago) 97s
#由两次重启变为三次重启可以修改成一个存在的文件，比如/usr/share/nginx/html/index.html，再试，结果就正常了
powershell
[root@master ~]# cat pod-liveness-exec.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-liveness-exec
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
ports:
- name: nginx-port
containerPort: 80
livenessProbe:
exec:
command: ["/bin/cat","/usr/share/nginx/html/index.html"]
[root@master ~]# kubectl apply -f pod-liveness-exec.yaml
pod/pod-liveness-exec created
[root@master ~]# kubectl describe pods pod-liveness-exec -n dev
Name: pod-liveness-exec
Namespace: dev
Priority: 0
Service Account: default
Node: node2/192.168.100.120
Start Time: Mon, 03 Nov 2025 17:56:44 +0800
Labels: <none>
......
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 9s default-scheduler Successfully assigned dev/pod-liveness-exec to node2
Normal Pulled 0s kubelet Container image "nginx:1.17.1" already present on machine
Normal Created 0s kubelet Created container nginx
Normal Started 0s kubelet Started container nginx
[root@master ~]# kubectl get pods pod-liveness-exec -n dev
NAME READY STATUS RESTARTS AGE
pod-liveness-exec 1/1 Running 0 17s
[root@master ~]# kubectl get pods pod-liveness-exec -n dev
NAME READY STATUS RESTARTS AGE
pod-liveness-exec 1/1 Running 0 82s2、方式二：TCPSocket
（1）创建pod-liveness-tcpsocket.yaml
powershell
[root@master ~]# cat pod-liveness-tcpsocket.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-liveness-tcpsocket
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
ports:
- name: nginx-port
containerPort: 80
livenessProbe:
tcpSocket:
port: 8080 # 尝试访问8080端口（2）创建pod，观察效果
powershell
[root@master ~]# kubectl apply -f pod-liveness-tcpsocket.yaml
pod/pod-liveness-tcpsocket created
[root@master ~]# kubectl describe pods pod-liveness-tcpsocket -n dev
Name: pod-liveness-tcpsocket
Namespace: dev
Priority: 0
Service Account: default
Node: node2/192.168.100.120
Start Time: Mon, 03 Nov 2025 18:01:50 +0800
Labels: <none>
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 26s default-scheduler Successfully assigned dev/pod-liveness-tcpsocket to node2
Normal Pulled 17s kubelet Container image "nginx:1.17.1" already present on machine
Normal Created 17s kubelet Created container nginx
Normal Started 17s kubelet Started container nginx
Warning Unhealthy 0s (x2 over 8s) kubelet Liveness probe failed: dial tcp 172.16.104.26:8080: connect: connection refused
# 观察信息，发现尝试访问8080端口,但是失败了
# 稍等一会之后，再观察pod信息，就可以看到RESTARTS不再是0，而是一直增长
[root@master ~]# kubectl get pods pod-liveness-tcpsocket -n dev
NAME READY STATUS RESTARTS AGE
pod-liveness-tcpsocket 1/1 Running 1 (11s ago) 50s
[root@master ~]# kubectl get pods pod-liveness-tcpsocket -n dev
NAME READY STATUS RESTARTS AGE
pod-liveness-tcpsocket 1/1 Running 2 (12s ago) 81s
# 当然接下来，可以修改成一个可以访问的端口，比如80，再试，结果就正常了......3、方式三：HTTPGet
（1）创建pod-liveness-httpget.yaml
powershell
[root@master ~]# cat pod-liveness-httpget.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-liveness-httpget
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
ports:
- name: nginx-port
containerPort: 80
livenessProbe:
httpGet:
scheme: HTTP #支持的协议，http或者https
port: 80 #端口号
path: /file1 #URI地址
host: 192.168.100.120 #支持的主机（2）创建pod，观察效果
powershell
[root@master ~]# kubectl apply -f pod-liveness-httpget.yaml
pod/pod-liveness-httpget created
[root@master ~]# kubectl describe pods pod-liveness-httpget -n dev
Name: pod-liveness-httpget
Namespace: dev
Priority: 0
Service Account: default
Node: node2/192.168.100.120
Start Time: Mon, 03 Nov 2025 18:16:33 +0800
Labels: <none>
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 16s default-scheduler Successfully assigned dev/pod-liveness-httpget to node2
Normal Pulled 7s kubelet Container image "nginx:1.17.1" already present on machine
Normal Created 7s kubelet Created container nginx
Normal Started 7s kubelet Started container nginx
Warning Unhealthy 0s kubelet Liveness probe failed: HTTP probe failed with statuscode: 404
# 观察上面信息，尝试访问路径，但是未找到,出现404错误
# 稍等一会之后，再观察pod信息，就可以看到RESTARTS不再是0，而是一直增长
[root@master ~]# kubectl get pods pod-liveness-httpget -n dev
NAME READY STATUS RESTARTS AGE
pod-liveness-httpget 1/1 Running 1 (6s ago) 44s
[root@master ~]# kubectl get pods pod-liveness-httpget -n dev
NAME READY STATUS RESTARTS AGE
pod-liveness-httpget 1/1 Running 3 (13s ago) 111s（3）可以修改成一个可以访问的路径path，比如/file2，再试，结果就正常了
node2：
powershell
[root@node2 ~]# yum -y install httpd
[root@node2 ~]# cd /var/www/html
[root@node2 html]# echo 123 > file2
[root@node2 html]# cat file2
123
[root@node2 html]# systemctl restart httpd
[root@node2 html]# systemctl enable httpd
Created symlink /etc/systemd/system/multi-user.target.wants/httpd.service → /usr/lib/systemd/system/httpd.service.master：
powershell
[root@master ~]# cat pod-liveness-httpget.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-liveness-httpget
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
ports:
- name: nginx-port
containerPort: 80
livenessProbe:
httpGet:
scheme: HTTP
port: 80
path: /file2
host: 192.168.100.120
[root@master ~]# kubectl apply -f pod-liveness-httpget.yaml
pod/pod-liveness-httpget created
[root@master ~]# kubectl describe pods pod-liveness-httpget -n dev
Name: pod-liveness-httpget
Namespace: dev
Priority: 0
Service Account: default
Node: node1/192.168.100.110
Start Time: Mon, 03 Nov 2025 18:20:47 +0800
Labels: <none>
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 4s default-scheduler Successfully assigned dev/pod-liveness-httpget to node1
Normal Pulled <invalid> kubelet Container image "nginx:1.17.1" already present on machine
Normal Created <invalid> kubelet Created container nginx
Normal Started <invalid> kubelet Started container nginx
[root@master ~]# curl 192.168.100.120/file2
123至此，已经使用liveness Probe演示了三种探测方式，但是查看livenessProbe的子属性，会发现除了这三种方式，还有一些其他的配置，在这里一并解释下：
powershell
[root@master ~]# kubectl explain pod.spec.containers.livenessProbe
FIELDS:
exec <Object>
tcpSocket <Object>
httpGet <Object>
initialDelaySeconds <integer> # 容器启动后等待多少秒执行第一次探测
timeoutSeconds <integer> # 探测超时时间。默认1秒，最小1秒
periodSeconds <integer> # 执行探测的频率。默认是10秒，最小1秒
failureThreshold <integer> # 连续探测失败多少次才被认定为失败。默认是3。最小值是1
successThreshold <integer> # 连续探测成功多少次才被认定为成功。默认是1五、重启策略
在上一节中，一旦容器探测出现了问题，kubernetes就会对容器所在的Pod进行重启，其实这是由pod的重启策略决定的，pod的重启策略有 3 种，分别如下：
Always ：容器失效时，自动重启该容器，这也是默认值
OnFailure ： 容器终止运行且退出码不为0时重启
Never ： 不论状态为何，都不重启该容器
重启策略适用于pod对象中的所有容器，首次需要重启的容器，将在其需要时立即进行重启，随后再次需要重启的操作将由kubelet延迟一段时间后进行，且反复的重启操作的延迟时长以此为10s、20s、40s、80s、160s和300s，300s是最大延迟时长。
1、创建pod-restartpolicy.yaml
powershell
[root@master ~]# cat pod-restartpolicy.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-restartpolicy
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
ports:
- name: nginx-port
containerPort: 80
livenessProbe:
httpGet:
scheme: HTTP
port: 80
path: /hello
restartPolicy: Never # 设置重启策略为Never2、运行Pod测试
powershell
[root@master ~]# kubectl apply -f pod-restartpolicy.yaml
pod/pod-restartpolicy created
# 查看Pod详情，发现nginx容器失败
[root@master ~]# kubectl describe pods pod-restartpolicy -n dev
Name: pod-restartpolicy
Namespace: dev
Priority: 0
Service Account: default
Node: node2/192.168.100.120
Start Time: Mon, 03 Nov 2025 18:33:01 +0800
Labels: <none>
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 25s default-scheduler Successfully assigned dev/pod-restartpolicy to node2
Normal Pulled 16s kubelet Container image "nginx:1.17.1" already present on machine
Normal Created 16s kubelet Created container nginx
Normal Started 16s kubelet Started container nginx
Warning Unhealthy <invalid> (x2 over 7s) kubelet Liveness probe failed: HTTP probe failed with statuscode: 404
# 多等一会，再观察pod的重启次数，发现一直是0，并未重启
[root@master ~]# kubectl get pods pod-restartpolicy -n dev
NAME READY STATUS RESTARTS AGE
pod-restartpolicy 1/1 Running 0 25s
[root@master ~]# kubectl get pods pod-restartpolicy -n dev
NAME READY STATUS RESTARTS AGE
pod-restartpolicy 0/1 Completed 0 44s六、pod调度
在默认情况下，一个Pod在哪个Node节点上运行，是由Scheduler组件采用相应的算法计算出来的，这个过程是不受人工控制的。但是在实际使用中，这并不满足的需求，因为很多情况下，我们想控制某些Pod到达某些节点上，那么应该怎么做呢？这就要求了解kubernetes对Pod的调度规则，kubernetes提供了四大类调度方式：
自动调度：运行在哪个节点上完全由Scheduler经过一系列的算法计算得出
定向调度：NodeName、NodeSelector
亲和性调度：NodeAffinity、PodAffinity、PodAntiAffinity
污点（容忍）调度：Taints、Toleration
1、定向调度
定向调度，指的是利用在pod上声明nodeName或者nodeSelector，以此将Pod调度到期望的node节点上。注意，这里的调度是强制的，这就意味着即使要调度的目标Node不存在，也会向上面进行调度，只不过pod运行失败而已。
1.1 NodeName
NodeName用于强制约束将Pod调度到指定的Name的Node节点上。这种方式，其实是直接跳过Scheduler的调度逻辑，直接将Pod调度到指定名称的节点。
（1）创建一个pod-nodename.yaml文件
powershell
[root@master ~]# cat pod-nodename.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-nodename
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
nodeName: node1 # 指定调度到node1节点上
[root@master ~]# kubectl apply -f pod-nodename.yaml
pod/pod-nodename created
#查看Pod调度到NODE属性，确实是调度到了node1节点上
[root@master ~]# kubectl get pods pod-nodename -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-nodename 1/1 Running 0 40s 172.16.166.154 node1 <none> <none>
# 接下来，删除pod，修改nodeName的值为node3（并没有node3节点）
[root@master ~]# kubectl delete -f pod-nodename.yaml
pod "pod-nodename" deleted
[root@master ~]# vim pod-nodename.yaml
[root@master ~]# cat pod-nodename.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-nodename
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
nodeName: node3
[root@master ~]# kubectl apply -f pod-nodename.yaml
pod/pod-nodename created
#再次查看，发现已经向Node3节点调度，但是由于不存在node3节点，所以pod无法正常运行
[root@master ~]# kubectl get pods pod-nodename -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-nodename 0/1 Pending 0 6s <none> node3 <none> <none>1.2 NodeSelector
NodeSelector用于将pod调度到添加了指定标签的node节点上。它是通过kubernetes的label-selector机制实现的，也就是说，在pod创建之前，会由scheduler使用MatchNodeSelector调度策略进行label匹配，找出目标node，然后将pod调度到目标节点，该匹配规则是强制约束。
（1）首先分别为node节点添加标签
powershell
[root@master ~]# kubectl label nodes node1 nodeenv=pro
node/node1 labeled
[root@master ~]# kubectl label nodes node2 nodeenv=test
node/node2 labeled（2）创建一个pod-nodeselector.yaml文件，并使用它创建Pod
powershell
[root@master ~]# vim pod-nodeselector.yaml
[root@master ~]# cat pod-nodeselector.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-nodeselector
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
nodeSelector:
nodeenv: pro # 指定调度到具有nodeenv=pro标签的节点上
[root@master ~]# kubectl apply -f pod-nodeselector.yaml
pod/pod-nodeselector created
#查看Pod调度到NODE属性，确实是调度到了node1节点上
[root@master ~]# kubectl get pods pod-nodeselector -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-nodeselector 1/1 Running 0 27s 172.16.166.155 node1 <none> <none>
# 接下来，删除pod，修改nodeSelector的值为nodeenv: xxxx（不存在打有此标签的节点）
[root@master ~]# kubectl delete -f pod-nodeselector.yaml
pod "pod-nodeselector" deleted
[root@master ~]# vim pod-nodeselector.yaml
[root@master ~]# cat pod-nodeselector.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-nodeselector
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
nodeSelector:
nodeenv: xxxx
[root@master ~]# kubectl apply -f pod-nodeselector.yaml
pod/pod-nodeselector created
#再次查看，发现pod无法正常运行,Node的值为none
[root@master ~]# kubectl get pods pod-nodeselector -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-nodeselector 0/1 Pending 0 7s <none> <none> <none> <none>
# 查看详情,发现node selector匹配失败的提示
[root@master ~]# kubectl describe pods pod-nodeselector -n dev
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedScheduling 31s default-scheduler 0/3 nodes are available: 1 node(s) had untolerated taint {node-role.kubernetes.io/control-plane: }, 2 node(s) didn't match Pod's node affinity/selector. preemption: 0/3 nodes are available: 3 Preemption is not helpful for scheduling..2、亲和性调度
上一节，介绍了两种定向调度的方式，使用起来非常方便，但是也有一定的问题，那就是如果没有满足条件的Node，那么Pod将不会被运行，即使在集群中还有可用Node列表也不行，这就限制了它的使用场景。
基于上面的问题，kubernetes还提供了一种亲和性调度（Affinity）。它在NodeSelector的基础之上的进行了扩展，可以通过配置的形式，实现优先选择满足条件的Node进行调度，如果没有，也可以调度到不满足条件的节点上，使调度更加灵活。
Affinity主要分为三类：
nodeAffinity(node亲和性）: 以node为目标，解决pod可以调度到哪些node的问题
podAffinity(pod亲和性) : 以pod为目标，解决pod可以和哪些已存在的pod部署在同一个拓扑域中的问题
podAntiAffinity(pod反亲和性) : 以pod为目标，解决pod不能和哪些已存在pod部署在同一个拓扑域中的问题
关于亲和性(反亲和性)使用场景的说明：
亲和性：如果两个应用频繁交互，那就有必要利用亲和性让两个应用的尽可能的靠近，这样可以减少因网络通信而带来的性能损耗。
反亲和性：当应用的采用多副本部署时，有必要采用反亲和性让各个应用实例打散分布在各个node上，这样可以提高服务的高可用性。
2.1 NodeAffinity
（1）首先来看一下NodeAffinity的可配置项
powershell
pod.spec.affinity.nodeAffinity
requiredDuringSchedulingIgnoredDuringExecution Node节点必须满足指定的所有规则才可以，相当于硬限制
nodeSelectorTerms 节点选择列表
matchFields 按节点字段列出的节点选择器要求列表
matchExpressions 按节点标签列出的节点选择器要求列表(推荐)
key 键
values 值
operator 关系符 支持Exists, DoesNotExist, In, NotIn, Gt, Lt
preferredDuringSchedulingIgnoredDuringExecution 优先调度到满足指定的规则的Node，相当于软限制 (倾向)
preference 一个节点选择器项，与相应的权重相关联
matchFields 按节点字段列出的节点选择器要求列表
matchExpressions 按节点标签列出的节点选择器要求列表(推荐)
key 键
values 值
operator 关系符 支持In, NotIn, Exists, DoesNotExist, Gt, Lt
weight 倾向权重，在范围1-100。
关系符的使用说明:
- matchExpressions:
- key: nodeenv # 匹配存在标签的key为nodeenv的节点
operator: Exists
- key: nodeenv # 匹配标签的key为nodeenv,且value是"xxx"或"yyy"的节点
operator: In
values: ["xxx","yyy"]
- key: nodeenv # 匹配标签的key为nodeenv,且value大于"xxx"的节点
operator: Gt
values: "xxx"requiredDuringSchedulingIgnoredDuringExecution（硬限制）
（1）创建pod-nodeaffinity-required.yaml
powershell
[root@master ~]# cat pod-nodeaffinity-required.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-nodeaffinity-required
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
affinity: #亲和性设置
nodeAffinity: #设置node亲和性
requiredDuringSchedulingIgnoredDuringExecution: # 硬限制
nodeSelectorTerms:
- matchExpressions: # 匹配env的值在["xxx","yyy"]中的标签
- key: nodeenv
operator: In
values: ["xxx","yyy"]
[root@master ~]# kubectl apply -f pod-nodeaffinity-required.yaml
pod/pod-nodeaffinity-required created
# 查看pod状态 （运行失败）
[root@master ~]# kubectl get pods pod-nodeaffinity-required -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-nodeaffinity-required 0/1 Pending 0 59s <none> <none> <none> <none>
# 查看Pod的详情# 发现调度失败，提示node选择失败
[root@master ~]# kubectl describe pod pod-nodeaffinity-required -n dev
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedScheduling 72s default-scheduler 0/3 nodes are available: 1 node(s) had untolerated taint {node-role.kubernetes.io/control-plane: }, 2 node(s) didn't match Pod's node affinity/selector. preemption: 0/3 nodes are available: 3 Preemption is not helpful for scheduling..
#接下来，停止pod
[root@master ~]# kubectl delete -f pod-nodeaffinity-required.yaml
pod "pod-nodeaffinity-required" deleted
# 修改文件，将values: ["xxx","yyy"]------> ["pro","yyy"]
[root@master ~]# vim pod-nodeaffinity-required.yaml
# 再次启动
[root@master ~]# kubectl apply -f pod-nodeaffinity-required.yaml
pod/pod-nodeaffinity-required created
# 此时查看，发现调度成功，已经将pod调度到了node1上
[root@master ~]# kubectl get pods pod-nodeaffinity-required -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-nodeaffinity-required 1/1 Running 0 7s 172.16.166.156 node1 <none> <none>preferredDuringSchedulingIgnoredDuringExecution（软限制）
（1）创建pod-nodeaffinity-preferred.yaml
powershell
[root@master ~]# cat pod-nodeaffinity-preferred.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-nodeaffinity-preferred
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
affinity: #亲和性设置
nodeAffinity: #设置node亲和性
preferredDuringSchedulingIgnoredDuringExecution: # 软限制
- weight: 1
preference:
matchExpressions: # 匹配env的值在["xxx","yyy"]中的标签(当前环境没有)
- key: nodeenv
operator: In
values: ["xxx","yyy"]
[root@master ~]# kubectl create -f pod-nodeaffinity-preferred.yaml
pod/pod-nodeaffinity-preferred created
# 查看pod状态 （运行成功）
[root@master ~]# kubectl get pod pod-nodeaffinity-preferred -n dev
NAME READY STATUS RESTARTS AGE
pod-nodeaffinity-preferred 1/1 Running 0 8s
[root@master ~]# kubectl get pod pod-nodeaffinity-preferred -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-nodeaffinity-preferred 1/1 Running 0 21s 172.16.104.30 node2 <none> <none>NodeAffinity规则设置的注意事项：
1、如果同时定义了nodeSelector和nodeAffinity，那么必须两个条件都得到满足，Pod才能运行在指定的Node上
2、如果nodeAffinity指定了多个nodeSelectorTerms，那么只需要其中一个能够匹配成功即可
3、如果一个nodeSelectorTerms中有多个matchExpressions ，则一个节点必须满足所有的才能匹配成功
4、如果一个pod所在的Node在Pod运行期间其标签发生了改变，不再符合该Pod的节点亲和性需求，则系统将忽略此变化
2.2 PodAffinity
PodAffinity主要实现以运行的Pod为参照，实现让新创建的Pod跟参照pod在一个区域的功能。
（1）PodAffinity的可配置项
powershell
pod.spec.affinity.podAffinity
requiredDuringSchedulingIgnoredDuringExecution 硬限制
namespaces 指定参照pod的namespace
topologyKey 指定调度作用域
labelSelector 标签选择器
matchExpressions 按节点标签列出的节点选择器要求列表(推荐)
key 键
values 值
operator 关系符 支持In, NotIn, Exists, DoesNotExist.
matchLabels 指多个matchExpressions映射的内容
preferredDuringSchedulingIgnoredDuringExecution 软限制
podAffinityTerm 选项
namespaces
topologyKey
labelSelector
matchExpressions
key 键
values 值
operator
matchLabels
weight 倾向权重，在范围1-100
topologyKey用于指定调度时作用域,例如:
如果指定为kubernetes.io/hostname，那就是以Node节点为区分范围
如果指定为beta.kubernetes.io/os,则以Node节点的操作系统类型来区分requiredDuringSchedulingIgnoredDuringExecution（硬限制）
（1）首先创建一个参照Pod，pod-podaffinity-target.yaml
powershell
[root@master ~]# vim pod-podaffinity-target.yaml
[root@master ~]# cat pod-podaffinity-target.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-podaffinity-target
namespace: dev
labels:
podenv: pro #设置标签
spec:
containers:
- name: nginx
image: nginx:1.17.1
nodeName: node1 # 将目标pod名确指定到node1上
[root@master ~]# kubectl create -f pod-podaffinity-target.yaml
pod/pod-podaffinity-target created
[root@master ~]# kubectl get pods pod-podaffinity-target -n dev
NAME READY STATUS RESTARTS AGE
pod-podaffinity-target 1/1 Running 0 10s（2）创建pod-podaffinity-required.yaml
powershell
[root@master ~]# vim pod-podaffinity-required.yaml
[root@master ~]# cat pod-podaffinity-required.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-podaffinity-required
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
affinity: #亲和性设置
podAffinity: #设置pod亲和性
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions: # 匹配env的值在["xxx","yyy"]中的标签
- key: podenv
operator: In
values: ["xxx","yyy"]
topologyKey: kubernetes.io/hostname
#上面配置表达的意思是：新Pod必须要与拥有标签nodeenv=xxx或者nodeenv=yyy的pod在同一Node上，显然现在没有这样pod，接下来，运行测试一下
[root@master ~]# kubectl create -f pod-podaffinity-required.yaml
pod/pod-podaffinity-required created
# 查看pod状态，发现未运行
[root@master ~]# kubectl get pods pod-podaffinity-required -n dev
NAME READY STATUS RESTARTS AGE
pod-podaffinity-required 0/1 Pending 0 10s
# 查看详细信息
[root@master ~]# kubectl describe pods pod-podaffinity-required -n dev
......
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedScheduling 22s default-scheduler 0/3 nodes are available: 1 node(s) had untolerated taint {node-role.kubernetes.io/control-plane: }, 2 node(s) didn't match pod affinity rules. preemption: 0/3 nodes are available: 3 Preemption is not helpful for scheduling..
# 接下来修改 values: ["xxx","yyy"]----->values:["pro","yyy"]# 意思是：新Pod必须要与拥有标签nodeenv=xxx或者nodeenv=yyy的pod在同一Node上
[root@master ~]# kubectl delete -f pod-podaffinity-required.yaml
pod "pod-podaffinity-required" deleted
[root@master ~]# vim pod-podaffinity-required.yaml
[root@master ~]# cat pod-podaffinity-required.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-podaffinity-required
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
affinity: #亲和性设置
podAffinity: #设置pod反亲和性
requiredDuringSchedulingIgnoredDuringExecution: # 硬限制
- labelSelector:
matchExpressions: # 匹配podenv的值在["pro"]中的标签
- key: podenv
operator: In
values: ["pro","yyy"]
topologyKey: kubernetes.io/hostname
[root@master ~]# kubectl apply -f pod-podaffinity-required.yaml
pod/pod-podaffinity-required created
[root@master ~]# kubectl get pods pod-podaffinity-required -n dev
NAME READY STATUS RESTARTS AGE
pod-podaffinity-required 1/1 Running 0 9sPodAntiAffinity
PodAntiAffinity主要实现以运行的Pod为参照，让新创建的Pod跟参照pod不在一个区域中的功能。
它的配置方式和选项跟PodAffinty是一样的，这里不再做详细解释，直接做一个测试案例
将上面的案例的亲和性改为反亲和性（将PodAffinity改为PodAntiAffinity）
powershell
[root@master ~]# cat pod-podaffinity-required.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-podaffinity-required
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: podenv
operator: In
values: ["pro","yyy"]
topologyKey: kubernetes.io/hostname
[root@master ~]# kubectl delete -f pod-podaffinity-required.yaml
pod "pod-podaffinity-required" deleted
[root@master ~]# kubectl apply -f pod-podaffinity-required.yaml
pod/pod-podaffinity-required created
# 查看pod
# 发现调度到了node2上
[root@master ~]# kubectl get pods pod-podaffinity-required -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-podaffinity-required 1/1 Running 0 12s 172.16.104.31 node2 <none> <none>上面配置表达的意思是：新Pod必须要与拥有标签nodeenv=pro的pod不在同一Node上。
七、污点和容忍
1、污点（Taints）
前面的调度方式都是站在Pod的角度上，通过在Pod上添加属性，来确定Pod是否要调度到指定的Node上，其实我们也可以站在Node的角度上，通过在Node上添加污点属性，来决定是否允许Pod调度过来。
Node被设置上污点之后就和Pod之间存在了一种相斥的关系，进而拒绝Pod调度进来，甚至可以将已经存在的Pod驱逐出去。
污点的格式为：key=value:effect, key和value是污点的标签，effect描述污点的作用，支持如下三个选项：
PreferNoSchedule：kubernetes将尽量避免把Pod调度到具有该污点的Node上，除非没有其他节点可调度
NoSchedule：kubernetes将不会把Pod调度到具有该污点的Node上，但不会影响当前Node上已存在的Pod
NoExecute：kubernetes将不会把Pod调度到具有该污点的Node上，同时也会将Node上已存在的Pod驱离
（1）使用kubectl设置和去除污点
powershell
# 设置污点
kubectl taint nodes node1 key=value:effect
# 去除污点
kubectl taint nodes node1 key:effect-
# 去除所有污点
kubectl taint nodes node1 key-2、演示下污点的效果
（1）准备节点node2（为了演示效果更加明显，暂时停止node1节点）
可直接将node2节点关机
powershell
[root@master ~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
master Ready control-plane 6d16h v1.28.15
node1 NotReady <none> 6d16h v1.28.15
node2 Ready <none> 6d16h v1.28.15（2） 为node2节点设置一个污点: tag=stw:PreferNoSchedule；然后创建pod1( pod1 可以 )
powershell
[root@master ~]# kubectl taint nodes node2 tag=stw:PreferNoSchedule
node/node2 tainted
[root@master ~]# kubectl run taint1 --image=nginx:1.17.1 -n dev
pod/taint1 created
[root@master ~]# kubectl get pods taint1 -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
taint1 1/1 Running 0 38s 172.16.104.38 node2 <none> <none>（3）修改为node2节点设置一个污点: tag=stw:NoSchedule；然后创建pod2( pod1 正常 pod2 失败 ，且node2节点的其余pod都正常)
powershell
[root@master ~]# kubectl taint nodes node2 tag:PreferNoSchedule-
node/node2 untainted
[root@master ~]# kubectl taint nodes node2 tag=stw:NoSchedule
node/node2 tainted
[root@master ~]# kubectl run taint2 --image=nginx:1.17.1 -n dev
pod/taint2 created
[root@master ~]# kubectl get pods taint2 -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
taint2 0/1 Pending 0 8s <none> <none> <none> <none>
[root@master ~]# kubectl get pods taint1 -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
taint1 1/1 Running 0 4m20s 172.16.104.38 node2 <none> <none>
[root@master ~]# kubectl get pods -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-6c45cbd8c5-2jgdb 1/1 Running 2 (37m ago) 3d22h 172.16.104.32 node2 <none> <none>
nginx-6c45cbd8c5-7cgpn 1/1 Running 0 4m47s 172.16.104.39 node2 <none> <none>
nginx-6c45cbd8c5-tz458 1/1 Running 2 (37m ago) 3d22h 172.16.104.37 node2 <none> <none>
nginx-6c45cbd8c5-vrmdw 1/1 Terminating 2 (37m ago) 3d22h 172.16.166.165 node1 <none> <none>
pod-hook-exec 1/1 Terminating 1 (37m ago) 16h 172.16.166.163 node1 <none> <none>
pod-initcontainer 1/1 Terminating 1 (37m ago) 16h 172.16.166.161 node1 <none> <none>
pod-liveness-exec 1/1 Running 1 (37m ago) 16h 172.16.104.33 node2 <none> <none>
pod-liveness-httpget 1/1 Terminating 1 (37m ago) 15h 172.16.166.160 node1 <none> <none>
pod-nodeaffinity-preferred 1/1 Running 1 (37m ago) 14h 172.16.104.36 node2 <none> <none>
pod-nodeaffinity-required 1/1 Terminating 1 (37m ago) 14h 172.16.166.162 node1 <none> <none>
pod-nodeselector 0/1 Pending 0 14h <none> <none> <none> <none>
pod-podaffinity-required 1/1 Running 1 (37m ago) 14h 172.16.104.35 node2 <none> <none>
pod-podaffinity-target 1/1 Terminating 1 (37m ago) 14h 172.16.166.164 node1 <none> <none>
taint1 1/1 Running 0 5m6s 172.16.104.38 node2 <none> <none>
taint2 0/1 Pending 0 102s <none> <none> <none> <none>（4）修改为node2节点设置一个污点: tag=stw:NoExecute；然后创建pod3 ( 3个pod都失败 ，即NoExecute不会让新创建的pod加入，并且会剔除已存在的pod)
powershell
[root@master ~]# kubectl taint nodes node2 tag:NoSchedule-
node/node2 untainted
[root@master ~]# kubectl taint nodes node2 tag=stw:NoExecute
node/node2 tainted
[root@master ~]# kubectl run taint3 --image=nginx:1.17.1 -n dev
pod/taint3 created
[root@master ~]# kubectl get pods taint1 -n dev -o wide
Error from server (NotFound): pods "taint1" not found
[root@master ~]# kubectl get pods taint2 -n dev -o wide
Error from server (NotFound): pods "taint2" not found
[root@master ~]# kubectl get pods taint3 -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
taint3 0/1 Pending 0 2m56s <none> <none> <none> <none>
[root@master ~]# kubectl get pods -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-6c45cbd8c5-gpn7z 0/1 Pending 0 34s <none> <none> <none> <none>
nginx-6c45cbd8c5-km7rw 0/1 Pending 0 34s <none> <none> <none> <none>
nginx-6c45cbd8c5-vrmdw 1/1 Terminating 2 (39m ago) 3d22h 172.16.166.165 node1 <none> <none>
nginx-6c45cbd8c5-wk6v4 0/1 Pending 0 34s <none> <none> <none> <none>
pod-hook-exec 1/1 Terminating 1 (39m ago) 16h 172.16.166.163 node1 <none> <none>
pod-initcontainer 1/1 Terminating 1 (39m ago) 16h 172.16.166.161 node1 <none> <none>
pod-liveness-httpget 1/1 Terminating 1 (39m ago) 15h 172.16.166.160 node1 <none> <none>
pod-nodeaffinity-required 1/1 Terminating 1 (39m ago) 14h 172.16.166.162 node1 <none> <none>
pod-nodeselector 0/1 Pending 0 14h <none> <none> <none> <none>
pod-podaffinity-target 1/1 Terminating 1 (39m ago) 14h 172.16.166.164 node1 <none> <none>
taint3 0/1 Pending 0 16s <none> <none> <none> <none>注意：使用kubeadm搭建的集群，默认就会给master节点添加一个污点标记,所以pod就不会调度到master节点上
2、容忍（Toleration）
上面介绍了污点的作用，我们可以在node上添加污点用于拒绝pod调度上来，但是如果就是想将一个pod调度到一个有污点的node上去，这时候应该怎么做呢？这就要使用到容忍。
污点就是拒绝，容忍就是忽略，Node通过污点拒绝pod调度上去，Pod通过容忍忽略拒绝
案例
1、上一小节，已经在node1节点上打上了NoExecute的污点，此时pod是调度不上去的
2、本小节，可以通过给pod添加容忍，然后将其调度上去
（1）创建pod-toleration.yaml
powershell
[root@master ~]# cat pod-toleration.yaml
apiVersion: v1
kind: Pod
metadata:
name: pod-toleration
namespace: dev
spec:
containers:
- name: nginx
image: nginx:1.17.1
tolerations: # 添加容忍
- key: "tag" # 要容忍的污点的key
operator: "Equal" # 操作符
value: "stw" # 容忍的污点的value
effect: "NoExecute" # 添加容忍的规则，这里必须和标记的污点规则相同
[root@master ~]# kubectl apply -f pod-toleration.yaml
pod/pod-toleration created
# 添加容忍的pod
[root@master ~]# kubectl get -f pod-toleration.yaml -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod-toleration 1/1 Running 0 9s 172.16.104.46 node2 <none> <none>
# 没有添加容忍的pod
[root@master ~]# kubectl run taint3 --image=nginx -n dev
pod/taint3 created
[root@master ~]# kubectl get pods taint3 -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
taint3 0/1 Pending 0 8s <none> <none> <none> <none>（2）容忍的详细配置
powershell
[root@master ~]# kubectl explain pod.spec.tolerations
......
FIELDS:
key # 对应着要容忍的污点的键，空意味着匹配所有的键
value # 对应着要容忍的污点的值
operator # key-value的运算符，支持Equal和Exists（默认）
effect # 对应污点的effect，空意味着匹配所有影响
tolerationSeconds # 容忍时间, 当effect为NoExecute时生效，表示pod在Node上的停留时间