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Kubernetes 污点、容忍策略、优先级与抢占、Pod安全

污点

污点使结点与pod产生排斥与标签相反

污点策略是通过嵌入合在键值对上的污点标签进行声明

污点标签必须绑定在键值对上，格式为：key=value:[污点标签]

taint翻译就是污点的意思

污点标签必须绑定在键值对上，格式为：key=value:[污点标签]

查看污点标签

    kubectl describe nodes [结点名]

设置污点标签

    kubectl taint node [结点名字] key=value:污点标签

删除污点标签

    kubectl taint node [结点名字] key=value:污点标签-

污点标签

结点的调度是需要schedule筛选、打分的

    PreferNoSchedule尽量不调度，只要不剩它一个就不被调度

    NoSchedule不调度，筛选都进不去

    NoExecute驱逐结点

PreferNoSchedule 、NoSchedule这两个只对新建的pod有效.

NoExecute对之前之后的pod都有效，删除、

管理污点标签

# 查看污点策略
[root@master ~]# kubectl describe nodes|grep Taints
Taints:             node-role.kubernetes.io/master:NoSchedule
Taints:             <none>
Taints:             <none>
Taints:             <none>

# node-0001 设置污点策略 PreferNoSchedule
[root@master ~]# kubectl taint node node-0001 k1=v1:PreferNoSchedule
node/node-0001 tainted
# node-0002 设置污点策略 NoSchedule
[root@master ~]# kubectl taint node node-0002 k2=v2:NoSchedule
node/node-0002 tainted

[root@master ~]# kubectl describe nodes |grep Taints
Taints:             node-role.kubernetes.io/master:NoSchedule
Taints:             k1=v1:PreferNoSchedule
Taints:             k2=v2:NoSchedule
Taints:             <none>

Pod资源文件

# 查看污点策略
[root@master ~]# kubectl describe nodes|grep Taints
Taints:             node-role.kubernetes.io/master:NoSchedule
Taints:             <none>
Taints:             <none>
Taints:             <none>

# node-0001 设置污点策略 PreferNoSchedule
[root@master ~]# kubectl taint node node-0001 k1=v1:PreferNoSchedule
node/node-0001 tainted
# node-0002 设置污点策略 NoSchedule
[root@master ~]# kubectl taint node node-0002 k2=v2:NoSchedule
node/node-0002 tainted

[root@master ~]# kubectl describe nodes |grep Taints
Taints:             node-role.kubernetes.io/master:NoSchedule
Taints:             k1=v1:PreferNoSchedule
Taints:             k2=v2:NoSchedule
Taints:             <none>

验证污点策略

# 优先使用没有污点的节点
[root@master ~]# sed "s,myphp,php1," myphp.yaml |kubectl apply -f -
pod/php1 created
[root@master ~]# sed "s,myphp,php2," myphp.yaml |kubectl apply -f -
pod/php2 created
[root@master ~]# kubectl get pods -o wide
NAME   READY   STATUS    RESTARTS   AGE   IP            NODE
php1   1/1     Running   0          13s   10.244.3.43   node-0003
php2   1/1     Running   0          5s    10.244.3.44   node-0003

# 最后使用 PreferNoSchedule 节点
[root@master ~]# sed 's,myphp,php3,' myphp.yaml |kubectl apply -f -
pod/php3 created
[root@master ~]# sed 's,myphp,php4,' myphp.yaml |kubectl apply -f -
pod/php4 created
[root@master ~]# kubectl get pods -o wide
NAME   READY   STATUS    RESTARTS   AGE     IP            NODE
php1   1/1     Running   0          3m16s   10.244.3.43   node-0003
php2   1/1     Running   0          3m8s    10.244.3.44   node-0003
php3   1/1     Running   0          113s    10.244.1.8    node-0001
php4   1/1     Running   0          9s      10.244.1.9    node-0001

# 不会使用 NoSchedule 节点
[root@master ~]# sed 's,myphp,php5,' myphp.yaml |kubectl apply -f -
pod/php5 created
[root@master ~]# kubectl get pods -o wide
NAME   READY   STATUS    RESTARTS   AGE     IP            NODE
php1   1/1     Running   0          3m16s   10.244.3.43   node-0003
php2   1/1     Running   0          3m8s    10.244.3.44   node-0003
php3   1/1     Running   0          113s    10.244.1.8    node-0001
php4   1/1     Running   0          9s      10.244.1.9    node-0001
php5   0/1     Pending   0          5s      <none>        <none>

验证驱逐策略

[root@master ~]# kubectl taint node node-0003 k3=v3:NoExecute
node/node-0003 tainted
[root@master ~]# kubectl describe nodes |grep Taints
Taints:             node-role.kubernetes.io/master:NoSchedule
Taints:             k1=v1:PreferNoSchedule
Taints:             k2=v2:NoSchedule
Taints:             k3=v3:NoExecute
[root@master ~]# kubectl get pods -o wide
NAME   READY   STATUS    RESTARTS   AGE     IP           NODE
php3   1/1     Running   0          4m19s   10.244.1.8   node-0001
php4   1/1     Running   0          2m35s   10.244.1.9   node-0001
php5   0/1     Pending   0          2m31s   <none>       <none>

清理配置

[root@master ~]# kubectl delete pod php{3..5}
pod "php3" deleted
pod "php4" deleted
pod "php5" deleted
[root@master ~]# kubectl taint node node-0001 k1=v1:PreferNoSchedule-
node/node-0001 untainted
[root@master ~]# kubectl taint node node-0002 k2=v2:NoSchedule-
node/node-0002 untainted
[root@master ~]# kubectl taint node node-0003 k3=v3:NoExecute-
node/node-0003 untainted
[root@master ~]# kubectl describe nodes |grep Taints
Taints:             node-role.kubernetes.io/master:NoSchedule
Taints:             <none>
Taints:             <none>
Taints:             <none>

容忍策略

一般根据标签去做，所以必须绑定标签

容忍策略是什么，刚好与污点相反，某些时候我们就是要在有污点的节点上运行Pod，这种无视污点标签的调度方式称为容忍

为node设置污点

# 节点 node-0001 设置污点标签 k=v1:NoSchedule
[root@master ~]# kubectl taint node node-0001 k=v1:NoSchedule
node/node-0001 tainted

# 节点 node-0002 设置污点标签 k=v2:NoSchedule
[root@master ~]# kubectl taint node node-0002 k=v2:NoSchedule
node/node-0002 tainted

# 节点 node-0003 设置污点标签 k=v1:NoExecute
[root@master ~]# kubectl taint node node-0003 k=v1:NoExecute
node/node-0003 tainted

[root@master ~]# kubectl describe nodes |grep Taints
Taints:             node-role.kubernetes.io/master:NoSchedule
Taints:             k=v1:NoSchedule
Taints:             k=v2:NoSchedule
Taints:             k=v1:NoExecute

精确匹配（Equal）

精确匹配策略

# 容忍 k=v1:NoSchedule 污点
[root@master ~]# vim myphp.yaml
---
kind: Pod
apiVersion: v1
metadata:
  name: myphp
spec:
  tolerations:
  - operator: "Equal"      # 完全匹配键值对
    key: "k"               # 键
    value: "v1"            # 值
    effect: "NoSchedule"   # 污点标签
  containers:
  - name: php
    image: myos:phpfpm
    resources:
      requests:
        cpu: 800m

[root@master ~]# for i in php{1..3};do sed "s,myphp,${i}," myphp.yaml ;done|kubectl apply -f -
pod/php1 created
pod/php2 created
pod/php3 created
[root@master ~]# kubectl get pods -o wide
NAME   READY   STATUS    RESTARTS   AGE   IP            NODE
php1   1/1     Running   0          6s    10.244.1.10   node-0001
php2   1/1     Running   0          6s    10.244.1.11   node-0001
php3   1/1     Pending   0          6s    <none>        <none>
[root@master ~]# kubectl delete pod php{1..3}
pod "php1" deleted
pod "php2" deleted
pod "php3" deleted

模糊匹配（Exists）

模糊匹配策略

# 容忍 k=*:NoSchedule 污点
[root@master ~]# vim myphp.yaml
---
kind: Pod
apiVersion: v1
metadata:
  name: myphp
spec:
  tolerations:
  - operator: "Exists"     # 部分匹配，存在即可
    key: "k"               # 键
    effect: "NoSchedule"   # 污点标签
  containers:
  - name: php
    image: myos:phpfpm
    resources:
      requests:
        cpu: 800m

[root@master ~]# for i in php{1..3};do sed "s,myphp,${i}," myphp.yaml ;done|kubectl apply -f -
pod/php1 created
pod/php2 created
pod/php3 created
[root@master ~]# kubectl get pods -o wide
NAME   READY   STATUS    RESTARTS   AGE   IP            NODE
php1   1/1     Running   0          6s    10.244.1.12   node-0001
php2   1/1     Running   0          6s    10.244.2.21   node-0002
php3   1/1     Running   0          6s    10.244.2.22   node-0002
[root@master ~]# kubectl delete pod php{1..3}
pod "php1" deleted
pod "php2" deleted
pod "php3" deleted

所有污点标签

# 容忍所有 node 上的污点
[root@master ~]# vim myphp.yaml 
---
kind: Pod
apiVersion: v1
metadata:
  name: myphp
spec:
  tolerations:
  - operator: "Exists"     # 模糊匹配
    key: "k"               # 键
    effect:                # 没有设置污点标签代表所有
  containers:
  - name: php
    image: myos:phpfpm
    resources:
      requests:
        cpu: 800m

[root@master ~]# for i in php{1..3};do sed "s,myphp,${i}," myphp.yaml ;done|kubectl apply -f -
pod/php1 created
pod/php2 created
pod/php3 created
[root@master ~]# kubectl get pods -o wide
NAME   READY   STATUS    RESTARTS   AGE   IP            NODE
php1   1/1     Running   0          36s   10.244.1.15   node-0001
php2   1/1     Running   0          36s   10.244.2.16   node-0002
php3   1/1     Running   0          36s   10.244.3.18   node-0003
[root@master ~]# kubectl delete pod php{1..3}
pod "php1" deleted
pod "php2" deleted
pod "php3" deleted

抢占与优先级

优先级表示一个Pod相对于其他Pod的重要性

优先级可以保证重要的Pod被调度运行

当资源比较紧张才用优先级

如何使用优先级和抢占

配置优先级类PriorityClass

创建Pod时为其设置对应的优先级

优先级概述

PriorityClass是一个全局资源对象，定义了从优先级类名称到优先级整数值的映射。优先级在value字段中指定，可以设置小于10亿的整数值，值越大，优先级越高。

PriorityClass还有两个可选字段：

    -globalDefault用于设置默认优先级状态，如果没有任何优先级设置Pod的优先级为零

    -description用来配置描述性信息，告诉用户优先级的用途

优先级概述

优先级策略：

    非抢占优先(插队)：在调度阶段优先进行调度分配，一旦容器调度完成就不可抢占，资源不足时，只能等待，

    抢占优先(杀死)：强制调度一个pod，如果资源不足无法被调度，调度程序会抢占（删除）较低优先级的Pod的资源，来保证高优先级Pod的运行

非抢占优先级

preemptionPolicy: Never #非抢占
value: 500 #值
description: non-preemptive #描述

# 定义优先级（队列优先）
[root@master ~]# vim mypriority.yaml
---
kind: PriorityClass
apiVersion: scheduling.k8s.io/v1
metadata:
  name: high-non
globalDefault: false
preemptionPolicy: Never
value: 1000
description: non-preemptive

---
kind: PriorityClass
apiVersion: scheduling.k8s.io/v1
metadata:
  name: low-non
globalDefault: false
preemptionPolicy: Never
value: 500
description: non-preemptive

[root@master ~]# kubectl apply -f mypriority.yaml 
priorityclass.scheduling.k8s.io/high-non created
priorityclass.scheduling.k8s.io/low-non created
[root@master ~]# kubectl get priorityclasses.scheduling.k8s.io 
NAME                      VALUE        GLOBAL-DEFAULT   AGE
high-non                  1000         false            12s
low-non                   500          false            12s
system-cluster-critical   2000000000   false            45h
system-node-critical      2000001000   false            45h

pod无，中，高优先级配置

# 无优先级的 Pod
[root@master ~]# cat php1.yaml 
---
kind: Pod
apiVersion: v1
metadata:
  name: php1
spec:
  nodeSelector:
    kubernetes.io/hostname: node-0002
  containers:
  - name: php
    image: myos:phpfpm
    resources:
      requests:
        cpu: "1500m"

# 低优先级 Pod
[root@master ~]# cat php2.yaml 
---
kind: Pod
apiVersion: v1
metadata:
  name: php2
spec:
  nodeSelector:
    kubernetes.io/hostname: node-0002
  priorityClassName: low-non      # 优先级名称
  containers:
  - name: php
    image: myos:phpfpm
    resources:
      requests:
        cpu: "1500m"

# 高优先级 Pod
[root@master ~]# cat php3.yaml 
---
kind: Pod
apiVersion: v1
metadata:
  name: php3
spec:
  nodeSelector:
    kubernetes.io/hostname: node-0002
  priorityClassName: high-non     # 优先级名称
  containers:
  - name: php
    image: myos:phpfpm
    resources:
      requests:
        cpu: "1500m"

验证非抢占优先

[root@master ~]# kubectl apply -f php1.yaml 
pod/php1 created
[root@master ~]# kubectl apply -f php2.yaml 
pod/php2 created
[root@master ~]# kubectl apply -f php3.yaml 
pod/php3 created
[root@master ~]# kubectl get pods
NAME   READY   STATUS    RESTARTS   AGE
php1   1/1     Running   0          9s
php2   0/1     Pending   0          6s
php3   0/1     Pending   0          4s
[root@master ~]# kubectl delete pod php1
pod "php1" deleted
[root@master ~]# kubectl get pods
NAME   READY   STATUS    RESTARTS   AGE
php2   0/1     Pending   0          20s
php3   1/1     Running   0          18s

# 清理实验 Pod
[root@master ~]# kubectl delete pod php2 php3
pod "php2" deleted
pod "php3" deleted

抢占策略

[root@master ~]# vim mypriority.yaml
---
kind: PriorityClass
apiVersion: scheduling.k8s.io/v1
metadata:
  name: high
globalDefault: false
preemptionPolicy: PreemptLowerPriority
value: 1000
description: non-preemptive

---
kind: PriorityClass
apiVersion: scheduling.k8s.io/v1
metadata:
  name: low
globalDefault: false
preemptionPolicy: PreemptLowerPriority
value: 500
description: non-preemptive

[root@master ~]# kubectl apply -f mypriority.yaml 
priorityclass.scheduling.k8s.io/high created
priorityclass.scheduling.k8s.io/low created
[root@master ~]# kubectl get priorityclasses.scheduling.k8s.io 
NAME                      VALUE        GLOBAL-DEFAULT   AGE
high                      1000         false            12s
low                       500          false            12s
system-cluster-critical   2000000000   false            45h
system-node-critical      2000001000   false            45h

验证抢占策略

# 默认优先级 Pod
[root@master ~]# kubectl apply -f php1.yaml 
pod/php1 created
[root@master ~]# kubectl get pods
NAME   READY   STATUS    RESTARTS   AGE
php1   1/1     Running   0          6s

# 高优先级 Pod
[root@master ~]# sed 's,-non,,' php3.yaml |kubectl apply -f - 
pod/php3 created
[root@master ~]# kubectl get pods
NAME   READY   STATUS    RESTARTS   AGE
php3   1/1     Running   0          9s

# 低优先级 Pod
[root@master ~]# sed 's,-non,,' php2.yaml |kubectl apply -f - 
pod/php2 created
[root@master ~]# kubectl get pods
NAME   READY   STATUS    RESTARTS   AGE
php2   0/1     Pending   0          3s
php3   1/1     Running   0          9s

# 清理实验 Pod
[root@master ~]# kubectl delete pod php2 php3
pod "php2" deleted
pod "php3" deleted
[root@master ~]# kubectl delete -f mypriority.yaml 
priorityclass.scheduling.k8s.io "high-non" deleted
priorityclass.scheduling.k8s.io "low-non" deleted
priorityclass.scheduling.k8s.io "high" deleted
priorityclass.scheduling.k8s.io "low" deleted

总结：有非抢占只是插队看优先级查，非抢占只是把当前运行的杀了，然后看优先级，低了你就想杀也杀不了 pod安全

特权容器

容器是通过名称空间技术隔离的，但是有时候我们需要突破隔离限制，获取更高的权限，这类容器称为特权容器

运行特权容器有风险

安全性

Pod安全策略是集群级别的资源，它能够控制Pod运行的行为，以及它具有访问什么的能力。

使用Pod安全策略服务器版本必须不低于版本v1,22

确保PodSecurity

apiServer是系统核心服务，如果出现故障，K8s将无法管理和维护，在修改之前备份资源文件

Pod安全策略

privileged 不受限制

baseline 弱限制性，禁止已知的策略提升权限

restricted 非常严格的限制性策略，遵循当前的保护Pod的最佳实践

Pod准入控制标签（MODE）

enforce 策略违例会导致Pod被拒绝

audit 策略违例会触发审计日志，但是Pod仍可以被接受

warn 策略违例会触发用户可见的警告信息，但是Pod仍然是被接受的

特权容器

更改容器主机名 和 /etc/hosts 文件

[root@master ~]# vim root.yaml
---
kind: Pod
apiVersion: v1
metadata:
  name: root
spec:
  terminationGracePeriodSeconds: 0
  restartPolicy: Always
  hostname: myhost         # 特权，修改主机名
  hostAliases:             # 修改 /etc/hosts
  - ip: 192.168.1.30       # IP 地址
    hostnames:             # 名称键值对
    - registry             # 主机名
  containers:
  - name: linux
    image: myos:v2009
    imagePullPolicy: IfNotPresent
    command: ["/bin/bash"]
    args:
    - -c
    - |
      while true;do
            echo "Hello World."
            sleep 5
      done

[root@master ~]# kubectl apply -f root.yaml 
pod/root created
[root@master ~]# kubectl exec -it root -- /bin/bash
[root@myhost html]# hostname
myhost
[root@myhost html]# cat /etc/hosts
... ...
# Entries added by HostAliases.
192.168.1.30    registry

[root@master ~]# kubectl delete pod root 
pod "root" deleted

root特权容器

[root@master ~]# vim root.yaml
---
kind: Pod
apiVersion: v1
metadata:
  name: root
spec:
  terminationGracePeriodSeconds: 0
  restartPolicy: Always
  hostPID: true            # 特权，共享系统进程
  hostNetwork: true        # 特权，共享主机网络
  containers:
  - name: linux
    image: myos:v2009
    imagePullPolicy: IfNotPresent
    securityContext:       # 安全上下文值
      privileged: true     # root特权容器
    command: ["/bin/bash"]
    args:
    - -c
    - |
      while true;do
            echo "Hello World."
            sleep 5
      done

[root@master ~]# kubectl get pods
NAME   READY   STATUS    RESTARTS   AGE
root   1/1     Running   0          26s
[root@master ~]# kubectl exec -it root -- /bin/bash
[root@node-0001 /]# 

# 系统进程特权
[root@node-0001 /]# pstree -p
systemd(1)-+-NetworkManager(510)-+-dhclient(548)
           |                     |-{NetworkManager}(522)
           |                     `-{NetworkManager}(524)
           |-agetty(851)
           |-chronyd(502)
           |-containerd(531)-+-{containerd}(555)
           ... ...

# 网络特权
[root@node-0001 /]# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.51  netmask 255.255.255.0  broadcast 192.168.1.255
        ether fa:16:3e:70:c8:fa  txqueuelen 1000  (Ethernet)
        ... ...

# root用户特权
[root@node-0001 /]# mkdir /sysroot
[root@node-0001 /]# mount /dev/sda1 /sysroot
[root@node-0001 /]# chroot /sysroot
sh-4.2# mount -t proc proc /proc
sh-4.2# : 此处已经是 node 节点上的 root 用户了

# 删除特权容器
[root@master ~]# kubectl delete pod root 
pod "root" deleted

Pod安全策略

[root@master ~]# sed '36i\    - --feature-gates=PodSecurity=true' -i /etc/kubernetes/manifests/kube-apiserver.yaml
[root@master ~]# systemctl restart kubelet

# 生产环境设置严格的准入控制
[root@master ~]# kubectl create namespace myprod
namespace/myprod created
[root@master ~]# kubectl label namespaces myprod pod-security.kubernetes.io/enforce=restricted
namespace/myprod labeled

# 测试环境测试警告提示
[root@master ~]# kubectl create namespace mytest
namespace/mytest created
[root@master ~]# kubectl label namespaces mytest pod-security.kubernetes.io/warn=baseline
namespace/mytest labeled

# 创建特权容器
[root@master ~]# kubectl -n myprod apply -f root.yaml 
Error from server (Failure): error when creating "root.yaml": host namespaces (hostNetwork=true, hostPID=true), privileged (container "linux" must not set securityContext.privileged=true), allowPrivilegeEscalation != false (container "linux" must set securityContext.allowPrivilegeEscalation=false), unrestricted capabilities (container "linux" must set securityContext.capabilities.drop=["ALL"]), runAsNonRoot != true (pod or container "linux" must set securityContext.runAsNonRoot=true), seccompProfile (pod or container "linux" must set securityContext.seccompProfile.type to "RuntimeDefault" or "Localhost")
[root@master ~]# 
[root@master ~]# kubectl -n myprod get pods
No resources found in myprod namespace.

[root@master ~]# kubectl -n mytest apply -f root.yaml                                    
Warning: would violate "latest" version of "baseline" PodSecurity profile: host namespaces (hostNetwork=true, hostPID=true), privileged (container "linux" must not set securityContext.privileged=true)
pod/root created
[root@master ~]# 
[root@master ~]# kubectl -n mytest get pods               
NAME   READY   STATUS    RESTARTS   AGE
root   1/1     Running   0          7s
[root@master ~]#

符合安全规则的Pod

[root@master ~]# vim nonroot.yaml
---
kind: Pod
apiVersion: v1
metadata:
  name: nonroot
spec:
  terminationGracePeriodSeconds: 0
  restartPolicy: Always
  containers:
  - name: linux
    image: myos:v2009
    imagePullPolicy: IfNotPresent
    securityContext:
      allowPrivilegeEscalation: false
      runAsNonRoot: true
      runAsUser: 99
      seccompProfile:
        type: "RuntimeDefault"
      capabilities:
        drop: ["ALL"]
    command: ["/bin/bash"]
    args:
    - -c
    - |
      while true;do
            echo "Hello World."
            sleep 30
      done

[root@master ~]# kubectl -n myprod apply -f nonroot.yaml 
pod/nonroot created
[root@master ~]# kubectl -n myprod get pods
NAME      READY   STATUS    RESTARTS   AGE
nonroot   1/1     Running   0          6s
[root@master ~]# kubectl -n myprod exec -it nonroot -- id
uid=99(nobody) gid=99(nobody) groups=99(nobody)
标签： kubernetes 容器 云原生
本文转载自: https://blog.csdn.net/weixin_55000003/article/details/130373981
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