Kubernetes学习目录
1、基础知识
1.1、简介
所谓的反亲和，其实就是满足条件的话，就离这个pod远远的，从此不见面。与亲和正好相反
1.2、属性解析
kubectl explain pod.spec.affinity.podAntiAffinity
requiredDuringSchedulingIgnoredDuringExecution -- 硬亲和性：
labelSelector 选择跟那组Pod亲和，前提得知道如何判断
namespaces 选择哪个命名空间进行条件匹配
topologyKey 指定节点上的哪个键，这是一个必选项
注意：这三个条件是一个逻辑与的关系
preferredDuringSchedulingIgnoredDuringExecution -- 软亲和性：
podAffinityTerm 与权重关联的亲和选项，这是一个必选项
labelSelector 标签选择器
namespaces 命令空间名称
topologyKey 指定节点上的哪个键，这是一个必选项
weight 权重，这是一个必选项
注意：Pod反亲和性场景，当应用服务A和数据库服务B要求尽量不要在同一台节点上的时候。
2、Pod调度之反亲和性-podAntiAffinity-实践
2.1、硬反亲和性-实践
2.1.1、需求
不要跟包含有标签env=dev运行的pod，放在一起
2.1.2、给节点打标签【用于给env运行pod分开调度节点】
kubectl label node node2 env=test
kubectl label node node1 env=dev
2.1.3、创建env=test、env=dev的运行pod
kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
name: pod-dev
labels:
env: dev
spec:
containers:
- name: pod-test
image: 192.168.10.33:80/k8s/pod_test:v0.1
imagePullPolicy: IfNotPresent
nodeSelector:
env: dev
---
apiVersion: v1
kind: Pod
metadata:
name: pod-test
labels:
env: test
spec:
containers:
- name: pod-test
image: 192.168.10.33:80/k8s/pod_test:v0.1
imagePullPolicy: IfNotPresent
nodeSelector:
env: test
EOF
# 该pod的调度策略，env: test调度到node2，env: dev调度到node1
2.1.4、查询标签env运行的pod是否被分别调度到不同节点上
master1 ~]# kubectl get pods -o wide --show-labels
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES LABELS
pod-dev 1/1 Running 0 8s 10.244.3.63 node1 <none> <none> env=dev
pod-test 1/1 Running 0 8s 10.244.4.93 node2 <none> <none> env=test
2.1.5、定义资源配置清单且应用【场景：强制不往标签env=dev运行pod的节点上调度】
kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
name: pod-antiaffinity
spec:
containers:
- name: pod-test
image: 192.168.10.33:80/k8s/pod_test:v0.1
imagePullPolicy: IfNotPresent
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- {key: env, operator: In, values: ["dev"]}
topologyKey: kubernetes.io/hostname
EOF
2.1.6、查询调度的结果
master1 ~]# kubectl get pods -o wide --show-labels
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES LABELS
pod-antiaffinity 1/1 Running 0 4s 10.244.4.94 node2 <none> <none> <none>
pod-dev 1/1 Running 0 4m41s 10.244.3.63 node1 <none> <none> env=dev
pod-test 1/1 Running 0 4m41s 10.244.4.93 node2 <none> <none> env=test
总结：
因为排它条件env=dev,所以不会调度跟运行pod标签带有env=dev相同的节点上
2.2、软反亲和性-实践
2.2.1、需求
最好不要哪些pod放在一起，使用给标签设置权重，按权重调度最佳节
2.2.2、设置标签
kubectl label node node2 env=test
kubectl label node node1 env=dev
2.2.3、创建env=test、env=dev的运行pod
创建方法请查看： 2.1.2、创建env=test、env=dev的运行pod
2.2.4、查询标签env运行的pod是否被分别调度到不同节点上
master1 ~]# kubectl get pods -o wide --show-labels
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES LABELS
pod-dev 1/1 Running 0 8s 10.244.3.63 node1 <none> <none> env=dev
pod-test 1/1 Running 0 8s 10.244.4.93 node2 <none> <none> env=test
2.2.5、定义资源配置清单且应用【场景：不往标签权重最高的env=dev运行pod的节点上调度】
kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
name: pod-antiaffinity
spec:
containers:
- name: pod-test
image: 192.168.10.33:80/k8s/pod_test:v0.1
imagePullPolicy: IfNotPresent
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- weight: 100
podAffinityTerm:
labelSelector:
matchExpressions:
- {key: env, operator: In, values: ["dev"]}
topologyKey: kubernetes.io/hostname
- weight: 50
podAffinityTerm:
labelSelector:
matchExpressions:
- {key: env, operator: In, values: ["test"]}
topologyKey: kubernetes.io/hostname
EOF
2.2.6、查询调度的结果
master1 ~]# kubectl get pods -o wide --show-labels
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES LABELS
pod-antiaffinity 1/1 Running 0 2s 10.244.4.95 node2 <none> <none> <none>
pod-dev 1/1 Running 0 12m 10.244.3.63 node1 <none> <none> env=dev
pod-test 1/1 Running 0 12m 10.244.4.93 node2 <none> <none> env=test
总结：
因为是反亲和性，dev的权重最高，所以不往dev调度
3、为什么没有node反亲和性-nodeAntiAffinity
affinity.nodeAffinity.nodeSelectorTerms.matchExpressions.operator
操作符
NotIn：标签的值不在某个列表中
DoesNotExist：某个标签不存在
因为NotIn和DoesNotExist可以提供相同的功能。
