概述:
- 先来理解 topology key 字段
pod亲和性调度须要各个相干的pod对象运行于"同一地位"， 而反亲和性调度则要求他们不能运行于"同一地位"，
这里指定“同一地位” 是通过 topologyKey 来定义的，topologyKey 对应的值是 node 上的一个标签名称，比方各别节点zone=A标签，各别节点有zone=B标签，pod affinity topologyKey定义为zone，那么调度pod的时候就会围绕着A拓扑，B拓扑来调度，而雷同拓扑下的node就为“同一地位”。 - 顾名思义，topology 就是 拓扑的意思
这里指的是一个 拓扑域，是指一个范畴的概念，比方一个 Node、一个机柜、一个机房或者是一个地区（如杭州、上海）等，实际上对应的还是 Node 上的标签。这里的 topologyKey 对应的是 Node 上的标签的 Key（没有Value），能够看出，其实 topologyKey 就是用于筛选 Node 的。通过这种形式，咱们就能够将各个 Pod 进行跨集群、跨机房、跨地区的调度了。
查看 podAffinity的具体阐明
[root@k8s-master Scheduler]# kubectl explain pods.spec.affinityKIND: PodVERSION: v1RESOURCE: affinity <Object>DESCRIPTION: If specified, the pod's scheduling constraints Affinity is a group of affinity scheduling rules.FIELDS: nodeAffinity <Object> #节点亲和 Describes node affinity scheduling rules for the pod. podAffinity <Object> #Pod亲和 Describes pod affinity scheduling rules (e.g. co-locate this pod in the same node, zone, etc. as some other pod(s)). podAntiAffinity <Object> #Pod反亲和 Describes pod anti-affinity scheduling rules (e.g. avoid putting this pod in the same node, zone, etc. as some other pod(s)). #亲和与反亲和中又分硬亲和 软亲和前一节提到的Node亲和一样不在累述[root@k8s-master Scheduler]# kubectl explain pods.spec.affinity.podAffinity FIELDS: preferredDuringSchedulingIgnoredDuringExecution <[]Object>... requiredDuringSchedulingIgnoredDuringExecution <[]Object>...#Pod反亲和[root@k8s-master Scheduler]# kubectl explain pods.spec.affinity.podAntiAffinityFIELDS: preferredDuringSchedulingIgnoredDuringExecution <[]Object>...ffinityTerm; the node(s) with the highest sum are the most preferred. requiredDuringSchedulingIgnoredDuringExecution <[]Object>...[root@k8s-master Scheduler]# kubectl explain pods.spec.affinity.podAntiAffinity.requiredDuringSchedulingIgnoredDuringExecution labelSelector <Object> A label query over a set of resources, in this case pods. namespaces <[]string> namespaces specifies which namespaces the labelSelector applies to (matches against); null or empty list means "this pod's namespace" topologyKey <string> -required- #拓扑标签 应用哪一个标签为地位标签(必选字段) This pod should be co-located (affinity) or not co-located (anti-affinity) with the pods matching the labelSelector in the specified namespaces, where co-located is defined as running on a node whose value of the label with key topologyKey matches that of any node on which any of the selected pods is running. Empty topologyKey is not allowed.示例1: podAffinity Pod硬亲和
requiredDuringSchedulingIgnoredDuringExecution
[root@k8s-master Scheduler]# cat pod-affinity-required-demo.yaml apiVersion: apps/v1kind: Deploymentmetadata: name: redis spec: replicas: 1 #redis为有状态利用 为了测试只运行1个正本 selector: matchLabels: app: redis ctlr: redis template: metadata: labels: app: redis ctlr: redis spec: containers: - name: redis image: redis:6.0-alpine---apiVersion: apps/v1kind: Deploymentmetadata: name: pod-affinity-requiredspec: replicas: 5 selector: matchLabels: app: demoapp ctlr: pod-affinity-required template: metadata: labels: app: demoapp ctlr: pod-affinity-required spec: containers: - name: demoapp image: ikubernetes/demoapp:v1.0 affinity: podAffinity: #Pod亲和 requiredDuringSchedulingIgnoredDuringExecution: #硬亲和 - labelSelector: matchExpressions: - {key: app, operator: In, values: ["redis"]} #简单示意达匹配标签 app=reids、ctlr=redis - {key: ctlr, operator: In, values: ["redis"]} #两个表达式为与关系 同时满足 topologyKey: rack #节点标签 地位标签 rack能够了解为同一个机架上 与labelSelector同样是与关系同时满足[root@k8s-master Scheduler]# kubectl apply -f pod-affinity-required-demo.yaml deployment.apps/redis unchangeddeployment.apps/pod-affinity-required unchanged[root@k8s-master Scheduler]# kubectl get pod -o wide #节点还没有打上标签pod-affinity挂机NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATESpod-affinity-required-5dd44f5d45-6vvhd 0/1 Pending 0 6m7s <none> <none> <none> <none>pod-affinity-required-5dd44f5d45-c4hzl 0/1 Pending 0 6m7s <none> <none> <none> <none>pod-affinity-required-5dd44f5d45-qm6zb 0/1 Pending 0 6m7s <none> <none> <none> <none>pod-affinity-required-5dd44f5d45-t4mm5 0/1 Pending 0 6m7s <none> <none> <none> <none>pod-affinity-required-5dd44f5d45-vs7dg 0/1 Pending 0 6m7s <none> <none> <none> <none>redis-55f46d9795-r7pkz 1/1 Running 0 10m 192.168.51.23 k8s-node3 <none> <none>- 模仿同一机架不同节点
[root@k8s-master Scheduler]# kubectl label node k8s-node1 rack=foo #为节点1把rack标签node/k8s-node1 labeled[root@k8s-master Scheduler]# kubectl label node k8s-node2 rack=bar #为节点2把rack标签node/k8s-node2 labeled[root@k8s-master Scheduler]# kubectl label node k8s-node3 rack=baz #为节点3把rack标签node/k8s-node3 labeled- 硬亲和与redis运行在雷同节点 都运行在node3上
[root@k8s-master Scheduler]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATESpod-affinity-required-5dd44f5d45-6vvhd 1/1 Running 0 21m 192.168.51.28 k8s-node3 <none> <none>pod-affinity-required-5dd44f5d45-c4hzl 1/1 Running 0 21m 192.168.51.26 k8s-node3 <none> <none>pod-affinity-required-5dd44f5d45-qm6zb 1/1 Running 0 21m 192.168.51.24 k8s-node3 <none> <none>pod-affinity-required-5dd44f5d45-t4mm5 1/1 Running 0 21m 192.168.51.25 k8s-node3 <none> <none>pod-affinity-required-5dd44f5d45-vs7dg 1/1 Running 0 21m 192.168.51.27 k8s-node3 <none> <none>redis-55f46d9795-r7pkz 1/1 Running 0 25m 192.168.51.23 k8s-node3 <none> <none>示例2: podAffinity Pod软亲和
preferredDuringSchedulingIgnoredDuringExecution
[root@k8s-master Scheduler]# cat pod-affinity-preferred-demo.yaml apiVersion: apps/v1kind: Deploymentmetadata: name: redis-preferredspec: replicas: 1 selector: matchLabels: app: redis ctlr: redis-preferred template: metadata: labels: app: redis ctlr: redis-preferred spec: containers: - name: redis image: redis:6.0-alpine resources: requests: cpu: 200m memory: 512Mi---apiVersion: apps/v1kind: Deploymentmetadata: name: pod-affinity-preferredspec: replicas: 4 selector: matchLabels: app: demoapp ctlr: pod-affinity-preferred template: metadata: labels: app: demoapp ctlr: pod-affinity-preferred spec: containers: - name: demoapp image: ikubernetes/demoapp:v1.0 resources: requests: cpu: 500m memory: 100Mi affinity: podAffinity: preferredDuringSchedulingIgnoredDuringExecution: #软亲和以不同权重计算分值重出最终的亲和节点 - weight: 100 podAffinityTerm: labelSelector: matchExpressions: - {key: app, operator: In, values: ["redis"]} - {key: ctlr, operator: In, values: ["redis-prefered"]} #Pod蕴含标签为app=redis、ctlr=redis-prefered同时满足 topologyKey: kubernetes.io/hostname #节点地位标签 以不同节点为地位 示意在雷同节点权重为100 所有同一节点权重最高 - weight: 50 podAffinityTerm: labelSelector: matchExpressions: - {key: app, operator: In, values: ["redis"]} - {key: ctlr, operator: In, values: ["redis-prefered"]} topologyKey: rack #节点标签 地位标签 以机架为地位 示意在雷同机架权重为50[root@k8s-master Scheduler]# kubectl apply -f pod-affinity-preferred-demo.yaml [root@k8s-master Scheduler]# kubectl get pod -o wide #运行在不同的节点NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATESpod-affinity-preferred-57d457968f-4lxvq 1/1 Running 0 5m6s 192.168.113.21 k8s-node1 <none> <none>pod-affinity-preferred-57d457968f-krb2f 1/1 Running 0 5m6s 192.168.113.20 k8s-node1 <none> <none>pod-affinity-preferred-57d457968f-mzckm 1/1 Running 0 5m6s 192.168.12.24 k8s-node2 <none> <none>pod-affinity-preferred-57d457968f-v8n8g 1/1 Running 0 5m6s 192.168.51.37 k8s-node3 <none> <none>redis-preferred-5d775df679-wtpgs 1/1 Running 0 5m6s 192.168.51.38 k8s-node3 <none> <none>示例3: podAntiAffinity 硬反亲和
requiredDuringSchedulingIgnoredDuringExecution
- Deployment 4个正本必须运行在不同的节点上 因为node节点只有3个所有会有个挂起 外部相斥
[root@k8s-master Scheduler]# cat pod-antiaffinity-required-demo.yaml apiVersion: apps/v1kind: Deploymentmetadata: name: pod-antiaffinity-requiredspec: replicas: 4 #运行4个正本 selector: matchLabels: app: demoapp ctlr: pod-antiaffinity-required template: metadata: labels: app: demoapp ctlr: pod-antiaffinity-required spec: containers: - name: demoapp image: ikubernetes/demoapp:v1.0 affinity: podAntiAffinity: requiredDuringSchedulingIgnoredDuringExecution: - labelSelector: matchExpressions: - {key: app, operator: In, values: ["demoapp"]} - key: ctlr operator: In values: ["pod-antiaffinity-required"] #Pod蕴含标签app=demoapp、ctlr=pod-antiaffinity-required 同时满足 topologyKey: kubernetes.io/hostname #以节点为地位 示意每个节点只能运行1个Pod[root@k8s-master Scheduler]# kubectl apply -f pod-antiaffinity-required-demo.yaml [root@k8s-master Scheduler]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATESpod-antiaffinity-required-697f7d764d-hgkxj 1/1 Running 0 5m5s 192.168.113.34 k8s-node1 <none> <none>pod-antiaffinity-required-697f7d764d-n4zt9 1/1 Running 0 5m5s 192.168.12.34 k8s-node2 <none> <none>pod-antiaffinity-required-697f7d764d-psqfb 1/1 Running 0 5m5s 192.168.51.53 k8s-node3 <none> <none>pod-antiaffinity-required-697f7d764d-q6t7m 0/1 Pending 0 5m5s <none> <none> <none> <none> #挂起 因为只有3个node节点