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.affinity
KIND: Pod
VERSION: v1
RESOURCE: 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.podAntiAffinity
FIELDS:
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/v1
kind: Deployment
metadata:
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/v1
kind: Deployment
metadata:
name: pod-affinity-required
spec:
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 unchanged
deployment.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 GATES
pod-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 GATES
pod-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/v1
kind: Deployment
metadata:
name: redis-preferred
spec:
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/v1
kind: Deployment
metadata:
name: pod-affinity-preferred
spec:
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 GATES
pod-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/v1
kind: Deployment
metadata:
name: pod-antiaffinity-required
spec:
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 GATES
pod-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