需求：
Pod和Node之间的关系
某些Pod优先选择有ssd=true标签的节点，如果没有在考虑部署到其它节点；
某些Pod需要部署在ssd=true和type=physical的节点上，但是优先部署在ssd=true的节点上；
Pod和Pod之间的关系
同一个应用的Pod不同的副本或者同一个项目的应用尽量或必须不部署在同一个节点或者符合某个标签的一类节点上或者不同的区域；
相互依赖的两个Pod尽量或必须部署在同一个节点上或者同一个域内。
Affinity分类
image.png
节点亲和力配置详解
apiVersion: v1
kind: Pod
metadata:
name: with-node-affinity
spec:
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution: # 硬亲和力配置
nodeSelectorTerms: # 节点选择器配置，可以配置多个matchExpressions（满足其一），每个matchExpressions下可以配置多个key、value类型的选择器（都需要满足），其中values可以配置多个（满足其一）
- matchExpressions:
- key: kubernetes.io/e2e-az-name
operator: In # 标签匹配的方式
# In：相当于key = value的形式
# NotIn：相当于key != value的形式
# Exists：节点存在label的key为指定的值即可，不能配置values字段
# DoesNotExist：节点不存在label的key为指定的值即可，不能配置values字段
values:
- e2e-az1
- az-2
preferredDuringSchedulingIgnoredDuringExecution: # 软亲和力配置
- weight: 1 # 软亲和力的权重，权重越高优先级越大，范围1-100
preference: # 软亲和力配置项，和weight同级，可以配置多个
matchExpressions: # 和硬亲和力一致
- key: another-node-label-key
operator: In # 标签匹配的方式
# In：相当于key = value的形式
# NotIn：相当于key != value的形式
# Exists：节点存在label的key为指定的值即可，不能配置values字段
# DoesNotExist：节点不存在label的key为指定的值即可，不能配置values字段
values:
- another-node-label-value
containers:
- name: with-node-affinity
image: nginx
Pod亲和力和反亲和力详解
apiVersion: v1
kind: Pod
metadata:
name: with-pod-affinity
spec:
affinity:
podAffinity: # pod亲和力配置
requiredDuringSchedulingIgnoredDuringExecution: # 硬亲和力配置
- labelSelector: # Pod的lableSelector配置，可以配置多个
matchExpressions: # 配置和节点亲和力配置一致
- key: security
operator: In # 配置和节点亲和力一致
values:
- S1
topologyKey: failure-domain.beta.kubernetes.io/zone # 匹配的拓扑域的key，也就是节点上label的key，key和value相同的为同一个域，可以用于标注不同的机房和地区
podAntiAffinity: # pod反亲和力配置
preferredDuringSchedulingIgnoredDuringExecution: # 软亲和力配置
- weight: 100
podAffinityTerm:
labelSelector:
matchExpressions:
- key: security
operator: In
values:
- S2
namespaces: # 和哪个命名空间的Pod进行匹配，空为default命名空间，可以写多个namespace
- default
topologyKey: failure-domain.beta.kubernetes.io/zone # 匹配的拓扑域的key，也就是节点上label的key，key和value相同的为同一个域，可以用于标注不同的机房和地区
containers:
- name: with-pod-affinity
image: nginx
示例1：同一个应用部署在不同的宿主机
使用pod的亲和力app=must-be-diff-nodes， 通过节点默认label topologyKey: kubernetes.io/hostname 实现每个pod都调度到不同的宿主机
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: must-be-diff-nodes
name: must-be-diff-nodes
namespace: kube-public
spec:
replicas: 3
selector: # Pod选择器配置，可以配置多个
matchLabels: # 配置和节点亲和力一致
app: must-be-diff-nodes
template:
metadata:
labels:
app: must-be-diff-nodes
spec:
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: app
operator: In # 配置和节点亲和力一致
values:
- must-be-diff-nodes
topologyKey: kubernetes.io/hostname # 匹配的拓扑域的key，也就是节点上label的key，key和value相同的为同一个域，可以用于标注不同的机房和地区
containers:
- image: nginx
imagePullPolicy: IfNotPresent
name: must-be-diff-nodes
示例2：同一个应用不同副本固定节点
使用pod反亲和力app=store，通过topologyKey: "kubernetes.io/hostname"实现多副本的pod，不调度到同一台节点上
apiVersion: apps/v1
kind: Deployment
metadata:
name: redis-cache
spec:
selector:
matchLabels:
app: store
replicas: 3
template:
metadata:
labels:
app: store
spec:
nodeSelector:
app: store
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: app
operator: In
values:
- store
topologyKey: "kubernetes.io/hostname"
containers:
- name: redis-server
image: redis:3.2-alpine
示例3：应用和缓存尽量部署在同一个域内
使用pod的硬亲和性和软亲和性，实现pod app=store的label尽量部署在同一个域中
apiVersion: apps/v1
kind: Deployment
metadata:
name: web-server
spec:
selector:
matchLabels:
app: web-store
replicas: 3
template:
metadata:
labels:
app: web-store
spec:
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: app
operator: In
values:
- web-store
topologyKey: "kubernetes.io/hostname"
podAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- weight: 100
podAffinityTerm:
labelSelector:
matchExpressions:
- key: app
operator: In
values:
- store
topologyKey: "kubernetes.io/hostname"
containers:
- name: web-app
image: nginx:1.16-alpine
示例4：尽量调度到高配置服务器
通过节点的硬亲和性，一次匹配ssd=true，weight100，weight10
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: prefer-ssd
name: prefer-ssd
namespace: kube-public
spec:
replicas: 3
selector:
matchLabels:
app: prefer-ssd
template:
metadata:
creationTimestamp: null
labels:
app: prefer-ssd
spec:
affinity:
nodeAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- preference:
matchExpressions:
- key: ssd
operator: In
values:
- "true"
- key: master
operator: NotIn
values:
- "true"
weight: 100
- preference:
matchExpressions:
- key: type
operator: In
values:
- physical
weight: 10
containers:
- env:
- name: TZ
value: Asia/Shanghai
- name: LANG
value: C.UTF-8
image: nginx
imagePullPolicy: IfNotPresent
name: prefer-ssd
TopologyKey配置详解
匹配的拓扑域的key，也就是节点上label的key，key和value相同的为同一个域，可以用于标注不同的机房和地区
image.png
image.png
示例：同一个应用多区域部署
通过pod的硬亲和性，和topologyKey node节点的同一个key，不同的value实现多区域部署
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: must-be-diff-zone
name: must-be-diff-zone
namespace: kube-public
spec:
replicas: 3
selector:
matchLabels:
app: must-be-diff-zone
template:
metadata:
labels:
app: must-be-diff-zone
spec:
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: app
operator: In
values:
- must-be-diff-zone
topologyKey: region # region为node的label，上述图中，region分别=daxing、chaoyang
containers:
- image: nginx
imagePullPolicy: IfNotPresent
name: must-be-diff-zone
