技术学堂
为了使kubernetes更高效更稳定，往往需要针对操作系统层或Kubernetes本身在内存调度策略、磁盘使用策略、网络策略等方面进行优化，本节内容将讲述如何针对节点亲和性和Pod亲和性进行优化。
亲和性调度可以分成软策略和硬策略两种方式：
- 软策略是指在没有满足调度要求的节点的时候，pod将忽略这条规则，继续完成调度过程，即：能满足条件最好，不满足也无所谓
- 硬策略是指必须存在满足条件的节点，否则pod将无法部署(为pendding状态)，直到发现满足条件的节点，即：必须满足指定要求
软硬策略实例：
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 |
apiVersion: apps/v1beta1 kind: Deployment metadata: name: affinity labels: app: affinity spec: replicas: 5 revisionHistoryLimit: 15 template: metadata: labels: app: affinity role: test spec: containers: - name: nginx image: nginx:1.16.1 ports: - containerPort: 80 name: webproxy affinity: nodeAffinity: # 硬策略 requiredDuringSchedulingIgnoredDuringExecution: nodeSelectorTerms: - matchExpressions: - key: kubernetes.io/hostname operator: NotIn values: - node03 # 软策略 preferredDuringSchedulingIgnoredDuringExecution: - weight: 1 preference: matchExpressions: - key: com operator: In values: - highmemorynodes |
节点亲和性(nodeAffinity)
节点亲和性是用于控制pod部署在指定的node的机制，以label值为匹配逻辑，Kubernetes提供：
| 操作符 | 说明 |
| In | label值在指定列表中 |
| NotIn | label值不在指定列表中 |
| Gt | label值大于指定值 |
| Lt | label值小于指定值 |
| Exists | label存在 |
| DoesNotExist | label不存在 |
此外，还可以将指定的node标记为“污点(taints)”，除非pod也被标识为可以容忍污节点，否则该Taints节点上将不会部署pod，标记污节点的命令：
|
1 |
kubectl taint nodes node01 test=node01:NoSchedule |
此时，如果需要将某pod部署到node1，则需配置为：
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 |
apiVersion: apps/v1beta1 kind: Deployment metadata: name: taint labels: app: taint spec: replicas: 5 revisionHistoryLimit: 15 template: metadata: labels: app: taint spec: containers: - name: nginx image: nginx:1.16.1 ports: - name: http containerPort: 80 tolerations: - key: "node-role.kubernetes.io/master" operator: "Exists" effect: "NoSchedule" |
Pod亲和性(podAffinity)
Pod亲和性用于控制pod可以和指定的pod可以部署在同一个拓扑域中，另外一个概念是pod反亲和性，则是表示控制pod不能和指定的pod部署在同一个拓扑域中。
举个pod亲和例子：
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 |
apiVersion: apps/v1beta1 kind: Deployment metadata: name: affinity labels: app: affinity spec: replicas: 5 revisionHistoryLimit: 15 template: metadata: labels: app: affinity role: test spec: containers: - name: nginx image: nginx:1.16.1 ports: - containerPort: 80 name: webproxy affinity: podAffinity: requiredDuringSchedulingIgnoredDuringExecution: - labelSelector: matchExpressions: - key: app operator: In values: - highperformancenodes topologyKey: kubernetes.io/hostname |
举个pop反亲和例子：
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 |
apiVersion: apps/v1beta1 kind: Deployment metadata: name: affinity labels: app: affinity spec: replicas: 5 revisionHistoryLimit: 15 template: metadata: labels: app: affinity role: test spec: containers: - name: nginx image: nginx:1.61.1 ports: - containerPort: 80 name: webproxy affinity: podAntiAffinity: requiredDuringSchedulingIgnoredDuringExecution: - labelSelector: matchExpressions: - key: app operator: In values: - lowmemorynodes topologyKey: kubernetes.io/hostname |
原创文章禁止转载：技术学堂 » Kubernetes常见优化之Node/Pod亲和
