K8S 高級調度方式

時間  2019-12-20
標籤 k8s 高級 調度 方式 简体版
原文   原文鏈接

能夠使用高級調度分爲：node

  • 節點選擇器： nodeSelector、nodeName
  • 節點親和性調度： nodeAffinity
  • Pod親和性調度：PodAffinity
  • Pod反親和性調度：podAntiAffinity

nodeSelector, nodeName

cd; mkdir schedule; cd schedule/

vi pod-demo.yaml
# 內容爲
apiVersion: v1
kind: Pod
metadata:
  name: pod-demo
  labels:
    app: myapp
    tier: frontend
spec:
  containers:
  - name: myapp
    image: ikubernetes/myapp:v1
  nodeSelector:
    disktype: harddisk


kubectl apply -f pod-demo.yaml 
kubectl get pods

kubectl describe pod  pod-demo
# 運行結果:
Warning  FailedScheduling  2m3s (x25 over 3m15s)  default-scheduler  0/3 nodes are available: 3 node(s) didn't match node selector.

# 打上標籤
kubectl label node node2 disktype=harddisk

# 正常啓動
kubectl get pods

nodeAffinity

requiredDuringSchedulingIgnoredDuringExecution 硬親和性 必須知足親和性。
preferredDuringSchedulingIgnoredDuringExecution 軟親和性 能知足最好，不知足也不要緊。數據庫

硬親和性：
matchExpressions : 匹配表達式,這個標籤能夠指定一段，例如pod中定義的key爲zone，operator爲In(包含那些)，values爲 foo和bar。就是在node節點中包含foo和bar的標籤中調度
matchFields : 匹配字段 和上面的意思 不過他能夠不定義標籤值，能夠定義api

# 選擇在 node 有 zone 標籤值爲 foo 或 bar 值的節點上運行 pod
vi pod-nodeaffinity-demo.yaml 
# 內容爲
apiVersion: v1
kind: Pod
metadata:
  name: pod-node-affinity-demo
  labels:
    app: myapp
    tier: frontend
spec:
  containers:
  - name: myapp
    image: ikubernetes/myapp:v1
  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
        nodeSelectorTerms:
        - matchExpressions:
          - key: zone
            operator: In
            values:
            - foo
            - bar

kubectl apply -f pod-nodeaffinity-demo.yaml

kubectl describe pod pod-node-affinity-demo
# 運行結果:
Warning  FailedScheduling  2s (x8 over 20s)  default-scheduler  0/3 nodes are available: 3 node(s) didn't match node selector.

# 給其中一個node打上foo的標籤
kubectl label node node1 zone=foo

# 正常啓動
kubectl get pods

軟親和性 :app

cp pod-nodeaffinity-demo.yaml pod-nodeaffinity-demo-2.yaml 

vi pod-nodeaffinity-demo-2.yaml 
# 內容爲
apiVersion: v1
kind: Pod
metadata:
  name: pod-node-affinity-demo-2
  labels:
    app: myapp
    tier: frontend
spec:
  containers:
  - name: myapp
    image: ikubernetes/myapp:v1
  affinity:
    nodeAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
      - preference:
          matchExpressions:
          - key: zone
            operator: In
            values:
            - foo
            - bar
        weight: 60

kubectl apply -f pod-nodeaffinity-demo-2.yaml

podAffinity

Pod親和性場景，咱們的k8s集羣的節點分佈在不一樣的區域或者不一樣的機房，當服務A和服務B要求部署在同一個區域或者同一機房的時候，咱們就須要親和性調度了。frontend

labelSelector : 選擇跟那組Pod親和
namespaces : 選擇哪一個命名空間
topologyKey : 指定節點上的哪一個鍵ide

kubectl get pods
kubectl delete pod pod-node-affinity-demo pod-node-affinity-demo-2 pod-demo

cd ~/schedule/

vi pod-required-affinity-demo.yaml 
# 內容爲：
apiVersion: v1
kind: Pod
metadata:
  name: pod-first
  labels:
    app: myapp
    tier: frontend
spec:
  containers:
  - name: myapp
    image: ikubernetes/myapp:v1
---
apiVersion: v1
kind: Pod
metadata:
  name: pod-second
  labels:
    app: db
    tier: db
spec:
  containers:
  - name: busybox
    image: busybox
    imagePullPolicy: IfNotPresent
    command: ["sh","-c","sleep 3600"]
  affinity:
    podAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - {key: app, operator: In, values: ["myapp"]}
        topologyKey: kubernetes.io/hostname


kubectl apply -f pod-required-affinity-demo.yaml 

kubectl get pods -o wide
# 運行結果，兩個 pod 在同一 node 節點上
NAME         READY   STATUS    RESTARTS   AGE   IP           NODE
pod-first    1/1     Running   0          11s   10.244.1.6   node1
pod-second   1/1     Running   0          11s   10.244.1.5   node1

podAntiAffinity

Pod反親和性場景，當應用服務A和數據庫服務B要求儘可能不要在同一臺節點上的時候。ui

kubectl delete -f pod-required-affinity-demo.yaml 

cp pod-required-affinity-demo.yaml pod-required-anti-affinity-demo.yaml 

vi pod-required-anti-affinity-demo.yaml 
# 內容爲
apiVersion: v1
kind: Pod
metadata:
  name: pod-first
  labels:
    app: myapp
    tier: frontend
spec:
  containers:
  - name: myapp
    image: ikubernetes/myapp:v1
---
apiVersion: v1
kind: Pod
metadata:
  name: pod-second
  labels:
    app: backend
    tier: db
spec:
  containers:
  - name: busybox
    image: busybox:latest
    imagePullPolicy: IfNotPresent
    command: ["sh","-c","sleep 3600"]
  affinity:
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - {key: app, operator: In, values: ["myapp"]}
        topologyKey: kubernetes.io/hostname

kubectl apply -f pod-required-anti-affinity-demo.yaml 

kubectl get pods -o wide
# 運行結果，兩個 pod 不在同一個 node
NAME         READY   STATUS    RESTARTS   AGE   IP           NODE
pod-first    1/1     Running   0          5s    10.244.2.4   node2
pod-second   1/1     Running   0          5s    10.244.1.7   node1

kubectl delete -f pod-required-anti-affinity-demo.yaml 


# 若是硬反親和性定義的標籤兩個節點都有，則第二個 Pod 無法進行調度，以下面的的 zone=foo
# 給兩個 node 打上同一個標籤 zone=foo
kubectl label nodes node2 zone=foo
kubectl label nodes node1 zone=foo

vi pod-required-anti-affinity-demo.yaml 
# 內容爲：
apiVersion: v1
kind: Pod
metadata:
  name: pod-first
  labels:
    app: myapp
    tier: frontend
spec:
  containers:
  - name: myapp
    image: ikubernetes/myapp:v1
---
apiVersion: v1
kind: Pod
metadata:
  name: pod-second
  labels:
    app: backend
    tier: db
spec:
  containers:
  - name: busybox
    image: busybox:latest
    imagePullPolicy: IfNotPresent
    command: ["sh","-c","sleep 3600"]
  affinity:
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - {key: app, operator: In, values: ["myapp"]}
        topologyKey: zone


kubectl apply -f pod-required-anti-affinity-demo.yaml 

kubectl get pods -o wide
# 結果以下，pod-second 無法啓動
NAME         READY   STATUS    RESTARTS   AGE   IP           NODE
pod-first    1/1     Running   0          12s   10.244.1.8   node1
pod-second   0/1     Pending   0          12s   <none>       <none>

kubectl delete -f pod-required-anti-affinity-demo.yaml

污點容忍調度（Taint和Toleration）

taints and tolerations 容許將某個節點作標記，以使得全部的pod都不會被調度到該節點上。可是若是某個pod明確制定了 tolerates 則能夠正常調度到被標記的節點上。spa

# 能夠使用命令行爲 Node 節點添加 Taints：
kubectl taint nodes node1 key=value:NoSchedule

operator能夠定義爲：
Equal：表示key是否等於value，默認
Exists：表示key是否存在，此時無需定義value命令行

tain 的 effect 定義對 Pod 排斥效果:
NoSchedule：僅影響調度過程，對現存的Pod對象不產生影響；
NoExecute：既影響調度過程，也影響顯著的Pod對象；不容忍的Pod對象將被驅逐
PreferNoSchedule: 表示儘可能不調度code

# 查看節點的 taint
kubectl describe node master
kubectl get pods -n kube-system
kubectl describe pods kube-apiserver-master -n kube-system

# 爲 node1 打上污點
kubectl taint node node1 node-type=production:NoSchedule

vi deploy-demo.yaml 
# 內容爲：
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myapp
      release: canary
  template:
    metadata:
      labels:
        app: myapp
        release: canary
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v1
        ports:
        - name: http
          containerPort: 80



kubectl apply -f deploy-demo.yaml 

kubectl get pods -o wide
# 運行結果：
NAME                            READY   STATUS    RESTARTS   AGE   IP           NODE
myapp-deploy-69b47bc96d-cwt79   1/1     Running   0          5s    10.244.2.6   node2
myapp-deploy-69b47bc96d-qqrwq   1/1     Running   0          5s    10.244.2.5   node2


# 爲 node2 打上污點
kubectl taint node node2 node-type=dev:NoExecute

# NoExecute 將會驅逐沒有容忍該污點的 pod，因兩個node節點都有污點，pod沒有定義容忍，致使沒有節點能夠啓動pod
kubectl get pods -o wide
# 運行結果：
NAME                            READY   STATUS    RESTARTS   AGE   IP       NODE
myapp-deploy-69b47bc96d-psl8f   0/1     Pending   0          14s   <none>   <none>
myapp-deploy-69b47bc96d-q296k   0/1     Pending   0          14s   <none>   <none>


# 定義Toleration(容忍)
vi deploy-demo.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myapp
      release: canary
  template:
    metadata:
      labels:
        app: myapp
        release: canary
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v2
        ports:
        - name: http
          containerPort: 80
      tolerations:
      - key: "node-type"
        operator: "Equal"
        value: "production"
        effect: "NoSchedule"


kubectl apply -f deploy-demo.yaml

# pod 容忍 node1 的 tain ，能夠在 node1 上運行
ubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP            NODE
myapp-deploy-65cc47f858-tmpnz   1/1     Running   0          10s   10.244.1.10   node1
myapp-deploy-65cc47f858-xnklh   1/1     Running   0          13s   10.244.1.9    node1


# 定義Toleration，是否存在 node-type 這個key 且 effect 值爲 NoSchedule 
vi deploy-demo.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myapp
      release: canary
  template:
    metadata:
      labels:
        app: myapp
        release: canary
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v2
        ports:
        - name: http
          containerPort: 80
      tolerations:
      - key: "node-type"
        operator: "Exists"
        value: ""
        effect: "NoSchedule"

kubectl apply -f deploy-demo.yaml

kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP            NODE
myapp-deploy-559f559bcc-6jfqq   1/1     Running   0          10s   10.244.1.11   node1
myapp-deploy-559f559bcc-rlwp2   1/1     Running   0          9s    10.244.1.12   node1


##定義Toleration，是否存在 node-type 這個key 且 effect 值爲空，則包含全部的值 
vi deploy-demo.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: myapp
      release: canary
  template:
    metadata:
      labels:
        app: myapp
        release: canary
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v2
        ports:
        - name: http
          containerPort: 80
      tolerations:
      - key: "node-type"
        operator: "Exists"
        value: ""
        effect: ""

kubectl apply -f deploy-demo.yaml

# 兩個 pod 均衡調度到兩個節點
kubectl get pods -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP            NODE
myapp-deploy-5d9c6985f5-hn4k2   1/1     Running   0          2m    10.244.1.13   node1
myapp-deploy-5d9c6985f5-lkf9q   1/1     Running   0          2m    10.244.2.7    node2
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