zookeeper

Headless Service - zk-headless ConfigMap - zk-config PodDisruptionBudget - zk-budget StatefulSet - zk

watch the StatefulSet controller create

kubectl get pods -w -l app=zk

get hostname

for i in 0 1 2; do kubectl exec zk-$i -- hostname; done

StatefulSet controller 提供每个Pod 一个unique hostname（-）

Examine the contents of the myid file for each server

for i in 0 1 2; do echo "myid zk-$i";kubectl exec zk-$i -- cat /var/lib/zookeeper/data/myid; done

zk-headless 为所有pod创建，FQDN (Fully Qualified Domain Name)

for i in 0 1 2; do kubectl exec zk-$i -- hostname -f; done

zk-0.zk-headless.default.svc.cluster.local
zk-1.zk-headless.default.svc.cluster.local
zk-2.zk-headless.default.svc.cluster.local

zk的配置文件zoo.cfg

kubectl exec zk-0 -- cat /opt/zookeeper/conf/zoo.cfg

clientPort=2181
dataDir=/var/lib/zookeeper/data
dataLogDir=/var/lib/zookeeper/log
tickTime=2000
initLimit=10
syncLimit=2000
maxClientCnxns=60
minSessionTimeout= 4000
maxSessionTimeout= 40000
autopurge.snapRetainCount=3
autopurge.purgeInteval=0
server.1=zk-0.zk-headless.default.svc.cluster.local:2888:3888
server.2=zk-1.zk-headless.default.svc.cluster.local:2888:3888
server.3=zk-2.zk-headless.default.svc.cluster.local:2888:3888

headless顺序创建pod

测试zookeeper， zk-0写world到路径／hello

kubectl exec zk-0 zkCli.sh create /hello world

在zk-1获取／hello

kubectl exec zk-1 zkCli.sh get /hello

删除 stateful zk

kubectl delete statefulset zk
statefulset "zk" deleted

查看Pod删除过程

kubectl get pods -w -l app=zk

重新apply zookeeper.yaml

kubectl apply -f https://k8s.io/docs/tutorials/stateful-application/zookeeper.yaml

kubectl get pods -w -l app=zk

查看／hello上面的数据是否还在

kubectl exec zk-2 zkCli.sh get /hello

因为持久化到硬盘

查看pvc

kubectl get pvc -l app=zk

ConfigMap

apiVersion: v1
kind: ConfigMap
metadata:
  name: zk-config
data:
  ensemble: "zk-0;zk-1;zk-2"
  jvm.heap: "1G"
  tick: "2000"
  init: "10"
  sync: "5"
  client.cnxns: "60"
  snap.retain: "3"
  purge.interval: "1"

查看容器ENV

for i in 0 1 2; do kubectl exec zk-$i env | grep ZK_*;echo""; done

查看zk User Pod template

securityContext:
  runAsUser: 1000
  fsGroup: 1000

查看zk user

kubectl exec zk-0 -- ps -elf

kill zk process

kubectl exec zk-0 -- ps -ef
kubectl get pod -w -l app=zk
kubectl exec zk-0 -- pkill java

Liveness

Pod template

livenessProbe:
        exec:
          command:
          - "zkOk.sh"
        initialDelaySeconds: 15
        timeoutSeconds: 5

验证

kubectl get pod -w -l app=zk kubectl exec zk-0 -- rm /opt/zookeeper/bin/zkOk.sh kubectl get pod -w -l app=zk

部署到不同node affinity：requiredDuringSchedulingRequiredDuringExecution告诉schedule不要co-locate两个pod到同一个node

affinity:
  podAntiAffinity:
    requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
            - key: "app"
              operator: In
              values: 
              - zk-headless
        topologyKey: "kubernetes.io/hostname"

验证：

for i in 0 1 2; do kubectl get pod zk-$i --template {{.spec.nodeName}}; echo ""; done

poddisruptionbudget

定义最少zk pod必须存活

kubectl get poddisruptionbudget zk-budget

NAME        MIN-AVAILABLE   ALLOWED-DISRUPTIONS   AGE
zk-budget   2               1                     1h