StatefulSet介绍

暂时略...

实战案例

1. 准备启动redis-server 运行脚本

$ cat launch.sh 
#!/bin/bash

PASSWORD=$(cat /etc/redis-passwd/passwd)

#StatefulSet会给每个POD分配一个固定的主机网络标识符号，所以这里可以通过主机名去判断主节点
if [ "${HOSTNAME}" == "redis-0" ]
then
  redis-server --requirepass ${PASSWORD}
else
  redis-server --slaveof redis-0.redis 6379 --masterauth ${PASSWORD} --requirepass ${PASSWORD}
fi

2. 创建ConfigMap和密码配置Secret

#secret对象存放密码
$ kubectl create secret generic redis-passwd --from-literal=passwd="password"
#configmap对象存放运行脚本
$ kubectl delete configmap redis-config
$ kubectl create configmap redis-config --from-file=launch.sh=launch.sh 
$ kubectl get configmap 
$ kubectl get configmap redis-config -o yaml 

3. 创建Headless Service

$ cat headless-service.yaml
apiVersion: v1
kind: Service
metadata:
  name: "redis"
  labels:
    app: redis
spec:
  ports:
  - port: 6379
    name: redis
  clusterIP: None 
  selector:
    app: redis

4. 创建Statefulset

$ cat statefulset.yaml
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: redis
  namespace: default
spec:
  serviceName: "redis"
  replicas: 3
  selector:
    matchLabels:
      app: redis
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
      - name: redis
        image: redis:5-alpine
        ports:
        - containerPort: 6379
          name: redis
        volumeMounts:
        - name: data
          mountPath: /data
        - name: script
          mountPath: /script/launch.sh
          subPath: launch.sh
        - name: passwd-volume
          mountPath: /etc/redis-passwd
        command:
        - sh
        - -c
        - sleep 10 && sh /script/launch.sh #这里解释下，我在本地测试环境如果不加sleep，启动redis之后会提示找不到/script/launch.sh，我不知道是不是延迟挂载之类，暂时先管，跑起来再说
      volumes:
      - name: script
        configMap:
          name: redis-config
          defaultMode: 0777
      - name: passwd-volume
        secret:
          secretName: redis-passwd
  volumeClaimTemplates:
  - metadata:
      name: data
    spec:
      accessModes: ["ReadWriteOnce"]
      resources:
        requests:
          storage: 1Gi

5. 检查

#每个POD是否被正确分配网络标识
$ kubectl run -i --tty --image busybox:1.28 dns-test --restart=Never --rmkub
If you don't see a command prompt, try pressing enter.
/ # nslookup redis-0.redis
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      redis-0.redis
Address 1: 10.244.1.112 redis-0.redis.default.svc.cluster.local
/ # 

主从环境是否正常初始化