kubernetes（三）

1. k8s弹性伸缩

k8s弹性伸缩，需要附加插件heapster

1.1 安装heapster监控

使用heapster(低版本)可以监控pod压力大不大
使用hpa调节pod数量，自动扩容或者缩容

1.先去连接api-server，然后拿到node节点的信息
2. 再去node节点监控取值，把值存储到数据库
3. 然后用grafana出图，可以用dashboard调用

开始安装heapster监控：

批量导入镜像:
[root@k8s-node-2 heapster]# for image in `ls *.tar.gz`; do docker load -i $image; done
[root@k8s-node-2 heapster]# docker tag docker.io/kubernetes/heapster_grafana:v2.6.0 10.0.0.11:5000/heapster_grafana:v2.6.0 
[root@k8s-node-2 heapster]# docker tag docker.io/kubernetes/heapster_influxdb:v0.5 10.0.0.11:5000/heapster_influxdb:v0.5
[root@k8s-node-2 heapster]# docker tag docker.io/kubernetes/heapster:canary 10.0.0.11:5000/heapster:canary


编写资源清单:
(1)"grafana-service.yaml"资源清单
[root@k8s-master heapster]# cat grafana-service.yaml 
apiVersion: v1
kind: Service
metadata:
  labels:
    kubernetes.io/cluster-service: 'true'
    kubernetes.io/name: monitoring-grafana
  name: monitoring-grafana
  namespace: kube-system
spec:
  ports:
  - port: 80
    targetPort: 3000
  selector:
    name: influxGrafana


(2)"heapster-controller.yaml"资源清单
[root@k8s-master heapster]# cat heapster-controller.yaml 
apiVersion: v1
kind: ReplicationController
metadata:
  labels:
    k8s-app: heapster
    name: heapster
    version: v6
  name: heapster
  namespace: kube-system
spec:
  replicas: 1
  selector:
    k8s-app: heapster
    version: v6
  template:
    metadata:
      labels:
        k8s-app: heapster
        version: v6
    spec:
      nodeName: 10.0.0.13
      containers:
      - name: heapster
        image: 10.0.0.11:5000/heapster:canary
        imagePullPolicy: IfNotPresent
        command:
        - /heapster
        - --source=kubernetes:http://10.0.0.11:8080?inClusterConfig=false
        # monitoring-influxdb依赖dns配置，必须要安装k8s的dns
        - --sink=influxdb:http://monitoring-influxdb:8086


(3)"heapster-service.yaml"资源清单
[root@k8s-master heapster]# cat heapster-service.yaml 
apiVersion: v1
kind: Service
metadata:
  labels:
    kubernetes.io/cluster-service: 'true'
    kubernetes.io/name: Heapster
  name: heapster
  namespace: kube-system
spec:
  ports:
  - port: 80
    targetPort: 8082
  selector:
    k8s-app: heapster


(4)"influxdb-grafana-controller.yaml"清单
[root@k8s-master heapster]# cat influxdb-grafana-controller.yaml 
apiVersion: v1
kind: ReplicationController
metadata:
  labels:
    name: influxGrafana
  name: influxdb-grafana
  namespace: kube-system
spec:
  replicas: 1
  selector:
    name: influxGrafana
  template:
    metadata:
      labels:
        name: influxGrafana
    spec:
      nodeName: 10.0.0.13
      containers:
      - name: influxdb
        image: 10.0.0.11:5000/heapster_influxdb:v0.5
        volumeMounts:
        - mountPath: /data
          name: influxdb-storage
      - name: grafana
        image: 10.0.0.11:5000/heapster_grafana:v2.6.0
        env:
          - name: INFLUXDB_SERVICE_URL
            value: http://monitoring-influxdb:8086
          - name: GF_AUTH_BASIC_ENABLED
            value: "false"
          - name: GF_AUTH_ANONYMOUS_ENABLED
            value: "true"
          - name: GF_AUTH_ANONYMOUS_ORG_ROLE
            value: Admin
          - name: GF_SERVER_ROOT_URL
            value: /api/v1/proxy/namespaces/kube-system/services/monitoring-grafana/
        volumeMounts:
        - mountPath: /var
          name: grafana-storage
      volumes:
      - name: influxdb-storage
        emptyDir: {}
      - name: grafana-storage
        emptyDir: {}

(5)"influxdb-service.yaml"资源清单
[root@k8s-master heapster]# cat influxdb-service.yaml 
apiVersion: v1
kind: Service
metadata:
  labels: null
  name: monitoring-influxdb
  namespace: kube-system
spec:
  ports:
  - name: http
    port: 8083
    targetPort: 8083
  - name: api
    port: 8086
    targetPort: 8086
  selector:
    name: influxGrafana

# 进行验证
[root@k8s-master heapster]# kubectl apply -f .
[root@k8s-master heapster]# kubectl get all -n kube-system
## 多了heapter和grafana服务
[root@k8s-master heapster]# kubectl cluster-info

1.2 弹性伸缩使用和验证

(1) 编写一个deployment资源和svc资源实现访问

[root@k8s-master deployment]# cat 01-deploy.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 2
  template:
    metadata:
      labels:
        app: dk-nginx
    spec:
      containers:
      - name: nginx
        image: 10.0.0.11:5000/nginx:1.13
        ports:
        - containerPort: 80
        resources:
          limits:
            cpu: 100m
            memory: 50M
          requests:
            cpu: 100m
            memory: 50M

[root@k8s-master svc]# cat k8s_svc.yaml
apiVersion: v1
kind: Service  # 简称svc
metadata:
  name: myweb
spec:
  type: NodePort  # 默认类型为ClusterIP
  ports:
    - port: 80  # clusterVIP端口
      nodePort: 30000  # 指定基于NodePort类型对外暴露的端口，若不指定，则会在"30000-32767"端口访问内随机挑选一个未监听的端口暴露
      targetPort: 80  # 指定后端Pod服务监听的端口
  selector:
    app: ycy-web  # 指定匹配的Pod对应的标签

（2）生成一个hpa资源

# 1. 命令行的形式生成，在内存中有hpa的yaml，--max:指定最大的Pod数量, --min:指定最小的Pod数量,  --cpu-percent:指定CPU的百分比
[root@k8s-master k8s_yaml]#  kubectl autoscale deployment nginx --max=10 --min=1 --cpu-percent=10

# 2. 导出刚刚设置的hpa的yaml
 [root@k8s-master k8s_yaml]# kubectl get hpa nginx -o yaml
apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
  name: nginx
  namespace: default
spec:
  maxReplicas: 10
  minReplicas: 1
  scaleTargetRef:
    apiVersion: extensions/v1beta1
    kind: Deployment
    name: nginx
  targetCPUUtilizationPercentage: 10

# （3） 查看hpa资源
[root@k8s-master k8s_yaml]# kubectl get all
[root@k8s-master k8s_yaml]# kubectl get rs -o wide
[root@k8s-master k8s_yaml]# kubectl get hpa nginx -o yaml
[root@k8s-master k8s_yaml]# kubectl describe hpa nginx
[root@k8s-master k8s_yaml]# kubectl describe deployment nginx

（3） 进行压测，验证是否自动伸缩

# 1. 安装ab压测工具
[root@k8s-master k8s_yaml]# yum install httpd-tools -y
# 2. -n 发起请求数  -c 并发数
[root@k8s-master k8s_yaml]# ab -n 10000 -c 2000  http://10.0.0.12:30148/

常用命令：

kubectl get all -n kube-system
kubectl cluster-info 
# 查看pod的资源使用情况
kubectl top -n default pod test-32rf5
# 删除对应的资源
kubectl delete rc --all
kubectl delete deploment --all
kubectl delete daemonset --all

2. 持久化存储

tomcat+mysql的案例中，Pod成功后可以添加自定义的数据，数据被存储在MySQL数据库实例中，批量删除容器，docker rm -f `docker ps -a -q，删除容器后，这些容器会被K8S重新创建，尽管业务恢复了，但我们的数据也丢失了。为了解决容器被删除后数据不丢失，则引入了存储类型，类似于docker中的数据卷

提示：以通过kubectl exec -it mysql-698607359-dvmzk bash进入到容器并通过"env"查看MySQL的root用户密码

数据卷的分类：

数据卷:
	(1)kubernetes中的Volume提供了在容器中挂载外部存储的能力;
	(2)Pod需要设置卷来源(po.spec.volumes)和挂载点(po.spec.containers.volumeMounts)两个信息后才可以使用相应的volume;
	
数据卷类型大致分类:
	本地数据卷:
		hostPath，emptyDir等。
	网络数据卷:
		NFS，Ceph，GlusterFS等。
	公有云:
		AWS,EBS等;
	K8S资源:
		configmap，secret等。
官方文档: https://kubernetes.io/docs/concepts/storage/volumes/

2.1 emptyDir

查看帮助文档 kubectl explain pod.spec.containers.volumeMounts

emptyDir 临时的空目录，随着pod的生命周期，删掉pod，空目录内的内容也会小时，想实现数据共享就不能使用emptyDir资源，deploment 设置了三个pod，那么每个pod都会生成一个empty，所以多个Pod不能使用该类型进行数据共享，但同一个Pod的多个容器可以基于该类型进行数据共享。

使用场景：存放日志，pod与pod之间empty挂载不同的数据

spec:
  nodeName: 10.0.0.13
  volumes:
  - name: mysql-data
    emptyDir: {}
  containers:
    - name: wp-mysql
      image: 10.0.0.11:5000/mysql:5.7
      imagePullPolicy: IfNotPresent
      ports:
      - containerPort: 3306
      volumeMounts:
      - name: mysql-data
        mountPath: /var/lib/mysql