k8s问题集锦

minikube start直接启动后，Create a Deployment时下载镜像失败

报错：Failed to pull image “k8s.gcr.io/echoserver:1.4”: rpc error: code = Unknown desc = Error response from daemon: Get “https://k8s.gcr.io/v2/”: dial tcp 108.177.125.82:443: i/o timeout (Client.Timeout exceeded while awaiting headers
分析：由于网络和防火墙的原因，通常会无法拉取k8s相关镜像或者下载速度过于缓慢，因此，我们可以通过参数–image-repository来设置Minikube使用阿里云镜像
解决：minikube start --image-repository=registry.cn-hangzhou.aliyuncs.com/google_containers

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minikube service返回的url请求拒绝连接

背景：
kubectl create deployment nginx --image=nginx:1.14.2
kubectl expose deployment nginx --port=80 --type=NodePort
minikube service nginx
分析：由于minikube start启动时，自动选择了docker作为驱动，minikube运行在docker容器内，不是直接运行在主机上的
minikube ip为docker容器的ip, minikube ssh登录到容器后，minikube-id:node-port可以正常访问
minikube start --driver=docker 配置驱动(新版k8s无法配置)
解决：kubectl port-forward service/nginx 8080:80--通过localhost:8080成功访问

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volumes-volumeMounts，pod-pv-pvc之间的调用关系

PersistenVolume（PV）：Kubernetes中的一个存储资源对象
PersistentVolumeClaim（PVC）：让用户不需要关心具体的Volume实现细节

参考：https://www.cnblogs.com/fat-girl-spring/p/14545547.html

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minikube部署mysql,指定启动命令“mysqld --lower_case_table_names=1 --skip-ssl --character_set_server=utf8 --explicit_defaults_for_timestamp”

示例：
下面展示一些 内联代码片。

apiVersion: apps/v1
kind: Deployment
metadata:
  name: ivas-mysql
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: ivas-mysql
  template:
    metadata:
      labels:
        app: ivas-mysql
    spec:
      volumes:
      - name: data
        emptyDir: {}
      containers:
      - name: mysql
        image: mysql:5.7.20
        env:
        - name: MYSQL_USER
          value: ivas
        - name: MYSQL_PASSWORD
          value: QWE123rt 
        - name: MYSQL_ROOT_PASSWORD
          value: QWE123rt
        - name: MYSQL_DATABASE
          value: ivas
        command:
        - mysqld
        - --user=mysql
        - --lower_case_table_names=1
        - --skip-ssl
        - --character_set_server=utf8
        - --explicit_defaults_for_timestamp
        ports:
        - containerPort: 3306
        volumeMounts:
        - name: data
          mountPath: /var/lib/mysql/
      initContainers :
      - name: mysql-init
        image: mysql:5.7.20
        env:
        - name: MYSQL_USER
          value: ivas
        - name: MYSQL_PASSWORD
          value: QWE123rt 
        - name: MYSQL_ROOT_PASSWORD
          value: QWE123rt
        - name: MYSQL_DATABASE
          value: ivas
        command:
        - mysqld
        - --initialize-insecure
        - --user=mysql
        ports:
        - containerPort: 3306
        volumeMounts:
        - name: data
          mountPath: /var/lib/mysql/
---
apiVersion: v1
kind: Service
metadata:
  name: ivas-mysql
  namespace: default
spec:
  selector:
    app: ivas-mysql
  type: NodePort
  ports:
  - port: 3306

注：使用了initContainers，env配置参数无效了
异常：Please read “Security” section of the manual to find out how to run mysqld as root!
处理：启动命令增加参数 --user=mysql
异常：Can’t open and lock privilege tables: Table ‘mysql.user’ doesn’t exist
处理：通过initContainers运行命令“mysqld --initialize-insecure --user=mysql“，初始化mysql
注：–initialize-insecure初始化时，root无登录密码，可以通过以下命令修改密码
use mysql；
update user set authentication_string=password(“QWE123rt”) where user=“root”；
异常：执行kubectl port-forward service/ivas-mysql 3306:3306命令，暴露mysql服务，客户端连接时异常”mysql is not allowed to connect to this mysql server“
处理：update user set host = ‘%’ where user =‘root’;

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Deployment与ReplicaSet关系

1、通过kubectl create 创建一个deployment，那么此时就会调用Deployment-Controller（deployment控制器）创建一个ReplicaSet
2、ReplicaSet调用ReplicaSet-Controller创建pod
3、Pod创建完之后就会由启用资源调度程序，pod分配对应的node节点，由kubelet管理pod

Deployment与StatefulSet区别