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如何为Spring和MySql设置kubernetes

[英]How to set up kubernetes for Spring and MySql

 原文  2019-09-11 16:57:47  1   1    mysql/ docker/ kubernetes

问题描述

我按照本教程https://medium.com/better-programming/kubernetes-a-detailed-example-of-deployment-of-a-stateful-application-de3de33c8632

我创建了mysql pod和后端pod，但是当应用程序出现错误com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
pod mysql：正在运行
吊舱后端：CrashLoopBackOff

Docker文件 

FROM openjdk:14-ea-8-jdk-alpine3.10
ADD target/credit-0.0.1-SNAPSHOT.jar .
EXPOSE 8200
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom", "-Dspring.profiles.active=container","-jar","/credit-0.0.1-SNAPSHOT.jar"]

信贷部署 

# Define 'Service' to expose backend application deployment
apiVersion: v1
kind: Service
metadata:
  name: to-do-app-backend  
spec:
  selector:  # backend application pod lables should match these
    app: to-do-app
    tier: backend
  ports:
  - protocol: "TCP"
    port: 80
    targetPort: 8080
  type: LoadBalancer   # use NodePort, if you are not running Kubernetes on cloud
---
# Configure 'Deployment' of backend application
apiVersion: apps/v1
kind: Deployment
metadata:
  name: to-do-app-backend
  labels: 
    app: to-do-app
    tier: backend
spec:
  replicas: 2    # Number of replicas of back-end application to be deployed
  selector:
    matchLabels: # backend application pod labels should match these
      app: to-do-app
      tier: backend
  template:
    metadata:
      labels: # Must macth 'Service' and 'Deployment' labels
        app: to-do-app
        tier: backend  
    spec:                 
      containers: 
      - name: to-do-app-backend 
        image: gitim21/credit_repo:1.0  # docker image of backend application
        env:   # Setting Enviornmental Variables
          - name: DB_HOST   # Setting Database host address from configMap
            valueFrom: 
              configMapKeyRef:
                name: db-conf  # name of configMap
                key: host
          - name: DB_NAME  # Setting Database name from configMap
            valueFrom:
              configMapKeyRef:
                name: db-conf 
                key: name
          - name: DB_USERNAME  # Setting Database username from Secret
            valueFrom:
              secretKeyRef:
                name: db-credentials # Secret Name
                key: username
          - name: DB_PASSWORD # Setting Database password from Secret
            valueFrom:
              secretKeyRef:
                name: db-credentials
                key: password     
        ports:
        - containerPort: 8080

application.yml 

spring:
  datasource:
    type: com.zaxxer.hikari.HikariDataSource
    hikari:
      idle-timeout: 10000
    platform: mysql
    username: ${DB_USERNAME}
    password: ${DB_PASSWORD}
    url: jdbc:mysql://${DB_HOST}/${DB_NAME}
  jpa:
    hibernate:
      naming:
        physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

我将application.yml文件放在应用程序文件夹“资源”中

编辑 

Name:               mysql-64c7df597c-s4gbt
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               minikube/192.168.8.160
Start Time:         Thu, 12 Sep 2019 17:50:18 +0200
Labels:             app=mysql
                    pod-template-hash=64c7df597c
                    tier=database
Annotations:        <none>
Status:             Running
IP:                 172.17.0.5
Controlled By:      ReplicaSet/mysql-64c7df597c
Containers:
  mysql:
    Container ID:  docker://514d3f5af76f5e7ac11f6bf6e36b44ee4012819dc1cef581829a6b5b2ce7c09e
    Image:         mysql:5.7
    Image ID:      docker-pullable://mysql@sha256:1a121f2e7590f949b9ede7809395f209dd9910e331e8372e6682ba4bebcc020b
    Port:          3306/TCP
    Host Port:     0/TCP
    Args:
      --ignore-db-dir=lost+found
    State:          Running
      Started:      Thu, 12 Sep 2019 17:50:19 +0200
    Ready:          True
    Restart Count:  0
    Environment:
      MYSQL_ROOT_PASSWORD:  <set to the key 'password' in secret 'db-root-credentials'>  Optional: false
      MYSQL_USER:           <set to the key 'username' in secret 'db-credentials'>       Optional: false
      MYSQL_PASSWORD:       <set to the key 'password' in secret 'db-credentials'>       Optional: false
      MYSQL_DATABASE:       <set to the key 'name' of config map 'db-conf'>              Optional: false
    Mounts:
      /var/lib/mysql from mysql-persistent-storage (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-rgsmp (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  mysql-persistent-storage:
    Type:       PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
    ClaimName:  mysql-pv-claim
    ReadOnly:   false
  default-token-rgsmp:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-rgsmp
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  49m   default-scheduler  Successfully assigned default/mysql-64c7df597c-s4gbt to minikube
  Normal  Pulled     49m   kubelet, minikube  Container image "mysql:5.7" already present on machine
  Normal  Created    49m   kubelet, minikube  Created container mysql
  Normal  Started    49m   kubelet, minikube  Started container mysql

Name:               to-do-app-backend-8669b5467-hrr9q
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               minikube/192.168.8.160
Start Time:         Thu, 12 Sep 2019 18:27:45 +0200
Labels:             app=to-do-app
                    pod-template-hash=8669b5467
                    tier=backend
Annotations:        <none>
Status:             Running
IP:                 172.17.0.7
Controlled By:      ReplicaSet/to-do-app-backend-8669b5467
Containers:
  to-do-app-backend:
    Container ID:   docker://1eb8453939710aed7a93cddbd5046f49be3382858aa17d5943195207eaeb3065
    Image:          gitim21/credit_repo:1.0
    Image ID:       docker-pullable://gitim21/credit_repo@sha256:1fb2991394fc59f37068164c72263749d64cb5c9fe741021f476a65589f40876
    Port:           8080/TCP
    Host Port:      0/TCP
    State:          Waiting
      Reason:       CrashLoopBackOff
    Last State:     Terminated
      Reason:       Error
      Exit Code:    1
      Started:      Thu, 12 Sep 2019 18:51:25 +0200
      Finished:     Thu, 12 Sep 2019 18:51:36 +0200
    Ready:          False
    Restart Count:  9
    Environment:
      DB_HOST:      <set to the key 'host' of config map 'db-conf'>         Optional: false
      DB_NAME:      <set to the key 'name' of config map 'db-conf'>         Optional: false
      DB_USERNAME:  <set to the key 'username' in secret 'db-credentials'>  Optional: false
      DB_PASSWORD:  <set to the key 'password' in secret 'db-credentials'>  Optional: false
      DB_PORT:      <set to the key 'port' in secret 'db-credentials'>      Optional: false
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-rgsmp (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             False
  ContainersReady   False
  PodScheduled      True
Volumes:
  default-token-rgsmp:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-rgsmp
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type     Reason     Age                  From               Message
  ----     ------     ----                 ----               -------
  Normal   Scheduled  25m                  default-scheduler  Successfully assigned default/to-do-app-backend-8669b5467-hrr9q to minikube
  Normal   Pulled     23m (x5 over 25m)    kubelet, minikube  Container image "gitim21/credit_repo:1.0" already present on machine
  Normal   Created    23m (x5 over 25m)    kubelet, minikube  Created container to-do-app-backend
  Normal   Started    23m (x5 over 25m)    kubelet, minikube  Started container to-do-app-backend
  Warning  BackOff    50s (x104 over 25m)  kubelet, minikube  Back-off restarting failed container

1 个解决方案

解决方案1
 0  2019-09-12 06:28:57

首先，请确保您满足本文中描述的所有要求。 在创建部署过程中，环境变量（例如pods，services）从先前创建的configMaps和secrets中注入。 此部署使用在第一步中创建的映像kubernetesdemo / to-do-app-backend。 确保之前已创建configmap和密钥，否则请删除在部署对象期间创建的配置，创建configMap，密钥，然后再次运行部署配置文件。

如果得到另一种可能性：

com.mysql.cj.jdbc.exceptions.CommunicationsException：通信链接失败

错误，表示该数据库根本无法访问。 可能有以下一种或多种原因：

  1. JDBC URL中的IP地址或主机名错误。
  2. 本地DNS服务器无法识别JDBC URL中的主机名。
  3. JDBC URL中的端口号丢失或错误。 ~~ 4。 数据库服务器已关闭。~~
  4. DB服务器不接受TCP / IP连接。
  5. 数据库服务器已用尽连接。
  6. Java和DB之间的某种事物正在阻止连接，例如防火墙或代理。

我假设如果您的mysql pod正在运行，则您的数据库服务器正在运行，并指向~~ 4。 数据库服务器已关闭。~~错误。

要解决一个或另一个，请遵循以下建议：

使用ping验证并测试它们。 刷新DNS或在JDBC URL中使用IP地址。 检查它是否基于MySQL DB的my.cnf。 再次启动数据库。 检查mysqld是否在没有--skip-networking选项的情况下启动。 重新启动数据库，并相应地修复代码，以最终关闭连接。 禁用防火墙和/或配置防火墙/代理以允许/转发端口。

您可以在此处找到类似的错误： communication-error 。

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