从 Kubernetes 中的另一个服务访问服务答案

【问题标题】：Accessing service from another service in Kubernetes从 Kubernetes 中的另一个服务访问服务
【发布时间】：2020-11-27 06:46:51
【问题描述】：

我有一个 Spring Boot 服务，我想连接到 Kubernetes 中的 mongodb。到目前为止，我已经构建了应用程序的 docker 映像并创建了 Kubernetes 部署，在同一个部署 YAML 文件中指定了应用程序和 mongodb 的映像。另外，我为该应用创建了一个服务 YAML，它运行良好。

deployment.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: springbootmongodb
  labels:
    app: springbootmongodb
spec:
  replicas: 1
  selector:
    matchLabels:
      app: springbootmongodb
  template:
    metadata:
      labels:
        app: springbootmongodb
    spec:
      containers:
      - name: springbootmongodb
        image: mytest/springbootmongodb
      - name: mongo
        image: mongo

--service.yaml

apiVersion: v1
kind: Service
metadata:
  name: springbootmongodb
  labels:
    app: springbootmongodb
spec:
  type: ClusterIP
  ports:
  - name: 8080-8080
    port: 8080
    targetPort: 8080
    protocol: TCP
  selector:
    app: springbootmongodb

端口转发命令：

kubectl port-forward svc/springbootmongodb 8080:8080

一切都适用于上述配置。

现在，我想为应用创建单独的部署并创建两个部署和服务 YAML，但它不起作用。有人可以帮帮我吗？

应用部署.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: springbootmongodb
  labels:
    app: springbootmongodb
spec:
  replicas: 1
  selector:
    matchLabels:
      app: springbootmongodb
  template:
    metadata:
      labels:
        app: springbootmongodb
    spec:
      containers:
      - name: springbootmongodb
        image: mytest/springbootmongodb

mongo-deployment.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb
  labels:
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mongo
  template:
    metadata:
      labels:
        app: mongo
    spec:
      containers:
        - name: mongo
          image: mongo
          ports:
            - containerPort: 27017

appservice.yml

apiVersion: v1
kind: Service
metadata:
  name: springbootmongodb
  labels:
    app: springbootmongodb
spec:
  type: NodePort
  ports:
  - name: 8080-8080
    port: 8080
    targetPort: 8080
    protocol: TCP
  selector:
    app: springbootmongodb

mongoservice.yml

apiVersion: v1
kind: Service
metadata:
  name: mongodb
  labels:
    app: mongo
spec:
  type: ClusterIP
  ports:
    - port: 27017
      targetPort: 27017
      protocol: TCP
  selector:
    app: mongo

我看到所有创建的对象：

kubectl 获取 pod 名称就绪状态重新开始年龄 mongodb-686dd5cb7f-dr9hq 1/1 运行 0 3m12s springbootmongodb-7ccbc488fb-vtgw5 1/1 运行 0 115s

kubectl 全部获取

NAME                                     READY   STATUS    RESTARTS   AGE
pod/mongodb-686dd5cb7f-dr9hq             1/1     Running   0          3m16s
pod/springbootmongodb-7ccbc488fb-vtgw5   1/1     Running   0          119s

NAME                        TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
service/kubernetes          ClusterIP   10.96.0.1       <none>        443/TCP          59d
service/mongodb             ClusterIP   10.111.83.192   <none>        27017/TCP        2m35s
service/springbootmongodb   NodePort    10.103.18.137   <none>        8080:31015/TCP   8s

NAME                                READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/mongodb             1/1     1            1           3m16s
deployment.apps/springbootmongodb   1/1     1            1           119s

NAME                                           DESIRED   CURRENT   READY   AGE
replicaset.apps/mongodb-686dd5cb7f             1         1         1       3m16s
replicaset.apps/springbootmongodb-7ccbc488fb   1         1         1       119s

服务错误日志：

2020-08-06 23:19:01.526  INFO 1 --- [nio-8080-exec-8] org.mongodb.driver.cluster               : Cluster description not yet available. Waiting for 30000 ms before timing out
2020-08-06 23:19:07.048 ERROR 1 --- [nio-8080-exec-7] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.DataAccessResourceFailureException: Timed out after 30000 ms while waiting to connect. Client view of cluster state is {type=UNKNOWN, servers=[{address=localhost:27017, type=UNKNOWN, state=CONNECTING, exception={com.mongodb.MongoSocketOpenException: Exception opening socket}, caused by {java.net.ConnectException: Connection refused (Connection refused)}}]; nested exception is com.mongodb.MongoTimeoutException: Timed out after 30000 ms while waiting to connect. Client view of cluster state is {type=UNKNOWN, servers=[{address=localhost:27017, type=UNKNOWN, state=CONNECTING, exception={com.mongodb.MongoSocketOpenException: Exception opening socket}, caused by {java.net.ConnectException: Connection refused (Connection refused)}}]] with root cause

com.mongodb.MongoTimeoutException: Timed out after 30000 ms while waiting to connect. Client view of cluster state is {type=UNKNOWN, servers=[{address=localhost:27017, type=UNKNOWN, state=CONNECTING, exception={com.mongodb.MongoSocketOpenException: Exception opening socket}, caused by {java.net.ConnectException: Connection refused (Connection refused)}}]
        at com.mongodb.internal.connection.BaseCluster.getDescription(BaseCluster.java:179) ~[mongodb-driver-core-3.8.2.jar!/:na]
        at com.mongodb.internal.connection.SingleServerCluster.getDescription(SingleServerCluster.java:41) ~[mongodb-driver-core-3.8.2.jar!/:na]
        at com.mongodb.client.internal.MongoClientDelegate.getConnectedClusterDescription(MongoClientDelegate.java:136) ~[mongodb-driver-3.8.2.jar!/:na]
        at com.mongodb.client.internal.MongoClientDelegate.createClientSession(MongoClientDelegate.java:94) ~[mongodb-driver-3.8.2.jar!/:na]
        at com.mongodb.client.internal.MongoClientDelegate$DelegateOperationExecutor.getClientSession(MongoClientDelegate.java:249) ~[mongodb-driver-3.8.2.jar!/:na]
        at com.mongodb.client.internal.MongoClientDelegate$DelegateOperationExecutor.execute(MongoClientDelegate.java:172) ~[mongodb-driver-3.8.2.jar!/:na]
        at com.mongodb.client.internal.MongoIterableImpl.execute(MongoIterableImpl.java:132) ~[mongodb-driver-3.8.2.jar!/:na]
        at com.mongodb.client.internal.MongoIterableImpl.iterator(MongoIterableImpl.java:86) ~[mongodb-driver-3.8.2.jar!/:na]
        at org.springframework.data.mongodb.core.MongoTemplate.executeFindMultiInternal(MongoTemplate.java:2643) ~[spring-data-mongodb-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.mongodb.core.MongoTemplate.doFind(MongoTemplate.java:2380) ~[spring-data-mongodb-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.mongodb.core.MongoTemplate.doFind(MongoTemplate.java:2363) ~[spring-data-mongodb-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.mongodb.core.MongoTemplate.find(MongoTemplate.java:820) ~[spring-data-mongodb-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.mongodb.repository.support.SimpleMongoRepository.findAll(SimpleMongoRepository.java:360) ~[spring-data-mongodb-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.mongodb.repository.support.SimpleMongoRepository.findAll(SimpleMongoRepository.java:194) ~[spring-data-mongodb-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.mongodb.repository.support.SimpleMongoRepository.findAll(SimpleMongoRepository.java:51) ~[spring-data-mongodb-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_212]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_212]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_212]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_212]
        at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:359) ~[spring-data-commons-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:200) ~[spring-data-commons-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:644) ~[spring-data-commons-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.2.RELEASE.jar!/:5.1.2.RELEASE]
        at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:608) ~[spring-data-commons-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$invoke$3(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.2.RELEASE.jar!/:5.1.2.RELEASE]
        at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59) ~[spring-data-commons-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.2.RELEASE.jar!/:5.1.2.RELEASE]
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) ~[spring-aop-5.1.2.RELEASE.jar!/:5.1.2.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.2.RELEASE.jar!/:5.1.2.RELEASE]
        at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61) ~[spring-data-commons-2.1.2.RELEASE.jar!/:2.1.2.RELEASE]

【问题讨论】：

(a) 不要将Deployment 用于数据库；这是个坏消息（b）你没有为 mongo 发布日志（甚至kubectl get pods）；如果 mongo 不存在，这是没有人可以连接到它的一个很好的理由
只是想了解为什么 mongo 的部署不好？服务够吗？

标签： mongodb spring-boot kubernetes

【解决方案1】：

看起来您需要更改 Springboot 应用程序的配置以使用 mongodb 端点：mongodb:27017 而不是 localhost:27017❓?。由于 mongo 不再在同一个容器/pod 上运行。

In the application.properties file something like this:

spring.data.mongodb.uri=mongodb://mongodb:27017/<dbname>

✌️

【讨论】：

谢谢，设置 env 变量成功了！在 spring 应用程序的部署 yml 中添加了这一点。还用所有 k8s 对象更新了我的帖子

【解决方案2】：

就像 Rico 已经提到你在配置文件中的地址错误。

请注意，还有其他问题，您可能也想解决。

您应该使用 Kubernetes StatefulSet 而不是 Deployment，因为它们是为考虑状态的工作负载而设计的，并且它们具有更好的状态和身份管理，这意味着可以更好地管理您的有状态数据。

当您为 MongoDB 部署创建超过 1 个副本时会出现主要问题，所有部署都将指向同一个 PV（持久卷），这可能会由于许多工作负载更改同一卷而导致数据不一致。

StatefulSet 将为每个副本创建一个 PV。那么您将有两个具有不同数据的数据库仍然存在不一致问题。

如果您正在构建企业应用程序，那么最好在 Kubernetes 之外实现您的数据库；这样一来，您的 Kubernetes 集群就会变得短暂且不包含任何状态，如果您的集群发生问题，您可以启动另一个集群。

如果您想在 k8s 集群中为企业应用程序实现数据库，您仍然必须使用具有主/从架构和复制管理器的多个副本来实现它。

MongoDB 实现了一个运算符来帮助您管理此问题Here is a Link。

另外值得一提的是，您没有使用环境变量将凭据/地址传递给您的数据库。将配置与工作负载分开通常是一种很好的做法，这样您就不必为您拥有的每个环境（例如 dev staging prod）更改部署文件。

【讨论】：