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@ -3,31 +3,40 @@ title: 使用 Service 把前端连接到后端
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content_type: tutorial
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weight: 70
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---
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<!--
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title: Connect a Frontend to a Backend Using Services
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content_type: tutorial
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weight: 70
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-->
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<!-- overview -->
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<!--
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This task shows how to create a frontend and a backend
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microservice. The backend microservice is a hello greeter. The
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frontend and backend are connected using a Kubernetes
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{{< glossary_tooltip term_id="service" >}} object.
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This task shows how to create a _frontend_ and a _backend_ microservice. The backend
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microservice is a hello greeter. The frontend exposes the backend using nginx and a
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Kubernetes {{< glossary_tooltip term_id="service" >}} object.
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-->
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本任务会描述如何创建前端微服务和后端微服务。后端微服务是一个 hello 欢迎程序。
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前端和后端的连接是通过 Kubernetes {{< glossary_tooltip term_id="service" text="服务" >}}
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完成的。
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本任务会描述如何创建前端(Frontend)微服务和后端(Backend)微服务。后端微服务是一个 hello 欢迎程序。
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前端通过 nginx 和一个 Kubernetes {{< glossary_tooltip term_id="service" text="服务" >}}
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暴露后端所提供的服务。
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## {{% heading "objectives" %}}
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<!--
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* Create and run a microservice using a {{< glossary_tooltip term_id="deployment" >}} object.
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* Route traffic to the backend using a frontend.
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* Use a Service object to connect the frontend application to the
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backend application.
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* Create and run a sample `hello` backend microservice using a
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{{< glossary_tooltip term_id="deployment" >}} object.
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* Use a Service object to send traffic to the backend microservice's multiple replicas.
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* Create and run a `nginx` frontend microservice, also using a Deployment object.
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* Configure the frontend microservice to send traffic to the backend microservice.
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* Use a Service object of `type=LoadBalancer` to expose the frontend microservice
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outside the cluster.
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-->
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* 使用部署对象(Deployment object)创建并运行一个微服务
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* 从后端将流量路由到前端
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* 使用服务对象把前端应用连接到后端应用
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* 使用部署对象(Deployment object)创建并运行一个 `hello` 后端微服务
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* 使用一个 Service 对象将请求流量发送到后端微服务的多个副本
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* 同样使用一个 Deployment 对象创建并运行一个 `nginx` 前端微服务
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* 配置前端微服务将请求流量发送到后端微服务
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* 使用 `type=LoadBalancer` 的 Service 对象将全段微服务暴露到集群外部
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## {{% heading "prerequisites" %}}
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@ -39,8 +48,7 @@ This task uses
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require a supported environment. If your environment does not support this, you can use a Service of type
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[NodePort](/docs/concepts/services-networking/service/#nodeport) instead.
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-->
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本任务使用 [外部负载均衡服务](/zh/docs/tasks/access-application-cluster/create-external-load-balancer/),
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本任务使用[外部负载均衡服务](/zh/docs/tasks/access-application-cluster/create-external-load-balancer/),
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所以需要对应的可支持此功能的环境。如果你的环境不能支持,你可以使用
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[NodePort](/zh/docs/concepts/services-networking/service/#nodeport)
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类型的服务代替。
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@ -57,7 +65,7 @@ file for the backend Deployment:
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后端是一个简单的 hello 欢迎微服务应用。这是后端应用的 Deployment 配置文件:
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{{< codenew file="service/access/hello.yaml" >}}
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{{< codenew file="service/access/backend-deployment.yaml" >}}
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<!--
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Create the backend Deployment:
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@ -65,7 +73,7 @@ Create the backend Deployment:
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创建后端 Deployment:
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```shell
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kubectl apply -f https://k8s.io/examples/service/access/hello.yaml
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kubectl apply -f https://k8s.io/examples/service/access/backend-deployment.yaml
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```
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<!--
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@ -73,7 +81,7 @@ View information about the backend Deployment:
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-->
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查看后端的 Deployment 信息:
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```
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```shell
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kubectl describe deployment hello
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```
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@ -83,7 +91,7 @@ The output is similar to this:
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输出类似于:
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```
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Name: hello
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Name: backend
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Namespace: default
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CreationTimestamp: Mon, 24 Oct 2016 14:21:02 -0700
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Labels: app=hello
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@ -91,7 +99,7 @@ Labels: app=hello
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track=stable
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Annotations: deployment.kubernetes.io/revision=1
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Selector: app=hello,tier=backend,track=stable
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Replicas: 7 desired | 7 updated | 7 total | 7 available | 0 unavailable
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Replicas: 3 desired | 3 updated | 3 total | 3 available | 0 unavailable
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StrategyType: RollingUpdate
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MinReadySeconds: 0
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RollingUpdateStrategy: 1 max unavailable, 1 max surge
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@ -112,15 +120,15 @@ Conditions:
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Available True MinimumReplicasAvailable
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Progressing True NewReplicaSetAvailable
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OldReplicaSets: <none>
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NewReplicaSet: hello-3621623197 (7/7 replicas created)
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NewReplicaSet: hello-3621623197 (3/3 replicas created)
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Events:
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...
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```
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<!--
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## Creating the backend Service object
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## Creating the `hello` Service object
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The key to connecting a frontend to a backend is the backend
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The key to sending requests from a frontend to a backend is the backend
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Service. A Service creates a persistent IP address and DNS name entry
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so that the backend microservice can always be reached. A Service uses
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{{< glossary_tooltip text="selectors" term_id="selector" >}} to find
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@ -128,68 +136,84 @@ the Pods that it routes traffic to.
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First, explore the Service configuration file:
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-->
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### 创建后端服务对象
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### 创建 `hello` Service 对象
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前端连接到后端的关键是 Service(服务)。Service 创建一个固定 IP 和 DNS 解析名入口,
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使得后端微服务可达。Service 使用
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将请求从前端发送到到后端的关键是后端 Service。Service 创建一个固定 IP 和 DNS 解析名入口,
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使得后端微服务总是可达。Service 使用
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{{< glossary_tooltip text="选择算符" term_id="selector" >}}
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来寻找目标 Pod。
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首先,浏览 Service 的配置文件:
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{{< codenew file="service/access/hello-service.yaml" >}}
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{{< codenew file="service/access/backend-service.yaml" >}}
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<!--
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In the configuration file, you can see that the Service routes traffic to Pods
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that have the labels `app: hello` and `tier: backend`.
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In the configuration file, you can see that the Service named `hello` routes
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traffic to Pods that have the labels `app: hello` and `tier: backend`.
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-->
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配置文件中,你可以看到 Service 将流量路由到包含 `app: hello` 和 `tier: backend` 标签的 Pod。
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配置文件中,你可以看到名为 `hello` 的 Service 将流量路由到包含 `app: hello`
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和 `tier: backend` 标签的 Pod。
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<!--
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Create the `hello` Service:
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Create the backend Service:
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-->
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创建 `hello` Service:
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创建后端 Service:
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```shell
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kubectl apply -f https://k8s.io/examples/service/access/hello-service.yaml
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kubectl apply -f https://k8s.io/examples/service/access/backend-service.yaml
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```
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<!--
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At this point, you have a backend Deployment running, and you have a
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Service that can route traffic to it.
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At this point, you have a `backend` Deployment running three replicas of your `hello`
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application, and you have a Service that can route traffic to them. However, this
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service is neither available nor resolvable outside the cluster.
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-->
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此时,你已经有了一个在运行的后端 Deployment,你也有了一个 Service 用于路由网络流量。
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此时,你已经有了一个运行着 `hello` 应用的三个副本的 `backend` Deployment,你也有了
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一个 Service 用于路由网络流量。不过,这个服务在集群外部无法访问也无法解析。
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<!--
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## Creating the frontend
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Now that you have your backend, you can create a frontend that connects to the backend.
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The frontend connects to the backend worker Pods by using the DNS name
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given to the backend Service. The DNS name is "hello", which is the value
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of the `name` field in the preceding Service configuration file.
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Now that you have your backend running, you can create a frontend that is accessible
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outside the cluster, and connects to the backend by proxying requests to it.
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The frontend sends requests to the backend worker Pods by using the DNS name
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given to the backend Service. The DNS name is `hello`, which is the value
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of the `name` field in the `examples/service/access/backend-service.yaml`
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configuration file.
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The Pods in the frontend Deployment run an nginx image that is configured
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to find the hello backend Service. Here is the nginx configuration file:
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to proxy requests to the hello backend Service. Here is the nginx configuration file:
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-->
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### 创建前端应用
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既然你已经有了后端应用,你可以创建一个前端应用连接到后端。前端应用通过 DNS 名连接到后端的工作 Pods。
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DNS 名是 "hello",也就是 Service 配置文件中 `name` 字段的值。
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现在你已经有了运行中的后端应用,你可以创建一个可在集群外部访问的前端,并通过代理
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前端的请求连接到后端。
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前端 Deployment 中的 Pods 运行一个 nginx 镜像,这个已经配置好镜像去寻找后端的 hello Service。
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只是 nginx 的配置文件:
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前端使用被赋予后端 Service 的 DNS 名称将请求发送到后端工作 Pods。这一 DNS
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名称为 `hello`,也就是 `examples/service/access/backend-service.yaml` 配置
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文件中 `name` 字段的取值。
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{{< codenew file="service/access/frontend.conf" >}}
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前端 Deployment 中的 Pods 运行一个 nginx 镜像,这个已经配置好的镜像会将请求转发
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给后端的 hello Service。下面是 nginx 的配置文件:
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{{< codenew file="service/access/frontend-nginx.conf" >}}
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<!--
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Similar to the backend, the frontend has a Deployment and a Service. The
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configuration for the Service has `type: LoadBalancer`, which means that
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the Service uses the default load balancer of your cloud provider.
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Similar to the backend, the frontend has a Deployment and a Service. An important
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difference to notice between the backend and frontend services, is that the
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configuration for the frontend Service has `type: LoadBalancer`, which means that
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the Service uses a load balancer provisioned by your cloud provider and will be
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accessible from outside the cluster.
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-->
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与后端类似,前端用包含一个 Deployment 和一个 Service。Service 的配置文件包含了 `type: LoadBalancer`,
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也就是说,Service 会使用你的云服务商的默认负载均衡设备。
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与后端类似,前端用包含一个 Deployment 和一个 Service。后端与前端服务之间的一个
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重要区别是前端 Service 的配置文件包含了 `type: LoadBalancer`,也就是说,Service
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会使用你的云服务商的默认负载均衡设备,从而实现从集群外访问的目的。
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{{< codenew file="service/access/frontend-service.yaml" >}}
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{{< codenew file="service/access/frontend-deployment.yaml" >}}
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{{< codenew file="service/access/frontend.yaml" >}}
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<!--
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Create the frontend Deployment and Service:
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@ -197,7 +221,8 @@ Create the frontend Deployment and Service:
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创建前端 Deployment 和 Service:
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```shell
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kubectl apply -f https://k8s.io/examples/service/access/frontend.yaml
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kubectl apply -f https://k8s.io/examples/service/access/frontend-deployment.yaml
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kubectl apply -f https://k8s.io/examples/service/access/frontend-service.yaml
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```
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<!--
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@ -271,21 +296,22 @@ cluster.
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<!--
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## Send traffic through the frontend
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The frontend and backends are now connected. You can hit the endpoint
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The frontend and backend are now connected. You can hit the endpoint
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by using the curl command on the external IP of your frontend Service.
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-->
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### 通过前端发送流量
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前端和后端已经完成连接了。你可以使用 curl 命令通过你的前端 Service 的外部 IP 访问服务端点。
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前端和后端已经完成连接了。你可以使用 curl 命令通过你的前端 Service 的外部
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IP 访问服务端点。
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```shell
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curl http://<EXTERNAL-IP>
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curl http://${EXTERNAL_IP} # 将 EXTERNAL_P 替换为你之前看到的外部 IP
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```
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<!--
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The output shows the message generated by the backend:
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-->
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后端生成的消息输出如下:
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输出显示后端生成的消息:
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```json
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{"message":"Hello"}
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@ -299,7 +325,7 @@ To delete the Services, enter this command:
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要删除服务,输入下面的命令:
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```shell
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kubectl delete services frontend hello
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kubectl delete services frontend backend
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```
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<!--
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@ -308,14 +334,16 @@ To delete the Deployments, the ReplicaSets and the Pods that are running the bac
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要删除在前端和后端应用中运行的 Deployment、ReplicaSet 和 Pod,输入下面的命令:
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```shell
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kubectl delete deployment frontend hello
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kubectl delete deployment frontend backend
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```
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## {{% heading "whatsnext" %}}
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<!--
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* Learn more about [Services](/docs/concepts/services-networking/service/)
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* Learn more about [ConfigMaps](/docs/tasks/configure-pod-container/configure-pod-configmap/)
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* Learn more about [DNS for Service and Pods](/docs/concepts/services-networking/dns-pod-service/)
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-->
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* 进一步了解[Service](/zh/docs/concepts/services-networking/service/)
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* 进一步了解[ConfigMap](/zh/docs/tasks/configure-pod-container/configure-pod-configmap/)
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* 进一步了解 [Service](/zh/docs/concepts/services-networking/service/)
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* 进一步了解 [ConfigMap](/zh/docs/tasks/configure-pod-container/configure-pod-configmap/)
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* 进一步了解 [Service 和 Pods 的 DNS](/docs/concepts/services-networking/dns-pod-service/)
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