接下来的内容由以下几部分组成：
SpringCloud Gateway是SpringCloud技术栈下的网关服务框架，在基于SpringCloud的微服务环境中，外部请求会到达SpringCloud Gateway应用，该应用对请求做转发、过滤、鉴权、熔断等前置操作，一个典型的请求响应流程如下所示：
如果您之前没有使用过SpringCloud Gateway，推荐您阅读 《速体验SpringCloud Gateway》，有时间的话动手实战效果更佳，只需编写少量代码就能快速熟悉这个SpringCloud技术栈中非常重要的功能；
注意以下两个知识点：
将以上两个知识点结合起来，于是可以推测：运行在kubernetes环境的SpringCloud Gateway应用，如果使用了spring-cloud-kubernetes框架就能得到kubernetes的service列表，因此可以承担网关的角色，将外部请求转发至kubernetes内的service上，最终到达对应的Pod；
架构如下图所示，请注意黄色背景的对话框，里面标识了关键操作：
至此，理论分析已经完成，我们来实战验证这个理论，接下来我们开发两个java应用：
本次实战的环境和版本信息如下：
如果您不打算写代码，也可以从GitHub上下载本次实战的源码，地址和链接信息如下表所示：
| 名称 | 链接 | 备注 |
|---|---|---|
| 项目主页 | https://github.com/zq2599/blog_demos
| 该项目在GitHub上的主页 |
| git仓库地址(https) | https://github.com/zq2599/blog_demos.git | 该项目源码的仓库地址，https协议 |
| git仓库地址(ssh) | [email protected]:zq2599/blog_demos.git | 该项目源码的仓库地址，ssh协议 |
这个git项目中有多个文件夹，本章的两个应用分别在webdemo和k8sgatewaydemo文件夹下； 下图红框中是webdemo应用的源码：
下图红框中是k8sgatewaydemo应用的源码：
下面是详细的编码过程；
webdemo是个极其普通的spring boot应用，和SpringCloud没有任何关系；
@RestController
@RequestMapping("/hello")
public class HelloController {
@RequestMapping(value = "time", method = RequestMethod.GET)
public String hello(HttpServletRequest request){
return "hello, "
+ new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date())
+ ", extendtag ["
+ request.getHeader("extendtag")
+ "]";
}
} @SpringBootApplication
public class WebdemoApplication {
public static void main(String[] args) {
SpringApplication.run(WebdemoApplication.class, args);
}
} <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.bolingcavalry</groupId>
<artifactId>webdemo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>webdemo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
<spring-boot.version>2.1.6.RELEASE</spring-boot.version>
<fabric8.maven.plugin.version>3.5.37</fabric8.maven.plugin.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>${spring-boot.version}</version>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<!--skip deploy -->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-deploy-plugin</artifactId>
<version>${maven-deploy-plugin.version}</version>
<configuration>
<skip>true</skip>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>${maven-surefire-plugin.version}</version>
<configuration>
<skipTests>true</skipTests>
<!-- Workaround for https://issues.apache.org/jira/browse/SUREFIRE-1588 -->
<useSystemClassLoader>false</useSystemClassLoader>
</configuration>
</plugin>
<plugin>
<groupId>io.fabric8</groupId>
<artifactId>fabric8-maven-plugin</artifactId>
<version>${fabric8.maven.plugin.version}</version>
<executions>
<execution>
<id>fmp</id>
<goals>
<goal>resource</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
<profiles>
<profile>
<id>kubernetes</id>
<build>
<plugins>
<plugin>
<groupId>io.fabric8</groupId>
<artifactId>fabric8-maven-plugin</artifactId>
<version>${fabric8.maven.plugin.version}</version>
<executions>
<execution>
<id>fmp</id>
<goals>
<goal>resource</goal>
<goal>build</goal>
</goals>
</execution>
</executions>
<configuration>
<enricher>
<config>
<fmp-service>
<type>NodePort</type>
</fmp-service>
</config>
</enricher>
</configuration>
</plugin>
</plugins>
</build>
</profile>
</profiles>
</project> mvn clean install fabric8:deploy -Dfabric8.generator.from=fabric8/java-jboss-openjdk8-jdk -Pkubernetes
部署完成后终端输出类似如下成功信息：
[INFO] [INFO] <<< fabric8-maven-plugin:3.5.37:deploy (default-cli) < install @ webdemo <<< [INFO] [INFO] [INFO] --- fabric8-maven-plugin:3.5.37:deploy (default-cli) @ webdemo --- [INFO] F8: Using Kubernetes at https://192.168.121.133:8443/ in namespace default with manifest /usr/local/work/k8s/webdemo/target/classes/META-INF/fabric8/kubernetes.yml [INFO] Using namespace: default [INFO] Updating a Service from kubernetes.yml [INFO] Updated Service: target/fabric8/applyJson/default/service-webdemo.json [INFO] Using namespace: default [INFO] Updating Deployment from kubernetes.yml [INFO] Updated Deployment: target/fabric8/applyJson/default/deployment-webdemo.json [INFO] F8: HINT: Use the command `kubectl get pods -w` to watch your pods start up [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 11.804 s [INFO] Finished at: 2019-07-07T21:32:26+08:00 [INFO] ------------------------------------------------------------------------
[root@minikube webdemo]# kubectl get service NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 29d webdemo NodePort 10.106.98.137 <none> 8080:30160/TCP 115m [root@minikube webdemo]# kubectl get pod NAME READY STATUS RESTARTS AGE webdemo-c9f774b9-gsbgx 1/1 Running 0 3m13s
[root@minikube webdemo]# minikube service webdemo --url http://192.168.121.133:30160
可见外部通过地址： http://192.168.121.133:30160即可访问到webdemo应用； 7. 在浏览器输入地址： http://192.168.121.133:30160/hello/time，即可验证webdemo的http接口是否正常，如下图，由于header中没有extendtag属性，因此返回的extendtag为null：
至此，webdemo在minikue上已经正常运行，该开发gateway应用了；
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.bolingcavalry</groupId>
<artifactId>k8sgatewaydemo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>k8sgatewaydemo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
<spring-boot.version>2.1.6.RELEASE</spring-boot.version>
<maven-checkstyle-plugin.failsOnError>false</maven-checkstyle-plugin.failsOnError>
<maven-checkstyle-plugin.failsOnViolation>false</maven-checkstyle-plugin.failsOnViolation>
<maven-checkstyle-plugin.includeTestSourceDirectory>false</maven-checkstyle-plugin.includeTestSourceDirectory>
<maven-compiler-plugin.version>3.5</maven-compiler-plugin.version>
<maven-deploy-plugin.version>2.8.2</maven-deploy-plugin.version>
<maven-failsafe-plugin.version>2.18.1</maven-failsafe-plugin.version>
<maven-surefire-plugin.version>2.21.0</maven-surefire-plugin.version>
<fabric8.maven.plugin.version>3.5.37</fabric8.maven.plugin.version>
<springcloud.kubernetes.version>1.0.1.RELEASE</springcloud.kubernetes.version>
<spring-cloud.version>Greenwich.SR2</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-kubernetes-core</artifactId>
<version>${springcloud.kubernetes.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-kubernetes-discovery</artifactId>
<version>${springcloud.kubernetes.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-kubernetes-ribbon</artifactId>
<version>${springcloud.kubernetes.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-commons</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>${spring-boot.version}</version>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<!--skip deploy -->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-deploy-plugin</artifactId>
<version>${maven-deploy-plugin.version}</version>
<configuration>
<skip>true</skip>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>${maven-surefire-plugin.version}</version>
<configuration>
<skipTests>true</skipTests>
<!-- Workaround for https://issues.apache.org/jira/browse/SUREFIRE-1588 -->
<useSystemClassLoader>false</useSystemClassLoader>
</configuration>
</plugin>
<plugin>
<groupId>io.fabric8</groupId>
<artifactId>fabric8-maven-plugin</artifactId>
<version>${fabric8.maven.plugin.version}</version>
<executions>
<execution>
<id>fmp</id>
<goals>
<goal>resource</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
<profiles>
<profile>
<id>kubernetes</id>
<build>
<plugins>
<plugin>
<groupId>io.fabric8</groupId>
<artifactId>fabric8-maven-plugin</artifactId>
<version>${fabric8.maven.plugin.version}</version>
<executions>
<execution>
<id>fmp</id>
<goals>
<goal>resource</goal>
<goal>build</goal>
</goals>
</execution>
</executions>
<configuration>
<enricher>
<config>
<fmp-service>
<type>NodePort</type>
</fmp-service>
</config>
</enricher>
</configuration>
</plugin>
</plugins>
</build>
</profile>
</profiles>
</project> 上述pom文件中有以下几点需要注意： 第一、 依赖spring-cloud-kubernetes-core和spring-cloud-kubernetes-discovery，这样能用到spring-cloud-kubernetes提供的服务发现能力； 第二、依赖spring-cloud-starter-gateway，这样能用上SpringCloud的gateway能力； 第三、不要依赖spring-boot-starter-web，会和spring-cloud-starter-gateway冲突，启动时抛出以下异常：
2019-07-06 08:12:09.188 WARN 1 --- [ main] ConfigServletWebServerApplicationContext :
Exception encountered during context initialization -
cancelling refresh attempt:
org.springframework.beans.factory.UnsatisfiedDependencyException:
Error creating bean with name 'routeDefinitionRouteLocator' defined in class path resource [org/springframework/cloud/gateway/config/GatewayAutoConfiguration.class]:
Unsatisfied dependency expressed through method 'routeDefinitionRouteLocator' parameter 1;
nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException:
Error creating bean with name 'modifyRequestBodyGatewayFilterFactory' defined in class path resource [org/springframework/cloud/gateway/config/GatewayAutoConfiguration.class]:
Unsatisfied dependency expressed through method 'modifyRequestBodyGatewayFilterFactory' parameter 0;
nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.http.codec.ServerCodecConfigurer' available:
expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {} @SpringBootApplication
@EnableDiscoveryClient
public class K8sgatewaydemoApplication {
public static void main(String[] args) {
SpringApplication.run(K8sgatewaydemoApplication.class, args);
}
@Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder) {
return builder.routes()
//增加一个path匹配，以"/customize/hello/"开头的请求都在此路由
.route(r -> r.path("/customize/hello/**")
//表示将路径中的第一级参数删除，用剩下的路径与webdemo的路径做拼接，
//这里就是"lb://webdemo/hello/"，能匹配到webdemo的HelloController的路径
.filters(f -> f.stripPrefix(1)
//在请求的header中添加一个key&value
.addRequestHeader("extendtag", "geteway-" + System.currentTimeMillis()))
//指定匹配服务webdemo，lb是load balance的意思
.uri("lb://webdemo")
).build();
}
} 从上述代码可见，K8sgatewaydemoApplication与普通环境下的SpringCloud Gateway并无差别，都是通过EnableDiscoveryClient注解获取服务列表，配置RouteLocator实现路由逻辑； 3. 配置文件application.yml的内容：
spring:
application:
name: gateway
cloud:
gateway:
discovery:
locator:
enabled: true
lowerCaseServiceId: true mvn clean install fabric8:deploy -Dfabric8.generator.from=fabric8/java-jboss-openjdk8-jdk -Pkubernetes
部署完成后终端输出类似如下成功信息：
[INFO] [INFO] <<< fabric8-maven-plugin:3.5.37:deploy (default-cli) < install @ k8sgatewaydemo <<< [INFO] [INFO] [INFO] --- fabric8-maven-plugin:3.5.37:deploy (default-cli) @ k8sgatewaydemo --- [INFO] F8: Using Kubernetes at https://192.168.121.133:8443/ in namespace default with manifest /usr/local/work/k8s/k8sgatewaydemo/target/classes/META-INF/fabric8/kubernetes.yml [INFO] Using namespace: default [INFO] Updating a Service from kubernetes.yml [INFO] Updated Service: target/fabric8/applyJson/default/service-k8sgatewaydemo.json [INFO] Using namespace: default [INFO] Updating Deployment from kubernetes.yml [INFO] Updated Deployment: target/fabric8/applyJson/default/deployment-k8sgatewaydemo.json [INFO] F8: HINT: Use the command `kubectl get pods -w` to watch your pods start up [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 16.538 s [INFO] Finished at: 2019-07-07T22:04:48+08:00 [INFO] ------------------------------------------------------------------------
[root@minikube k8sgatewaydemo]# clear [root@minikube k8sgatewaydemo]# kubectl get service NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE k8sgatewaydemo NodePort 10.97.94.238 <none> 8080:31352/TCP 129m kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 29d webdemo NodePort 10.106.98.137 <none> 8080:30160/TCP 145m [root@minikube k8sgatewaydemo]# kubectl get pod NAME READY STATUS RESTARTS AGE k8sgatewaydemo-6fbb79885c-r2jfn 1/1 Running 0 33s webdemo-c9f774b9-gsbgx 1/1 Running 0 32m
[root@minikube k8sgatewaydemo]# minikube service k8sgatewaydemo --url http://192.168.121.133:31352
可见外部通过地址： http://192.168.121.133:31352即可访问到k8sgatewaydemo应用； 7. 在浏览器输入地址： http://192.168.121.133:31352/customize/hello/time，即可验证k8sgatewaydemo作为网关应用，能否将路径中带有customize的请求转发到webdemo应用，并且在请求header中添加名为entendtag的属性，如下图，浏览器展示的内容是webdemo的http接口返回的，并且extendtag的内容也不为空了，而是k8sgatewaydemo在转发前写入的：
上述结果表明已可以证明我们之前的推测是正确的：SpringCloud Gateway应用在使用了spring-cloud-kubernetes提供的注册发现能力后，可以将请求转发到kubernetes环境中的服务上； 也就是说，借助spring-cloud-kubernetes框架，你在SpringCloud环境开发的SpringCloud Gateway应用，可以以很小的代价迁移到kubernetes环境，与kubernetes环境中的service可以很好的交互，而原有的eureka注册中心也可以不用了；
如果您的spring-cloud-kubernetes在向webdemo转发请求时抛出以下错误，那是因为遇到了kubernetes的权限问题：
2019-07-06 04:46:40.042 WARN 1 --- [erListUpdater-1] c.n.l.PollingServerListUpdater : Failed one update cycle
io.fabric8.kubernetes.client.KubernetesClientException: Failure executing: GET at: https://10.96.0.1/api/v1/namespaces/default/endpoints/account-service. Message: Forbidden!Configured service account doesn't have access. Service account may have been revoked. endpoints "account-service" is forbidden: User "system:serviceaccount:default:default" cannot get resource "endpoints" in API group "" in the namespace "default".
at io.fabric8.kubernetes.client.dsl.base.OperationSupport.requestFailure(OperationSupport.java:476) ~[kubernetes-client-4.1.0.jar!/:na]
at io.fabric8.kubernetes.client.dsl.base.OperationSupport.assertResponseCode(OperationSupport.java:413) ~[kubernetes-client-4.1.0.jar!/:na]
at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleResponse(OperationSupport.java:381) ~[kubernetes-client-4.1.0.jar!/:na]
at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleResponse(OperationSupport.java:344) ~[kubernetes-client-4.1.0.jar!/:na]
at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleGet(OperationSupport.java:313) ~[kubernetes-client-4.1.0.jar!/:na]
at io.fabric8.kubernetes.client.dsl.base.OperationSupport.handleGet(OperationSupport.java:296) ~[kubernetes-client-4.1.0.jar!/:na]
at io.fabric8.kubernetes.client.dsl.base.BaseOperation.handleGet(BaseOperation.java:794) ~[kubernetes-client-4.1.0.jar!/:na]
at io.fabric8.kubernetes.client.dsl.base.BaseOperation.getMandatory(BaseOperation.java:210) ~[kubernetes-client-4.1.0.jar!/:na]
at io.fabric8.kubernetes.client.dsl.base.BaseOperation.get(BaseOperation.java:177) ~[kubernetes-client-4.1.0.jar!/:na]
at org.springframework.cloud.kubernetes.ribbon.KubernetesServerList
.getUpdatedListOfServers(KubernetesServerList.java:75) ~[spring-cloud-kubernetes-ribbon-1.0.1.RELEASE.jar!/:1.0.1.RELEASE]
at com.netflix.loadbalancer.DynamicServerListLoadBalancer.updateListOfServers(DynamicServerListLoadBalancer.java:240) ~[ribbon-loadbalancer-2.3.0.jar!/:2.3.0]
at com.netflix.loadbalancer.DynamicServerListLoadBalancer$1.doUpdate(DynamicServerListLoadBalancer.java:62) ~[ribbon-loadbalancer-2.3.0.jar!/:2.3.0]
at com.netflix.loadbalancer.PollingServerListUpdater$1.run(PollingServerListUpdater.java:116) ~[ribbon-loadbalancer-2.3.0.jar!/:2.3.0]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_191]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) [na:1.8.0_191]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_191]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) [na:1.8.0_191]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_191]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_191]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191] 处理方法是创建ServiceAccount对象，步骤如下：
# NOTE: The service account `default:default` already exists in k8s cluster.
# You can create a new account following like this:
#---
#apiVersion: v1
#kind: ServiceAccount
#metadata:
# name: <new-account-name>
# namespace: <namespace>
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
name: fabric8-rbac
subjects:
- kind: ServiceAccount
# Reference to upper's `metadata.name`
name: default
# Reference to upper's `metadata.namespace`
namespace: default
roleRef:
kind: ClusterRole
name: cluster-admin
apiGroup: rbac.authorization.k8s.io kubectl apply -f fabric8-rbac.yaml
再回顾一下k8sgatewaydemo的开发过程，您会发现除了依赖spring-cloud-kubernetes对应的maven库，我们并没有显式调用spring-cloud-kubernetes相关的API或者做相关配置，就获取了所在kubernetes环境的原生服务，这是怎么回事呢？为何成本如此的低？ 答案就在 《spring-cloud-kubernetes背后的三个关键知识点》一文中，推荐您回顾一下此文。
至此，spring-cloud-kubernetes框架下的SpringCloud Gateway开发实战就完成了，希望本文能帮助您更好的理解和使用spring-cloud-kubernetes，更加高效的将应用向容器化迁移。