在阅读本文前,建议先阅读《spring cloud alibaba | sentinel:分布式系统的流量防卫兵基础实战》。
sentinel目前已经同时支持feign和resttemplate,需要我们引入对应的依赖,在使用feign的时候需要在配置文件中打开sentinel对feign的支持:feign.sentinel.enabled=true
,同时需要加入openfeign starter
依赖使sentinel starter
中的自动化配置类生效。在使用resttemplate的时候需要在构造resttemplate的bean的时候加上@sentinelresttemplate
注解,开启sentinel对resttemplate的支持。
父工程pom.xml如下:
代码清单:alibaba/sentinel-springcloud-high/pom.xml
***
<dependency> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-actuator</artifactid> </dependency> <dependency> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-web</artifactid> </dependency> <dependency> <groupid>com.alibaba.cloud</groupid> <artifactid>spring-cloud-starter-alibaba-sentinel</artifactid> </dependency> <dependency> <groupid>com.alibaba.cloud</groupid> <artifactid>spring-cloud-starter-alibaba-nacos-discovery</artifactid> </dependency>
公共组件中引入sentinel做流量控制,引入nacos做服务中心。
配置文件application.yml如下:
代码清单:alibaba/sentinel-springcloud-high/provider_server/pom.xml
***
server: port: 8000 spring: application: name: spring-cloud-provider-server cloud: nacos: discovery: server-addr: 192.168.44.129:8848 sentinel: transport: dashboard: localhost:8080 port: 8720 management: endpoints: web: cors: allowed-methods: '*'
接口测试类hellocontroller.java如下:
代码清单:alibaba/sentinel-springcloud-high/provider_server/src/main/java/com/springcloud/provider_server/controller/hellocontroller.java
***
@restcontroller public class hellocontroller { @getmapping("/hello") public string hello(httpservletrequest request) { return "hello, port is: " + request.getlocalport(); } }
子工程依赖pom.xml如下:
代码清单:alibaba/sentinel-springcloud-high/consumer_server/pom.xml
***
<dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-openfeign</artifactid> </dependency>
配置文件application.yml如下:
代码清单:alibaba/sentinel-springcloud-high/consumer_server/src/main/resources/application.yml
***
server: port: 9000 spring: application: name: spring-cloud-consumer-server cloud: nacos: discovery: server-addr: 192.168.44.129:8848 sentinel: transport: dashboard: localhost:8080 port: 8719 management: endpoints: web: cors: allowed-methods: '*' feign: sentinel: enabled: true
这里使用feign.sentinel.enabled=true
开启sentinel对feign的支持。
接口测试类hellocontroller.java
代码清单:alibaba/sentinel-springcloud-high/consumer_server/src/main/java/com/springcloud/consumer_server/controller/hellocontroller.java
***
@restcontroller public class hellocontroller { @autowired helloremote helloremote; @autowired resttemplate resttemplate; @getmapping("/hellobyfeign") public string hellobyfeign() { return helloremote.hello(); } @getmapping("/hellobyresttemplate") public string hellobyresttemplate() { return resttemplate.getforobject("http://spring-cloud-provider-server/hello/", string.class); } }
sentinel已经对做了整合,我们使用feign的地方无需额外的注解。同时,@feignclient
注解中的所有属性,sentinel都做了兼容。
启动主类ch122consumerserverapplication.java如下:
代码清单:alibaba/sentinel-springcloud-high/consumer_server/src/main/java/com/springcloud/consumer_server/consumerserverapplication.java
***
@springbootapplication @enablediscoveryclient @enablefeignclients public class ch122consumerserverapplication { public static void main(string[] args) { springapplication.run(ch122consumerserverapplication.class, args); } @bean @loadbalanced @sentinelresttemplate public resttemplate resttemplate() { return new resttemplate(); } }
在使用resttemplate的时候需要增加@sentinelresttemplate
来开启sentinel对resttemplate的支持。
启动工程provider_server和consumer_server,provider_server修改启动配置,启动两个实例,打开浏览器访问:http://www.lhsxpumps.com/_localhost:9000/hellobyfeign 和 http://localhost:9000/hellobyresttemplate ,刷新几次,可以看到页面交替显示hello, port is: 8000
和hello, port is: 8001
,说明目前负载均衡正常,现在查看sentinel控制台,如图:
这时选择左侧的簇点流控,点击流控,如图:
这里我们配置一个最简单的规则,配置qps限制为1,点击新增,如图:
这里解释一下什么是qps,简单来说qps是一个每秒访问数,这里我们测试时需要重复快速刷新http://www.lhsxpumps.com/_localhost:9000/hellobyfeign 和 http://localhost:9000/hellobyresttemplate ,在刷新的过程中,我们可以看到页面会显示错误信息,如:blocked by sentinel (flow limiting)
,说明我们配置sentinel已经限流成功,这时我们再看一下sentinel的控制台,可以看到我们刚才访问的成功和限流的数量,如图:
在上一小结,我们介绍了feign和resttemplate整合sentinel使用,并且在sentinel控制台上做了qps限流,并且限流成功,限流成功后,默认情况下,sentinel对控制资源的限流处理是直接抛出异常。在没有合理的业务承接或者前端对接情况下可以这样,但是正常情况为了更好的用户业务,都会实现一些被限流之后的特殊处理,我们不希望展示一个生硬的报错。这一小节,我们介绍一下服务降级处理。
feign服务降级类helloremotefallback.java如下:
代码清单:alibaba/sentinel-springcloud-high/consumer_fallback/src/main/java/com/springcloud/consumer_fallback/fallback/helloremotefallback.java
***
@component public class helloremotefallback implements helloremote { @override public string hello() { return "feign fallback msg"; } }
相对应的,这里需要在helloremote.java上做一部分配置,使得限流后,触发服务降级执行我们的服务降级类,代码如下:
代码清单:ch12_2/ch12_2_consumer_fallback/src/main/java/com/springcloud/book/ch12_2_consumer_fallback/remote/helloremote.java
***
@feignclient(name = "spring-cloud-provider-server", fallback = helloremotefallback.class) public interface helloremote { @getmapping("/hello") string hello(); }
fallback = helloremotefallback.class
指定服务降级的处理类为helloremotefallback.class
。
resttemplate服务降级工具类exceptionutil.java如下:
代码清单:alibaba/sentinel-springcloud-high/consumer_fallback/src/main/java/com/springcloud/consumer_fallback/remote/helloremote.java
***
public class exceptionutil { private final static logger logger = loggerfactory.getlogger(exceptionutil.class); public static sentinelclienthttpresponse handleexception(httprequest request, byte[] body, clienthttprequestexecution execution, blockexception ex) { logger.error(ex.getmessage(), ex); return new sentinelclienthttpresponse("resttemplate fallback msg"); } }
这里同样需要修改resttemplate注册成为bean的地方,使得resttemplate触发服务降级以后代码执行我们为它写的处理类,ch122consumerfallbackapplication.java代码如下:
代码清单:alibaba/sentinel-springcloud-high/consumer_fallback/src/main/java/com/springcloud/consumer_fallback/consumerfallbackapplication.java
***
@bean @loadbalanced @sentinelresttemplate(blockhandler = "handleexception", blockhandlerclass = exceptionutil.class) public resttemplate resttemplate() { return new resttemplate(); }
这里需要注意,@sentinelresttemplate
注解的属性支持限流(blockhandler
, blockhandlerclass
)和降级(fallback
, fallbackclass
)的处理。
其中blockhandler
或fallback
属性对应的方法必须是对应blockhandlerclass
或fallbackclass
属性中的静态方法。
@sentinelresttemplate
注解的限流(blockhandler
, blockhandlerclass
)和降级(fallback
, fallbackclass
)属性不强制填写。
当使用resttemplate调用被sentinel熔断后,会返回resttemplate request block by sentinel
信息,或者也可以编写对应的方法自行处理返回信息。这里提供了 sentinelclienthttpresponse
用于构造返回信息。
顺次启动provider_server和consumer_fallback两个子工程。先在浏览器中交替访问http://www.lhsxpumps.com/_localhost:9090/hellobyfeign 和 http://localhost:9090/hellobyresttemplate ,而后打开sentinel控制台,在这两个接口上增加限流信息,注意,这里要将限流信息加在资源上,具体如图:
在浏览器中刷新两个链接,两个限流信息都可以正常浏览器中显示,测试成功,再次查看sentinel控制台,也可以看到被拒接的流量统计,如图:
sentinel目前支持spring cloud gateway、zuul 等主流的 api gateway 进行限流。看一下官方的结构图,如图:
从这张官方的图中,可以看到,sentinel对zuul的限流主要是通过3个filter来完成的,对spring cloud gateway则是通过一个sentinlegatewayfilter
和一个blockrequesthandler
来完成的。
sentinel 1.6.0 引入了 sentinel api gateway adapter common 模块,此模块中包含网关限流的规则和自定义 api 的实体和管理逻辑:
sentinel 提供了 zuul 1.x 的适配模块,可以为 zuul gateway 提供两种资源维度的限流:
工程依赖pom.xml如下:
代码清单:alibaba/sentinel-springcloud-high/zuul_server/pom.xml
***
<dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-netflix-zuul</artifactid> </dependency> <dependency> <groupid>com.alibaba.csp</groupid> <artifactid>sentinel-zuul-adapter</artifactid> </dependency>
这里因为sentinel-zuul-adapter
未包含在spring-cloud-starter-alibaba-sentinel
,需要手动单独引入。
代码清单:alibaba/sentinel-springcloud-high/zuul_server/src/main/resources/application.yml
***
server: port: 18080 spring: application: name: spring-cloud-zuul-server cloud: nacos: discovery: server-addr: 192.168.44.129:8848 sentinel: transport: dashboard: localhost:8080 port: 8720 zuul: routes: consumer-route: path: /consumer/** serviceid: spring-cloud-consumer-fallback
代码清单:alibaba/sentinel-springcloud-high/zuul_server/src/main/java/com/springcloud/zuul_server/fallback/zuulfallbackprovider.java
***
public class zuulfallbackprovider implements zuulblockfallbackprovider { @override public string getroute() { return "*"; } @override public blockresponse fallbackresponse(string route, throwable cause) { recordlog.info(string.format("[sentinel defaultblockfallbackprovider] run fallback route: %s", route)); if (cause instanceof blockexception) { return new blockresponse(429, "sentinel block exception", route); } else { return new blockresponse(500, "system error", route); } } }
代码清单:alibaba/sentinel-springcloud-high/zuul_server/src/main/java/com/springcloud/zuul_server/config/zuulconfig.java
***
@configuration public class zuulconfig { @bean public zuulfilter sentinelzuulprefilter() { // we can also provider the filter order in the constructor. return new sentinelzuulprefilter(); } @bean public zuulfilter sentinelzuulpostfilter() { return new sentinelzuulpostfilter(); } @bean public zuulfilter sentinelzuulerrorfilter() { return new sentinelzuulerrorfilter(); } /** * 注册 zuulfallbackprovider */ @postconstruct public void doinit() { zuulblockfallbackmanager.registerprovider(new zuulfallbackprovider()); } }
最终,启动前需要配置jvm启动参数,增加-dcsp.sentinel.app.type=1
,来告诉sentinel控制台我们启动的服务是为 api gateway 类型。
顺次启动子工程provider_server、consumer_fallback、zuul_server,打开浏览器访问:http://www.lhsxpumps.com/_localhost:18080/consumer/hellobyfeign ,然后我们打开sentinel控制台,查看zuul_server服务,如图:
我们定制限流策略,依旧是qps为1,我们再次刷新http://www.lhsxpumps.com/_localhost:18080/consumer/hellobyfeign 页面,这时,页面上已经可以正产限流了,限流后显示的内容为:
{"code":429, "message":"sentinel block exception", "route":"consumer-route"}
这里注意,定义限流的是资源,千万不要定义错地方,限流定义如图:
从 1.6.0 版本开始,sentinel 提供了 spring cloud gateway 的适配模块,可以提供两种资源维度的限流:
工程依赖pom.xml如下:
代码清单:alibaba/sentinel-springcloud-high/gateway_server/pom.xml
***
<dependency> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-webflux</artifactid> </dependency> <dependency> <groupid>org.springframework.cloud</groupid> <artifactid>spring-cloud-starter-gateway</artifactid> </dependency> <dependency> <groupid>com.alibaba.csp</groupid> <artifactid>sentinel-spring-cloud-gateway-adapter</artifactid> </dependency>
代码清单:alibaba/sentinel-springcloud-high/gateway_server/src/main/resources/application.yml
***
server: port: 28080 spring: application: name: spring-cloud-gateway-server cloud: nacos: discovery: server-addr: 192.168.44.129:8848 sentinel: transport: dashboard: localhost:8080 port: 8720 gateway: enabled: true discovery: locator: lower-case-service-id: true routes: - id: consumer_server uri: lb://spring-cloud-consumer-fallback predicates: - method=get
同上一小节介绍的zuul,这里我们同样需要将两个sentinel有关spring cloud gateway的filter注入spring:sentinelgatewayfilter
和sentinelgatewayblockexceptionhandler
,这里因为在sentinel v1.6.0版本才加入spring cloud gateway的支持,很多地方还不是很完善,异常处理sentinelgatewayblockexceptionhandler
目前只能返回一个异常信息,在我们的系统中无法和上下游很好的结合,这里笔者自己重新实现了sentinelgatewayblockexceptionhandler
,并命名为jsonsentinelgatewayblockexceptionhandler
,返回参数定义成为json,这里不再注入sentinel提供的sentinelgatewayblockexceptionhandler
,而是改为笔者自己实现的jsonsentinelgatewayblockexceptionhandler
。
代码清单:alibaba/sentinel-springcloud-high/gateway_server/src/main/java/com/springcloud/gateway_server/config/gatewayconfig.java
***
@configuration public class gatewayconfig { private final list<viewresolver> viewresolvers; private final servercodecconfigurer servercodecconfigurer; public gatewayconfig(objectprovider<list<viewresolver>> viewresolversprovider, servercodecconfigurer servercodecconfigurer) { this.viewresolvers = viewresolversprovider.getifavailable(collections::emptylist); this.servercodecconfigurer = servercodecconfigurer; } @bean @order(ordered.highest_precedence) public jsonsentinelgatewayblockexceptionhandler jsonsentinelgatewayblockexceptionhandler() { // register the block exception handler for spring cloud gateway. return new jsonsentinelgatewayblockexceptionhandler(viewresolvers, servercodecconfigurer); } @bean @order(-1) public globalfilter sentinelgatewayfilter() { return new sentinelgatewayfilter(); } }
代码清单:alibaba/sentinel-springcloud-high/gateway_server/src/main/java/com/springcloud/gateway_server/exception/jsonsentinelgatewayblockexceptionhandler.java
***
public class jsonsentinelgatewayblockexceptionhandler implements webexceptionhandler { private list<viewresolver> viewresolvers; private list<httpmessagewriter<?>> messagewriters; public jsonsentinelgatewayblockexceptionhandler(list<viewresolver> viewresolvers, servercodecconfigurer servercodecconfigurer) { this.viewresolvers = viewresolvers; this.messagewriters = servercodecconfigurer.getwriters(); } private mono<void> writeresponse(serverresponse response, serverwebexchange exchange) { serverhttpresponse serverhttpresponse = exchange.getresponse(); serverhttpresponse.getheaders().add("content-type", "application/json;charset=utf-8"); byte[] datas = "{\"code\":403,\"msg\":\"sentinel block exception\"}".getbytes(standardcharsets.utf_8); databuffer buffer = serverhttpresponse.bufferfactory().wrap(datas); return serverhttpresponse.writewith(mono.just(buffer)); } @override public mono<void> handle(serverwebexchange exchange, throwable ex) { if (exchange.getresponse().iscommitted()) { return mono.error(ex); } // this exception handler only handles rejection by sentinel. if (!blockexception.isblockexception(ex)) { return mono.error(ex); } return handleblockedrequest(exchange, ex) .flatmap(response -> writeresponse(response, exchange)); } private mono<serverresponse> handleblockedrequest(serverwebexchange exchange, throwable throwable) { return gatewaycallbackmanager.getblockhandler().handlerequest(exchange, throwable); } private final supplier<serverresponse.context> contextsupplier = () -> new serverresponse.context() { @override public list<httpmessagewriter<?>> messagewriters() { return jsonsentinelgatewayblockexceptionhandler.this.messagewriters; } @override public list<viewresolver> viewresolvers() { return jsonsentinelgatewayblockexceptionhandler.this.viewresolvers; } }; }
笔者这里仅重写了writeresponse()
方法,讲返回信息简单的更改成了json格式,各位读者有需要可以根据自己的需求进行修改。
顺次启动provider_server、consumer_server和gateway_server,配置gateway_server jvm启动参数-dcsp.sentinel.app.type=1
,如图:
打开浏览器访问:http://localhost:28080/hellobyfeign ,刷新几次,页面正常返回hello, port is: 8000
,打开sentinel控制台,配置限流策略,qps限制为1,再刷新浏览器页面,这时,我们可以看到浏览器返回限流信息:
{"code":403,"msg":"sentinel block exception"}
测试成功。
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