Sentinelhttps://github.com/alibaba/Sentinel/wiki/%E4%BB%8B%E7%BB%8D中文官网
一句话解释,之前我们讲解过的Hystrix
下载地址https://github.com/alibaba/Sentinel/releases
作用:
服务使用中的各种问题:服务雪崩、服务降级、服务熔断、服务限流。
sentinel组件由2部分构成
安装步骤
下载到本地sentinel-dashboard-1.7.0.jar。前提条件8080端口不能被占用,java8环境OK,命令:java -jar sentinel-dashboard-1.7.0.jar
访问sentinel管理界面
http://localhost:8080 登录账号密码均为sentinel
http://localhost:8848/nacos/#/login
cloudalibaba-sentinel-service8401
com.alibaba.cloud
spring-cloud-starter-alibaba-nacos-discovery
com.alibaba.csp
sentinel-datasource-nacos
com.alibaba.cloud
spring-cloud-starter-alibaba-sentinel
org.springframework.cloud
spring-cloud-starter-openfeign
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-actuator
org.springframework.boot
spring-boot-devtools
runtime
true
cn.hutool
hutool-all
4.6.3
org.projectlombok
lombok
true
org.springframework.boot
spring-boot-starter-test
test
yml
server:
port: 8401
spring:
application:
name: cloudalibaba-sentinel-service
cloud:
nacos:
discovery:
#Nacos服务注册中心地址
server-addr: localhost:8848
sentinel:
transport:
#配置Sentinel dashboard地址
dashboard: localhost:8080
#默认8719端口,假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口
port: 8719
management:
endpoints:
web:
exposure:
include: '*'
主启动
@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{
public static void main(String[] args) {
SpringApplication.run(MainApp8401.class, args);
}
}
业务类FlowLimitController
@RestController
public class FlowLimitController
{
@GetMapping("/testA")
public String testA()
{
return "------testA";
}
@GetMapping("/testB")
public String testB()
{
return "------testB";
}
}
启动Sentinel8080 java -jar sentinel-dashboard-1.7.0.jar 启动微服务8401
启动8401微服务后查看sentienl控制台。空空如也,啥都没有因为Sentinel采用的懒加载说明,
执行一次访问即可http://localhost:8401/testA
直接->快速失败(系统默认)
配置及说明
表示1秒钟内查询1次就是OK,若超过次数1,就直接-快速失败,报默认错误
测试
快速点击访问http://localhost:8401/testA
结果
Blocked by Sentinel (flow limiting)
直接调用默认报错信息,技术方面OK,but,是否应该有我们自己的后续处理?类似有个fallback的兜底方法?
当关联的资源达到阈值时,就限流自己,当与A关联的资源B达到阀值后,就限流A自己,B惹事,A挂了
设置效果
当关联资源/testB的qps阀值超过1时,就限流/testA的Rest访问地址,当关联资源到阈值后限制配置好的资源名
访问testB成功
postman里新建多线程集合组
大批量线程高并发访问B,导致A失效了
多个请求调用了同一个微服务
链路流控模式指的是,当从某个接口过来的资源达到限流条件时,开启限流。它的功能有点类似于针对来源配置项,区别在于:针对来源是针对上级微服务,而链路流控是针对上级接口,也就是说它的粒度更细。
直接失败,抛出异常 Blocked by Sentinel (flow limiting)
公式:阈值除以coldFactor(默认值为3),经过预热时长后才会达到阈值
默认coldFactor为3,即请求 QPS 从 threshold / 3 开始,经预热时长逐渐升至设定的 QPS 阈值。
限流 冷启动
WarmUp配置
默认 coldFactor 为 3,即请求QPS从(threshold / 3) 开始,经多少预热时长才逐渐升至设定的 QPS 阈值。
案例,阀值为10+预热时长设置5秒。
系统初始化的阀值为10 / 3 约等于3,即阀值刚开始为3;然后过了5秒后阀值才慢慢升高恢复到10
多次点击http://localhost:8401/testB。刚开始不行,后续慢慢OK
应用场景
如:秒杀系统在开启的瞬间,会有很多流量上来,很有可能把系统打死,预热方式就是把为了保护系统,可慢慢的把流量放进来,慢慢的把阀值增长到设置的阀值
匀速排队,让请求以均匀的速度通过,阀值类型必须设成QPS,否则无效。
设置含义:/testA每秒1次请求,超过的话就排队等待,等待的超时时间为20000毫秒。
RT(平均响应时间,秒级)
平均响应时间 超出阈值 且 在时间窗口内通过的请求>=5,两个条件同时满足后触发降级
窗口期过后关闭断路器
RT最大4900(更大的需要通过-Dcsp.sentinel.statistic.max.rt=XXXX才能生效)
异常比列(秒级)
QPS >= 5 且异常比例(秒级统计)超过阈值时,触发降级;时间窗口结束后,关闭降级
异常数(分钟级)
异常数(分钟统计)超过阈值时,触发降级;时间窗口结束后,关闭降级
Sentinel 熔断降级会在调用链路中某个资源出现不稳定状态时(例如调用超时或异常比例升高),对这个资源的调用进行限制,让请求快速失败,避免影响到其它的资源而导致级联错误。
当资源被降级后,在接下来的降级时间窗口之内,对该资源的调用都自动熔断(默认行为是抛出 DegradeException)。
Sentinel的断路器是没有半开状态的
半开的状态系统自动去检测是否请求有异常,没有异常就关闭断路器恢复使用,有异常则继续打开断路器不可用。具体可以参考Hystrix
Hystrix断路器_不知名路人~的博客-CSDN博客
测试
@GetMapping("/testD")
public String testD()
{
//暂停几秒钟线程
try { TimeUnit.SECONDS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); }
log.info("testD 测试RT");
return "------testD";
}
测试
按照上述配置,
永远一秒钟打进来10个线程(大于5个了)调用testD,我们希望200毫秒处理完本次任务,
如果超过200毫秒还没处理完,在未来1秒钟的时间窗口内,断路器打开(保险丝跳闸)微服务不可用,保险丝跳闸断电了
后续我停止jmeter,没有这么大的访问量了,断路器关闭(保险丝恢复),微服务恢复OK
测试
@GetMapping("/testD")
public String testD()
{
log.info("testD 测试RT");
int age = 10/0;
return "------testD";
}
按照上述配置,
单独访问一次,必然来一次报错一次(int age = 10/0),调一次错一次;
开启jmeter后,直接高并发发送请求,多次调用达到我们的配置条件了。
断路器开启(保险丝跳闸),微服务不可用了,不再报错error而是服务降级了。
时间窗口一定要大于等于60秒。
异常数是按照分钟统计的
测试
@GetMapping("/testE")
public String testE()
{
log.info("testE 测试异常比例");
int age = 10/0;
return "------testE 测试异常比例";
}
http://localhost:8401/testE,第一次访问绝对报错,因为除数不能为零,
我们看到error窗口,但是达到5次报错后,进入熔断后降级。
何为热点
热点即经常访问的数据,很多时候我们希望统计或者限制某个热点数据中访问频次最高的TopN数据,并对其访问进行限流或者其它操作
兜底方法
分为系统默认和客户自定义,两种
之前的case,限流出问题后,都是用sentinel系统默认的提示:Blocked by Sentinel (flow limiting)
我们能不能自定?类似hystrix,某个方法出问题了,就找对应的兜底降级方法?
结论
从HystrixCommand 到@SentinelResource
代码
@GetMapping("/testHotKey")
@SentinelResource(value = "testHotKey",blockHandler = "dealHandler_testHotKey")
public String testHotKey(@RequestParam(value = "p1",required = false) String p1,
@RequestParam(value = "p2",required = false) String p2){
return "------testHotKey";
}
public String dealHandler_testHotKey(String p1,String p2,BlockException exception)
{
return "-----dealHandler_testHotKey";
}
sentinel系统默认的提示:Blocked by Sentinel (flow limiting)
配置
限流模式只支持QPS模式,固定写死了。(这才叫热点)
@SentinelResource注解的方法参数索引,0代表第一个参数,1代表第二个参数,以此类推
单机阀值以及统计窗口时长表示在此窗口时间超过阀值就限流。
上面的抓图就是第一个参数有值的话,1秒的QPS为1,超过就限流,限流后调用dealHandler_testHotKey支持方法。
1. @SentinelResource(value = "testHotKey") 异常打到了前台用户界面看到,不友好
2.@SentinelResource(value = "testHotKey",blockHandler = "dealHandler_testHotKey")
方法testHotKey里面第一个参数只要QPS超过每秒1次,马上降级处理,用了我们自己定义的
测试
http://localhost:8401/testHotKey?p1=abc 失败
http://localhost:8401/testHotKey?p1=abc&p2=33 失败
http://localhost:8401/testHotKey?p2=abc 成功
参数例外项
上述案例演示了第一个参数p1,当QPS超过1秒1次点击后马上被限流
特例情况 普通 超过1秒钟一个后,达到阈值1后马上被限流。我们期望p1参数当它是某个特殊值时,它的限流值和平时不一样。假如当p1的值等于5时,它的阈值可以达到200
配置
测试
http://localhost:8401/testHotKey?p1=5 √
http://localhost:8401/testHotKey?p1=3 ×
当p1等于5的时候,阈值变为200 当p1不等于5的时候,阈值就是平常的1
热点参数的注意点,参数必须是基本类型或者String
@SentinelResource
处理的是Sentinel控制台配置的违规情况,有blockHandler方法配置的兜底处理;
RuntimeException
int age = 10/0,这个是java运行时报出的运行时异常RunTimeException,@SentinelResource不管。
总结
@SentinelResource主管配置出错,运行出错该走异常走异常
启动Nacos成功 http://localhost:8848/nacos/#/login
启动Sentinel成功 java -jar sentinel-dashboard-1.7.0.jar
cloudalibaba-sentinel-service8401
pom
com.alibaba.cloud
spring-cloud-starter-alibaba-nacos-discovery
com.zjh.springcloud
cloud-api-commons
${project.version}
com.alibaba.csp
sentinel-datasource-nacos
com.alibaba.cloud
spring-cloud-starter-alibaba-sentinel
org.springframework.cloud
spring-cloud-starter-openfeign
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-actuator
org.springframework.boot
spring-boot-devtools
runtime
true
cn.hutool
hutool-all
4.6.3
org.projectlombok
lombok
true
org.springframework.boot
spring-boot-starter-test
test
yml
server:
port: 8401
spring:
application:
name: cloudalibaba-sentinel-service
cloud:
nacos:
discovery:
server-addr: localhost:8848 #Nacos服务注册中心地址
sentinel:
transport:
dashboard: localhost:8080 #配置Sentinel dashboard地址
port: 8719
management:
endpoints:
web:
exposure:
include: '*'
业务类RateLimitController
@RestController
public class RateLimitController
{
@GetMapping("/byResource")
@SentinelResource(value = "byResource",blockHandler = "handleException")
public CommonResult byResource()
{
return new CommonResult(200,"按资源名称限流测试OK",new Payment(2020L,"serial001"));
}
public CommonResult handleException(BlockException exception)
{
return new CommonResult(444,exception.getClass().getCanonicalName()+"\t 服务不可用");
}
}
主启动
@EnableDiscoveryClient
@SpringBootApplication
public class MainApp8401
{
public static void main(String[] args) {
SpringApplication.run(MainApp8401.class, args);
}
}
配置流控规则
步骤
图形配置和代码关系
表示1秒钟内查询次数大于1,就跑到我们自定义的处流,限流
测试:1秒钟点击1下,OK;超过上述,疯狂点击,返回了自己定义的限流处理信息,限流发生
额外问题
Sentinel控制台,流控规则消失了?????
通过访问的URL来限流,会返回Sentinel自带默认的限流处理信息
业务类
@RestController
public class RateLimitController
{
@GetMapping("/byResource")
@SentinelResource(value = "byResource",blockHandler = "handleException")
public CommonResult byResource()
{
return new CommonResult(200,"按资源名称限流测试OK",new Payment(2020L,"serial001"));
}
public CommonResult handleException(BlockException exception)
{
return new CommonResult(444,exception.getClass().getCanonicalName()+"\t 服务不可用");
}
@GetMapping("/rateLimit/byUrl")
@SentinelResource(value = "byUrl")
public CommonResult byUrl()
{
return new CommonResult(200,"按url限流测试OK",new Payment(2020L,"serial002"));
}
}
访问一次
http://localhost:8401/rateLimit/byUrl
Sentinel控制台配置
1 系统默认的,没有体现我们自己的业务要求。
2 依照现有条件,我们自定义的处理方法又和业务代码耦合在一块,不直观。
3 每个业务方法都添加一个兜底的,那代码膨胀加剧。
4 全局统一的处理方法没有体现。
创建CustomerBlockHandler类用于自定义限流处理逻辑
CustomerBlockHandler
public class CustomerBlockHandler
{
public static CommonResult handleException(BlockException exception){
return new CommonResult(2020,"自定义的限流处理信息......CustomerBlockHandler");
}
}
RateLimitController
@RestController
public class RateLimitController
{
@GetMapping("/byResource")
@SentinelResource(value = "byResource",blockHandler = "handleException")
public CommonResult byResource()
{
return new CommonResult(200,"按资源名称限流测试OK",new Payment(2020L,"serial001"));
}
public CommonResult handleException(BlockException exception)
{
return new CommonResult(444,exception.getClass().getCanonicalName()+"\t 服务不可用");
}
@GetMapping("/rateLimit/byUrl")
@SentinelResource(value = "byUrl")
public CommonResult byUrl()
{
return new CommonResult(200,"按url限流测试OK",new Payment(2020L,"serial002"));
}
/**
* 自定义通用的限流处理逻辑,
blockHandlerClass = CustomerBlockHandler.class
blockHandler = handleException2
上述配置:找CustomerBlockHandler类里的handleException2方法进行兜底处理
*/
/**
* 自定义通用的限流处理逻辑
*/
@GetMapping("/rateLimit/customerBlockHandler")
@SentinelResource(value = "customerBlockHandler",
blockHandlerClass = CustomerBlockHandler.class, blockHandler = "handleException2")
public CommonResult customerBlockHandler()
{
return new CommonResult(200,"按客户自定义限流处理逻辑");
}
}
启动微服务后先调用一次http://localhost:8401/rateLimit/customerBlockHandler
Sentinel控制台配置
所有的代码都要用try-catch-finally方式进行处理,o(╥﹏╥)o
Sentinel主要有三个核心Api
SphU定义资源 Tracer定义统计 ContextUtil定义了上下文
sentinel整合ribbon+openFeign+fallback
启动nacos和sentinel
提供者9003/9004
新建cloudalibaba-provider-payment9003/9004两个一样的做法
com.alibaba.cloud
spring-cloud-starter-alibaba-nacos-discovery
com.zjh.springcloud
cloud-api-commons
${project.version}
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-actuator
org.springframework.boot
spring-boot-devtools
runtime
true
org.projectlombok
lombok
true
org.springframework.boot
spring-boot-starter-test
test
yml
server:
port: 9003
spring:
application:
name: nacos-payment-provider
cloud:
nacos:
discovery:
server-addr: localhost:8848 #配置Nacos地址
management:
endpoints:
web:
exposure:
include: '*'
主启动
@SpringBootApplication
@EnableDiscoveryClient
public class PaymentMain9003
{
public static void main(String[] args) {
SpringApplication.run(PaymentMain9003.class, args);
}
}
业务类
@RestController
public class PaymentController
{
@Value("${server.port}")
private String serverPort;
public static HashMap hashMap = new HashMap<>();
static
{
hashMap.put(1L,new Payment(1L,"28a8c1e3bc2742d8848569891fb42181"));
hashMap.put(2L,new Payment(2L,"bba8c1e3bc2742d8848569891ac32182"));
hashMap.put(3L,new Payment(3L,"6ua8c1e3bc2742d8848569891xt92183"));
}
@GetMapping(value = "/paymentSQL/{id}")
public CommonResult paymentSQL(@PathVariable("id") Long id)
{
Payment payment = hashMap.get(id);
CommonResult result = new CommonResult(200,"from mysql,serverPort: "+serverPort,payment);
return result;
}
}
测试地址:http://localhost:9003/paymentSQL/1
消费者84
新建cloudalibaba-consumer-nacos-order84
com.alibaba.cloud
spring-cloud-starter-alibaba-nacos-discovery
com.alibaba.cloud
spring-cloud-starter-alibaba-sentinel
com.zjh.springcloud
cloud-api-commons
${project.version}
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-actuator
org.springframework.boot
spring-boot-devtools
runtime
true
org.projectlombok
lombok
true
org.springframework.boot
spring-boot-starter-test
test
yml
server:
port: 84
spring:
application:
name: nacos-order-consumer
cloud:
nacos:
discovery:
server-addr: localhost:8848
sentinel:
transport:
#配置Sentinel dashboard地址
dashboard: localhost:8080
#默认8719端口,假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口
port: 8719
#消费者将要去访问的微服务名称(注册成功进nacos的微服务提供者)
service-url:
nacos-user-service: http://nacos-payment-provider
主启动
@EnableDiscoveryClient
@SpringBootApplication
public class OrderNacosMain84
{
public static void main(String[] args) {
SpringApplication.run(OrderNacosMain84.class, args);
}
}
业务类
ApplicationContextConfig
@Configuration
public class ApplicationContextConfig
{
@Bean
@LoadBalanced
public RestTemplate getRestTemplate()
{
return new RestTemplate();
}
}
CircleBreakerController
fallback管运行异常,blockHandler管配置违规
@RestController
@Slf4j
public class CircleBreakerController
{
public static final String SERVICE_URL = "http://nacos-payment-provider";
@Resource
private RestTemplate restTemplate;
@RequestMapping("/consumer/fallback/{id}")
@SentinelResource(value = "fallback")
public CommonResult fallback(@PathVariable Long id)
{
CommonResult result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id);
if (id == 4) {
throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常....");
}else if (result.getData() == null) {
throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常");
}
return result;
}
}
测试地址:http://localhost:84/consumer/fallback/1
没有任何配置给客户error页面,不友好
只配置fallback
@RestController
@Slf4j
public class CircleBreakerController
{
public static final String SERVICE_URL = "http://nacos-payment-provider";
@Resource
private RestTemplate restTemplate;
@RequestMapping("/consumer/fallback/{id}")
@SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback负责业务异常
public CommonResult fallback(@PathVariable Long id)
{
CommonResult result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id);
if (id == 4) {
throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常....");
}else if (result.getData() == null) {
throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常");
}
return result;
}
public CommonResult handlerFallback(@PathVariable Long id,Throwable e) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(444,"兜底异常handlerFallback,exception内容 "+e.getMessage(),payment);
}
}
结果
只配置blockHandler
@RestController
@Slf4j
public class CircleBreakerController
{
public static final String SERVICE_URL = "http://nacos-payment-provider";
@Resource
private RestTemplate restTemplate;
@RequestMapping("/consumer/fallback/{id}")
@SentinelResource(value = "fallback",blockHandler = "blockHandler") //blockHandler负责在sentinel里面配置的降级限流
public CommonResult fallback(@PathVariable Long id)
{
CommonResult result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id);
if (id == 4) {
throw new IllegalArgumentException ("非法参数异常....");
}else if (result.getData() == null) {
throw new NullPointerException ("NullPointerException,该ID没有对应记录");
}
return result;
}
public CommonResult handlerFallback(@PathVariable Long id,Throwable e) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(444,"fallback,无此流水,exception "+e.getMessage(),payment);
}
public CommonResult blockHandler(@PathVariable Long id,BlockException blockException) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException "+blockException.getMessage(),payment);
}
}
异常超过2次后,断路器打开,断电跳闸,系统被保护
fallback和blockHandler都配置
@RestController
@Slf4j
public class CircleBreakerController
{
public static final String SERVICE_URL = "http://nacos-payment-provider";
@Resource
private RestTemplate restTemplate;
@RequestMapping("/consumer/fallback/{id}")
@SentinelResource(value = "fallback",fallback = "handlerFallback",blockHandler = "blockHandler")
public CommonResult fallback(@PathVariable Long id)
{
CommonResult result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id);
if (id == 4) {
throw new IllegalArgumentException ("非法参数异常....");
}else if (result.getData() == null) {
throw new NullPointerException ("NullPointerException,该ID没有对应记录");
}
return result;
}
public CommonResult handlerFallback(@PathVariable Long id,Throwable e) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(444,"fallback,无此流水,exception "+e.getMessage(),payment);
}
public CommonResult blockHandler(@PathVariable Long id,BlockException blockException) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException "+blockException.getMessage(),payment);
}
}
若 blockHandler 和 fallback 都进行了配置,则被限流降级而抛出 BlockException 时只会进入 blockHandler 处理逻辑。
忽略属性.......
@RestController
@Slf4j
public class CircleBreakerController
{
public static final String SERVICE_URL = "http://nacos-payment-provider";
@Resource
private RestTemplate restTemplate;
@RequestMapping("/consumer/fallback/{id}")
@SentinelResource(value = "fallback", fallback = "handlerFallback", blockHandler = "blockHandler",
exceptionsToIgnore = {IllegalArgumentException.class})
public CommonResult fallback(@PathVariable Long id)
{
CommonResult result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id);
if (id == 4) {
throw new IllegalArgumentException ("非法参数异常....");
}else if (result.getData() == null) {
throw new NullPointerException ("NullPointerException,该ID没有对应记录");
}
return result;
}
public CommonResult handlerFallback(@PathVariable Long id,Throwable e) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(444,"fallback,无此流水,exception "+e.getMessage(),payment);
}
public CommonResult blockHandler(@PathVariable Long id,BlockException blockException) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException "+blockException.getMessage(),payment);
}
}
修改84模块,84消费者调用提供者9003,Feign组件一般是消费侧
com.alibaba.cloud
spring-cloud-starter-alibaba-nacos-discovery
com.alibaba.cloud
spring-cloud-starter-alibaba-sentinel
org.springframework.cloud
spring-cloud-starter-openfeign
com.zjh.springcloud
cloud-api-commons
${project.version}
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-actuator
org.springframework.boot
spring-boot-devtools
runtime
true
org.projectlombok
lombok
true
org.springframework.boot
spring-boot-starter-test
test
yml 激活Sentinel对Feign的支持
server:
port: 84
spring:
application:
name: nacos-order-consumer
cloud:
nacos:
discovery:
#Nacos服务注册中心地址
server-addr: localhost:8848
sentinel:
transport:
#配置Sentinel dashboard地址
dashboard: localhost:8080
#默认8719端口,假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口
port: 8719management:
endpoints:
web:
exposure:
include: '*'
# 激活Sentinel对Feign的支持
feign:
sentinel:
enabled: true
主启动 添加@EnableFeignClients启动Feign的功能
@EnableDiscoveryClient
@SpringBootApplication
@EnableFeignClients
public class OrderNacosMain84
{
public static void main(String[] args) {
SpringApplication.run(OrderNacosMain84.class, args);
}
}
业务类
带@FeignClient注解的业务接口
/** 使用 fallback 方式是无法获取异常信息的,
* 如果想要获取异常信息,可以使用 fallbackFactory参数
*/
@FeignClient(value = "nacos-payment-provider",fallback = PaymentFallbackService.class)//调用中关闭9003服务提供者
public interface PaymentService
{
@GetMapping(value = "/paymentSQL/{id}")
public CommonResult paymentSQL(@PathVariable("id") Long id);
}
fallback = PaymentFallbackService.class
@Component
public class PaymentFallbackService implements PaymentService
{
@Override
public CommonResult paymentSQL(Long id)
{
return new CommonResult<>(444,"服务降级返回,没有该流水信息",new Payment(id, "errorSerial......"));
}
}
Controller
@RestController
@Slf4j
public class CircleBreakerController
{
public static final String SERVICE_URL = "http://nacos-payment-provider";
@Resource
private RestTemplate restTemplate;
@RequestMapping("/consumer/fallback/{id}")
//@SentinelResource(value = "fallback") //没有配置
//@SentinelResource(value = "fallback",fallback = "handlerFallback") //fallback只负责业务异常
//@SentinelResource(value = "fallback",blockHandler = "blockHandler") //blockHandler只负责sentinel控制台配置违规
@SentinelResource(value = "fallback",fallback = "handlerFallback",blockHandler = "blockHandler",
exceptionsToIgnore = {IllegalArgumentException.class})
public CommonResult fallback(@PathVariable Long id)
{
CommonResult result = restTemplate.getForObject(SERVICE_URL + "/paymentSQL/"+id,CommonResult.class,id);
if (id == 4) {
throw new IllegalArgumentException ("IllegalArgumentException,非法参数异常....");
}else if (result.getData() == null) {
throw new NullPointerException ("NullPointerException,该ID没有对应记录,空指针异常");
}
return result;
}
//本例是fallback
public CommonResult handlerFallback(@PathVariable Long id,Throwable e) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(444,"兜底异常handlerFallback,exception内容 "+e.getMessage(),payment);
}
//本例是blockHandler
public CommonResult blockHandler(@PathVariable Long id,BlockException blockException) {
Payment payment = new Payment(id,"null");
return new CommonResult<>(445,"blockHandler-sentinel限流,无此流水: blockException "+blockException.getMessage(),payment);
}
//==================OpenFeign
@Resource
private PaymentService paymentService;
@GetMapping(value = "/consumer/openfeign/{id}")
public CommonResult paymentSQL(@PathVariable("id") Long id)
{
if(id == 4)
{
throw new RuntimeException("没有该id");
}
return paymentService.paymentSQL(id);
}
}
http://localhost:84/consumer/paymentSQL/1
测试84调用9003,此时故意关闭9003微服务提供者,看84消费侧自动降级,不会被耗死
一旦我们重启应用,sentinel规则将消失,生产环境需要将配置规则进行持久化。
将限流配置规则持久化进Nacos保存,只要刷新8401某个rest地址,sentinel控制台
的流控规则就能看到,只要Nacos里面的配置不删除,针对8401上sentinel上的流控规则持续有效
步骤
修改cloudalibaba-sentinel-service8401
com.alibaba.csp
sentinel-datasource-nacos
yml
server:
port: 8401spring:
application:
name: cloudalibaba-sentinel-service
cloud:
nacos:
discovery:
server-addr: localhost:8848 #Nacos服务注册中心地址
sentinel:
transport:
dashboard: localhost:8080 #配置Sentinel dashboard地址
port: 8719
datasource:
ds1:
nacos:
server-addr: localhost:8848
dataId: cloudalibaba-sentinel-service #${spring.application.name}
groupId: DEFAULT_GROUP
data-type: json
rule-type: flowmanagement:
endpoints:
web:
exposure:
include: '*'feign:
sentinel:
enabled: true # 激活Sentinel对Feign的支持
添加Nacos业务规则配置
内容解析
[
{
"resource": "/rateLimit/byUrl",
"limitApp": "default",
"grade": 1,
"count": 1,
"strategy": 0,
"controlBehavior": 0,
"clusterMode": false
}
]
resource:资源名称;
limitApp:来源应用;
grade:阈值类型,0表示线程数,1表示QPS;
count:单机阈值;
strategy:流控模式,0表示直接,1表示关联,2表示链路;
controlBehavior:流控效果,0表示快速失败,1表示Warm Up,2表示排队等待;
clusterMode:是否集群。
启动8401后刷新sentinel发现业务规则有了
停止8401再看sentinel
调用:http://localhost:8401/rateLimit/byUrl 重新配置出现了,持久化验证通过