alibaba限流組件Sentinel實戰

序

本文主要研究一下如何使用alibaba開源的限流組件Sentinel

maven

<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-sentinel</artifactId>
			<version>0.2.0.BUILD-SNAPSHOT</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
		</dependency>
		<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>

• spring-cloud-starter-sentinel在maven倉庫沒有的話本身本地install一下

配置

server.port=8080
spring.application.name=sentinel-demo
spring.cloud.sentinel.port=7080
spring.cloud.sentinel.dashboard=localhost:9999
management.endpoints.web.exposure.include=*

• 這裏指定應用的端口爲8080，與sentinel server通訊端口爲7080，sentinel server的地址爲localhost:9999

啓動dashboard

java -Dserver.port=9999 \
-Dcsp.sentinel.dashboard.server=localhost:9999 \
-Dproject.name=sentinel-dashboard \
-jar sentinel-dashboard.jar

增長限流規則

訪問應用的sentinel端點：http://localhost:8080/actuator/sentinel，返回以下：

{
  "DegradeRules": [],
  "SystemRules": [],
  "FlowRules": [
    {
      "resource": "/actuator",
      "limitApp": "default",
      "grade": 1,
      "count": 10,
      "strategy": 0,
      "refResource": null,
      "controlBehavior": 0,
      "warmUpPeriodSec": 10,
      "maxQueueingTimeMs": 500
    }
  ],
  "properties": {
    "enabled": true,
    "port": "7080",
    "dashboard": "localhost:9999",
    "filter": {
      "order": -2147483648,
      "urlPatterns": [
        "/*"
      ]
    }
  }
}

限流驗證

wrk -t12 -c1000 -d10s -T30s  --latency http://localhost:8080/actuator

訪問dashboard

能夠看到每分鐘的拒絕次數，另外也能夠經過實時監控來看圖形化曲線

藍色的曲線爲b_qps，即被blocked的請求的qps

被流控以後，接口返回

curl -i http://localhost:8080/actuator
HTTP/1.1 200
Transfer-Encoding: chunked
Date: Sun, 12 Aug 2018 13:41:15 GMT

Blocked by Sentinel (flow limiting)

小結

這裏使用的是spring-cloud-alibaba的組件，跟spring-cloud-netlfix相似，是alibaba的開源組件融入spring cloud的部分，如今提供了對sentinel的集成，很是方便。

doc

• sentinel-example
• sentinel-dashboard
• Sentinel: 分佈式系統的流量防衛兵