Sentinel网关限流

背景

在微服务架构下，每个服务的性能都不同，为避免出现流量洪峰将服务冲垮，需要依赖限流工具来保护服务的稳定性。sentinel是阿里提供的限流工具，社区活跃，功能也很全面，包含实时监控、流控、熔断等功能。它也提供了spring-cloud-gateway的支持，可以很方便和spring-gateway进行整合。

目标

spring-gateway服务添加sentinel支持，并通过sentinel dashboard进行规则配置，规则数据存在nacos里，支持规则变更实时生效。

方案

服务结构

spring-gateway改动

引入工程依赖

在pom文件里添加sentinel的依赖：

|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| <!--sentinel支持spring--> <dependency> ``<groupId>com.alibaba.cloud</groupId> ``<artifactId>spring-cloud-starter-alibaba-sentinel</artifactId> </dependency> <!--自动集成spring gateway--> <dependency> ``<groupId>com.alibaba.cloud</groupId> ``<artifactId>spring-cloud-alibaba-sentinel-gateway</artifactId> </dependency> <!--支持nacos的动态数据源--> <dependency> ``<groupId>com.alibaba.csp</groupId> ``<artifactId>sentinel-datasource-nacos</artifactId> </dependency> |

加载限流规则

在application.properties文件里添加sentinel规则对应nacos配置信息：

|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| project.name=spring-gateway sentinel.nacos.``default``.namespace=SENTINEL_GROUP spring.cloud.sentinel.datasource.gw_api_group.nacos.server-addr=${spring.cloud.nacos.config.server-addr} spring.cloud.sentinel.datasource.gw_api_group.nacos.namespace=${spring.cloud.nacos.config.namespace} spring.cloud.sentinel.datasource.gw_api_group.nacos.data-id=${project.name}-gw_api_group-rules spring.cloud.sentinel.datasource.gw_api_group.nacos.group-id=${sentinel.nacos.``default``.namespace} spring.cloud.sentinel.datasource.gw_api_group.nacos.data-type=json spring.cloud.sentinel.datasource.gw_api_group.nacos.rule-type=gw_api_group spring.cloud.sentinel.datasource.gw_flow.nacos.server-addr=${spring.cloud.nacos.config.server-addr} spring.cloud.sentinel.datasource.gw_flow.nacos.namespace=${spring.cloud.nacos.config.namespace} spring.cloud.sentinel.datasource.gw_flow.nacos.data-id=${project.name}-gw_flow-rules spring.cloud.sentinel.datasource.gw_flow.nacos.group-id=${sentinel.nacos.``default``.namespace} spring.cloud.sentinel.datasource.gw_flow.nacos.data-type=json spring.cloud.sentinel.datasource.gw_flow.nacos.rule-type=gw_flow spring.cloud.sentinel.datasource.degrade.nacos.server-addr=${spring.cloud.nacos.config.server-addr} spring.cloud.sentinel.datasource.degrade.nacos.namespace=${spring.cloud.nacos.config.namespace} spring.cloud.sentinel.datasource.degrade.nacos.data-id=${project.name}-degrade-rules spring.cloud.sentinel.datasource.degrade.nacos.group-id=${sentinel.nacos.``default``.namespace} spring.cloud.sentinel.datasource.degrade.nacos.data-type=json spring.cloud.sentinel.datasource.degrade.nacos.rule-type=degrade spring.cloud.sentinel.datasource.system.nacos.server-addr=${spring.cloud.nacos.config.server-addr} spring.cloud.sentinel.datasource.system.nacos.namespace=${spring.cloud.nacos.config.namespace} spring.cloud.sentinel.datasource.system.nacos.data-id=${project.name}-system-rules spring.cloud.sentinel.datasource.system.nacos.group-id=${sentinel.nacos.``default``.namespace} spring.cloud.sentinel.datasource.system.nacos.data-type=json spring.cloud.sentinel.datasource.system.nacos.rule-type=system spring.cloud.sentinel.datasource.authority.nacos.server-addr=${spring.cloud.nacos.config.server-addr} spring.cloud.sentinel.datasource.authority.nacos.namespace=${spring.cloud.nacos.config.namespace} spring.cloud.sentinel.datasource.authority.nacos.data-id=${project.name}-authority-rules spring.cloud.sentinel.datasource.authority.nacos.group-id=${sentinel.nacos.``default``.namespace} spring.cloud.sentinel.datasource.authority.nacos.data-type=json spring.cloud.sentinel.datasource.authority.nacos.rule-type=authority spring.cloud.sentinel.datasource.param_flow.nacos.server-addr=${spring.cloud.nacos.config.server-addr} spring.cloud.sentinel.datasource.param_flow.nacos.namespace=${spring.cloud.nacos.config.namespace} spring.cloud.sentinel.datasource.param_flow.nacos.data-id=${project.name}-param_flow-rules spring.cloud.sentinel.datasource.param_flow.nacos.group-id=${sentinel.nacos.``default``.namespace} spring.cloud.sentinel.datasource.param_flow.nacos.data-type=json spring.cloud.sentinel.datasource.param_flow.nacos.rule-type=param_flow |

限流处理

请求击中限流规则后，我们要对限流异常进行处理。可以通过自定义BlockRequestHandler来定制处理逻辑，也可以使用sentinel spring gateway的默认处理器，支持需要在配置文件里加上一下信息：

|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| # mode=response代表正常返回响应，mode=redirect代表重定向某个页面 spring.cloud.sentinel.scg.fallback.mode=response spring.cloud.sentinel.scg.fallback.response-body={``"success"``: ``false``, ``"message"``:``"too many requests(flow limiting)"``, ``"code"``: ``429``} spring.cloud.sentinel.scg.fallback.response-status=429 |

sentinel dashboard部署

sentinel dashboard是sentinel的管理后台代码，做了定制支持nacos，代码在仓库：GitHub - xsg22/Sentinel at sentinel-nacos-1.8

通过maven打出jar包后，支持传到服务器上进行部署。也可以使用已有的jar：https://download.csdn.net/download/xsgnzb/88522419

部署完整命令如下：

|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| java -jar sentinel-dashboard.jar --auth.enabled=``true --auth.username=admin --auth.password=123456 --server.port=9090 --spring.cloud.nacos.config.namespace=xxx --spring.cloud.nacos.config.server-addr=xxx |

部署的时候要注意几个参数：

|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| # 访问端口 server.port=``9090 # 登录账号 auth.enabled=``true auth.username=admin auth.password=``123456 # nacos连接地址 spring.cloud.nacos.config.server-addr=xxx spring.cloud.nacos.config.namespace=xxx |

数据源

sentinel包含7种规则类型，这些规则数据存放在nacos里。配置格式是，dataId={[project.name](http://project.name/ "project.name")}-{ruleType}-rules，group=SENTINEL_GROUP。例如，限流规则对应的dataId=spring-gateway-gw_flow-rules。

这是sentinel定义的RuleType：

|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| public enum RuleType { ``/** ``* 限流规则，非网关模式 ``*/ ``FLOW(``"flow"``, FlowRule.``class``), ``/** ``* 降级规则 ``*/ ``DEGRADE(``"degrade"``, DegradeRule.``class``), ``/** ``* 根据请求参数进行限流的规则 ``*/ ``PARAM_FLOW(``"param-flow"``, ParamFlowRule.``class``), ``/** ``* 系统规则，根据cpu使用率、load指标进行限流 ``*/ ``SYSTEM(``"system"``, SystemRule.``class``), ``/** ``* 授权规则，app的白名单/黑名单 ``*/ ``AUTHORITY(``"authority"``, AuthorityRule.``class``), ``/** ``* 限流规则，网关模式 ``*/ ``GW_FLOW(``"gw-flow"``, ``"com.alibaba.csp.sentinel.adapter.gateway.common.rule.GatewayFlowRule"``), ``/** ``* api定义信息 ``*/ ``GW_API_GROUP(``"gw-api-group"``, ``"com.alibaba.csp.sentinel.adapter.gateway.common.api.ApiDefinition"``); } |

注意，使用网关模式对接时，限流规则不能放到flow类型下，要使用gw_flow类型。