熔断、限流和降级：Sentinel

集成&开发

环境和脚本

sentinel官方示例

sentinel中文文档

sentinel与gin整合

sentinel与grpc整合

go get -u github.com/alibaba/sentinel-golang

1. 新增Sentinel中间件

package middleware

import (
	sentinel "github.com/alibaba/sentinel-golang/api"
	"github.com/alibaba/sentinel-golang/core/flow"
	"github.com/gin-gonic/gin"
	"go.uber.org/zap"
)

// Sentinel 中间件
func Sentinel() gin.HandlerFunc {
	return func(ctx *gin.Context) {
		err := sentinel.InitDefault()
		if err != nil {
			zap.S().Infof("Sentinel初始化失败：%v", err.Error())
		}
		_, err = flow.LoadRules([]*flow.Rule{
			{
				Resource:               ctx.Request.Method + ":" + ctx.FullPath(),
				TokenCalculateStrategy: flow.Direct,
				ControlBehavior:        flow.Reject,
				Threshold:              1,
				StatIntervalInMs:       2000,
			},
		})
		if err != nil {
			zap.S().Infof("Sentinel规则加载失败：%v", err.Error())
		}
		ctx.Next()
	}
}

2. 修改路由初始化代码

import (
	sentinelPlugin "github.com/sentinel-group/sentinel-go-adapters/gin"
	......
)

// 处理跨域请求
roots.Use(middleware.Cors())

roots.
	// 调用Sentinel中间件
	Use(middleware.Sentinel()).
	// 在gin中集成Sentinel插件，Resource采用sentinelPlugin的方式
	// Resource = ctx.Request.Method + ":" + ctx.FullPath()
	Use(sentinelPlugin.SentinelMiddleware(
		sentinelPlugin.WithBlockFallback(func(ctx *gin.Context) {
			ctx.AbortWithStatusJSON(http.StatusTooManyRequests, gin.H{
				"code": http.StatusTooManyRequests,
				"msg":  "请求过于频繁，请稍后重试",
				"data": gin.H{},
			})
		})),
	)

......

可以看到，通过插件整合的方式，就不需要再在每个接口中都调用下面这样的代码。

e, b := sentinel.Entry("some-test", sentinel.WithTrafficType(base.Inbound))
if b != nil {
	// Blocked. We could get the block reason from the BlockError.
	time.Sleep(time.Duration(rand.Uint64()%10) * time.Millisecond)
} else {
	// Passed, wrap the logic here.
	time.Sleep(time.Duration(rand.Uint64()%10) * time.Millisecond)
	// Be sure the entry is exited finally.
	e.Exit()
}

代码的侵入性几乎为零。

3. 与GRPC的整合（略）

文档写的比较清楚，按照文档来很容易实现。

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