Sentinel 介绍与安装

Sentinel是阿里巴巴开发的分布式系统的流量防卫兵

一、Sentinel 是什么？

随着微服务的流行，服务和服务之间的稳定性变得越来越重要。Sentinel 以流量为切入点，从流量控制、熔断降级、系统负载保护等多个维度保护服务的稳定性。

As distributed systems become increasingly popular, the reliability between services is becoming more important than ever before. Sentinel takes "flow" as breakthrough point, and works on multiple fields including flow control, traffic shaping, circuit breaking and system adaptive protection, to guarantee reliability and resilience for microservices.

Sentinel has the following features:

• Rich applicable scenarios: Sentinel has been wildly used in Alibaba, and has covered almost all the core-scenarios in Double-11 (11.11) Shopping Festivals in the past 10 years, such as “Second Kill” which needs to limit burst flow traffic to meet the system capacity, message peak clipping and valley fills, circuit breaking for unreliable downstream services, cluster flow control, etc.
• Real-time monitoring: Sentinel also provides real-time monitoring ability. You can see the runtime information of a single machine in real-time, and the aggregated runtime info of a cluster with less than 500 nodes.
• Widespread open-source ecosystem: Sentinel provides out-of-box integrations with commonly-used frameworks and libraries such as Spring Cloud, Dubbo and gRPC. You can easily use Sentinel by simply add the adapter dependency to your services.
• Polyglot support: Sentinel has provided native support for Java, Go and C++.
• Various SPI extensions: Sentinel provides easy-to-use SPI extension interfaces that allow you to quickly customize your logic, for example, custom rule management, adapting data sources, and so on.

Sentinel 具有以下特征:

• 丰富的应用场景：Sentinel 承接了阿里巴巴近 大促流量的核心场景，例如秒杀（即突发流量控制在系统容量可以承受的范围）、消息削峰填谷、集群流量控制、实时熔断下游不可用应用等。
• 完备的实时监控：Sentinel 同时提供实时的监控功能。您可以在控制台中看到接入应用的单台机器秒级数据，甚至 500 台以下规模的集群的汇总运行情况。
• 广泛的开源生态：Sentinel 提供开箱即用的与其它开源框架/库的整合模块，例如与 Spring Cloud、Apache Dubbo、gRPC、Quarkus 的整合。您只需要引入相应的依赖并进行简单的配置即可快速地接入 Sentinel。同时 Sentinel 提供 Java/Go/C++ 等多语言的原生实现。
• 完善的 SPI 扩展机制：Sentinel 提供简单易用、完善的 SPI 扩展接口。您可以通过实现扩展接口来快速地定制逻辑。例如定制规则管理、适配动态数据源等。

Sentinel 分为两个部分:

• 核心库（Java 客户端）不依赖任何框架/库，能够运行于所有 Java 运行时环境，同时对 Dubbo / Spring Cloud 等框架也有较好的支持。
• 控制台（Dashboard）基于 Spring Boot 开发，打包后可以直接运行，不需要额外的 Tomcat 等容器。

二、安装sentinel控制台
首先从下载地址: https://github.com/alibaba/Sentinel/releases下载相关的jar

启动jar包：java -jar sentinel-dashboard-1.8.3.jar

访问 localhost:8080 默认账号密码都是：sentinel

三、验证sentinel安装环境

1、登录界面，输入sentinel / sentinel

2、然后进入 主页面，表示sentinel安装成功