跟我学Spring Cloud（Finchley版）-03-监控：强大的Boot Actuator

第2节（ 跟我学Spring Cloud（Finchley版）-02-构建分布式应用 ）说过：

应用没有监控，没有画板，一切指标都没有。在这个Growth Hack逐渐成为主流的时代，不弄个Dashboard把系统压力、QPS、CPU、内存、日活啥的可视化，你好意思出来混吗……

本节我们来解决该问题。

Spring Boot Actuator是Spring Boot官方提供的监控组件。只需为项目添加以下依赖，即可就整合Spring Boot Actuator。

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

监控端点

Actuator为我们提供了很多监控端点，如下表所示。

表-Spring Boot Actuator常用端点及描述

只需访问http://{ip}:{port}/actuator/{endpoint} 端点，即可监控应用的运行状况。

测试1：/health端点

为前文编写的microservice-simple-provider-user 服务整合Actuator后，我们来做一些测试：

访问<http://localhost:8000/actuator/health> ，即可获得如下结果：

{"status":"UP"}

测试2：/health端点展示详情

为/health 端点配置显示详情：

management:
  endpoint:
    health:
      # 是否展示健康检查详情
      show-details: always

再次访问<http://localhost:8000/actuator/health> ，即可获得如下结果：

{
    "status": "UP",
    "details": {
        "db": {
            "status": "UP",
            "details": {
                "database": "H2",
                "hello": 1
            }
        },
        "diskSpace": {
            "status": "UP",
            "details": {
                "total": 250790436864,
                "free": 43443773440,
                "threshold": 10485760
            }
        }
    }
}

从中可以看到，/health 端点展示了DB的健康情况以及磁盘的健康情况。

测试3：暴露敏感路径

默认情况下，敏感路径并不暴露。如需暴露（以metrics为例），需添加配置：

management:
  endpoints:
    web:
      exposure:
        # 暴露metrics端点，如需暴露多个，用,分隔；如需暴露所有端点，用'*'
        include: metrics

访问：<http://localhost:8000/actuator/metrics> ，可获得类似如下的结果：

{
    "names": ["jvm.memory.max", "http.server.requests", "jdbc.connections.active", "process.files.max", "jvm.gc.memory.promoted", "tomcat.cache.hit", "system.load.average.1m", "tomcat.cache.access", "jvm.memory.used", "jvm.gc.max.data.size", "jdbc.connections.max", "jdbc.connections.min", "jvm.gc.pause", "jvm.memory.committed", "system.cpu.count", "logback.events", "tomcat.global.sent", "jvm.buffer.memory.used", "tomcat.sessions.created", "jvm.threads.daemon", "system.cpu.usage", "jvm.gc.memory.allocated", "tomcat.global.request.max", "hikaricp.connections.idle", "hikaricp.connections.pending", "tomcat.global.request", "tomcat.sessions.expired", "hikaricp.connections", "jvm.threads.live", "jvm.threads.peak", "tomcat.global.received", "hikaricp.connections.active", "hikaricp.connections.creation", "process.uptime", "tomcat.sessions.rejected", "process.cpu.usage", "tomcat.threads.config.max", "jvm.classes.loaded", "hikaricp.connections.max", "hikaricp.connections.min", "jvm.classes.unloaded", "tomcat.global.error", "tomcat.sessions.active.current", "tomcat.sessions.alive.max", "jvm.gc.live.data.size", "tomcat.servlet.request.max", "hikaricp.connections.usage", "tomcat.threads.current", "tomcat.servlet.request", "hikaricp.connections.timeout", "process.files.open", "jvm.buffer.count", "jvm.buffer.total.capacity", "tomcat.sessions.active.max", "hikaricp.connections.acquire", "tomcat.threads.busy", "process.start.time", "tomcat.servlet.error"]
}

访问http://localhost:8000/actuator/metrics/{name} ，{name} 列表如上，即可查看当前应用的度量指标。例如访问：<http://localhost:8000/actuator/metrics/jvm.memory.max> 即可查看JVM可管理的最大内存，结果类似如下：

{
    "name": "jvm.memory.max",
    "description": "The maximum amount of memory in bytes that can be used for memory management",
    "baseUnit": "bytes",
    "measurements": [{
        "statistic": "VALUE",
        "value": 5.597298687E9
    }],
    "availableTags": [{
        "tag": "area",
        "values": ["heap", "nonheap"]
    }, {
        "tag": "id",
        "values": ["Compressed Class Space", "PS Survivor Space", "PS Old Gen", "Metaspace", "PS Eden Space", "Code Cache"]
    }]
}

TIPS

• 如需暴露所有监控端点可配置：

  management:
  endpoints:
    web:
      exposure:
        include: '*'

• 有关Spring Boot 1.x与2.x端点的差异，详见：<https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.0-Migration-Guide#endpoints>

拓展阅读

如果能对Actuator端点的文字数据进行图形化的展示，我们就可以实现比较低层次的“Growth Hack”啦！开源界已经有这样的工具——Spring Boot Admin ，界面如下。有兴趣的可前往<https://github.com/codecentric/spring-boot-admin>了解。

说明

• 由于Actuator本身是Spring Boot中的组件，并不是本套教程的重点（其实笔者本不想写这一节，但后面又会持续用这些端点，并且Spring Cloud在这些端点的基础上还做了一些增加，所以还是有必要介绍一下），因此本节只是对Actuator进行了比较简单的介绍，读者可自行挖掘Actuator的其他能力。也可持续关注本公众号，本系列完成后，笔者将会扒开Actuator的底裤，深度介绍Spring Boot监控的那些事儿。

配套代码

GitHub：

• https://github.com/eacdy/spring-cloud-study/tree/master/2018-Finchley/microservice-simple-provider-user
• https://github.com/eacdy/spring-cloud-study/tree/master/2018-Finchley/microservice-simple-consumer-movie

Gitee：

• https://gitee.com/itmuch/spring-cloud-study/tree/master/2018-Finchley/microservice-simple-provider-user
• https://gitee.com/itmuch/spring-cloud-study/tree/master/2018-Finchley/microservice-simple-consumer-movie

原文：http://www.itmuch.com/spring-cloud/finchley-3/ ，转载请说明出处。

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