micrometer自定义metrics

micrometer提供了基于Java的monitor facade，其与springboot应用和prometheus的集成方式如下图展示

上图中展示的很清楚，应用通过micrometer采集和暴露监控端点给prometheus，prometheus通过pull模式来采集监控时序数据信息。之后作为数据源提供给grafana进行展示。

micrometer支持的度量方式及在springboot中的应用示例

Counter
Counter(计数器)简单理解就是一种只增不减的计数器。它通常用于记录服务的请求数量、完成的任务数量、错误的发生数量等等。

package com.dxz.producter.monitor;

import org.springframework.stereotype.Service;

import io.micrometer.core.instrument.Counter;
import io.micrometer.core.instrument.Metrics;

@Service("collectorService")
public class CollectorService {

    static final Counter userCounter = Metrics.counter("user.counter.total", "services", "demo");

    public void processCollectResult() throws InterruptedException {

        while (true) {
            userCounter.increment(1D);
        }
    }
}

Gauge
Gauge(仪表)是一个表示单个数值的度量，它可以表示任意地上下移动的数值测量。Gauge通常用于变动的测量值，如当前的内存使用情况，同时也可以测量上下移动的"计数"，比如队列中的消息数量。

package com.dxz.producter.monitor;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

import org.springframework.stereotype.Component;

import io.micrometer.core.instrument.Gauge;
import io.micrometer.core.instrument.ImmutableTag;
import io.micrometer.core.instrument.Metrics;
import io.micrometer.core.instrument.Tag;
import io.micrometer.core.instrument.simple.SimpleMeterRegistry;

@Component("passCaseMetric")
public class PassCaseMetric {

    List<Tag> init() {
        ArrayList<Tag> list = new ArrayList() {
        };
        list.add(new ImmutableTag("service", "demo"));
        return list;
    }

    AtomicInteger atomicInteger = new AtomicInteger(0);

    Gauge passCaseGuage = Gauge.builder("pass.cases.guage", atomicInteger, AtomicInteger::get).tag("service", "demo")
            .description("pass cases guage of demo").register(new SimpleMeterRegistry());

    AtomicInteger passCases = Metrics.gauge("pass.cases.guage.value", init(), atomicInteger);

    public void handleMetrics() {

        while (true) {
            if (System.currentTimeMillis() % 2 == 0) {
                passCases.addAndGet(100);
                System.out.println("ADD + " + passCaseGuage.measure() + " : " + passCases);
            } else {
                int val = passCases.addAndGet(-100);
                if (val < 0) {
                    passCases.set(1);
                }
                System.out.println("DECR - " + passCaseGuage.measure() + " : " + passCases);
            }
        }

    }

}

增加一个controller，触发他们：

package com.dxz.producter.web;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.dxz.producter.monitor.CollectorService;
import com.dxz.producter.monitor.PassCaseMetric;

@RestController
@RequestMapping("/monitor")
public class MonitorController {

    @Autowired
    CollectorService collectorService;
    
    @Autowired
    PassCaseMetric passCaseMetric;
    
    @RequestMapping(value = "/counter", method = RequestMethod.GET)
    public String counter() throws InterruptedException {
        collectorService.processCollectResult();
        return "+1";
    }
    
    @RequestMapping(value = "/gauge", method = RequestMethod.GET)
    public String gauge() throws InterruptedException {
        passCaseMetric.handleMetrics();
        return "+gauge";
    }
    
}

启动springboot应用，可以在http://host:port/actuator/prometheus 看到端点收集到的数据。其他的也是类似的不再一一截图展示。

这里使用了一个true的循环用来展示不断更新的效果。

同样的可以在grafana中看到监控展示信息

Timer
Timer(计时器)同时测量一个特定的代码逻辑块的调用(执行)速度和它的时间分布。简单来说，就是在调用结束的时间点记录整个调用块执行的总时间，适用于测量短时间执行的事件的耗时分布，例如消息队列消息的消费速率。

@Test
    public void testTimerSample(){
        Timer timer = Timer.builder("timer")
                .tag("timer", "timersample")
                .description("timer sample test.")
                .register(new SimpleMeterRegistry());
 
        for(int i=0; i<2; i++) {
            timer.record(() -> {
                try {
                    TimeUnit.SECONDS.sleep(2);
                }catch (InterruptedException e){
 
                }
 
            });
        }
 
        System.out.println(timer.count());
        System.out.println(timer.measure());
        System.out.println(timer.totalTime(TimeUnit.SECONDS));
        System.out.println(timer.mean(TimeUnit.SECONDS));
        System.out.println(timer.max(TimeUnit.SECONDS));
    }

响应数据

2
[Measurement{statistic='COUNT', value=2.0}, Measurement{statistic='TOTAL_TIME', value=4.005095763}, Measurement{statistic='MAX', value=2.004500494}]
4.005095763
2.0025478815
2.004500494

Summary
Summary(摘要)用于跟踪事件的分布。它类似于一个计时器，但更一般的情况是，它的大小并不一定是一段时间的测量值。在micrometer中，对应的类是DistributionSummary，它的用法有点像Timer，但是记录的值是需要直接指定，而不是通过测量一个任务的执行时间。

@Test
    public void testSummary(){
 
        DistributionSummary summary = DistributionSummary.builder("summary")
                .tag("summary", "summarySample")
                .description("summary sample test")
                .register(new SimpleMeterRegistry());
 
        summary.record(2D);
        summary.record(3D);
        summary.record(4D);
 
        System.out.println(summary.count());
        System.out.println(summary.measure());
        System.out.println(summary.max());
        System.out.println(summary.mean());
        System.out.println(summary.totalAmount());
    }

响应数据：

3
[Measurement{statistic='COUNT', value=3.0}, Measurement{statistic='TOTAL', value=9.0}, Measurement{statistic='MAX', value=4.0}]
4.0
3.0
9.0

序

本文主要研究下如何使用自定义micrometer的metrics

实例

DemoMetrics

public class DemoMetrics implements MeterBinder {
    AtomicInteger count = new AtomicInteger(0);

    @Override
    public void bindTo(MeterRegistry meterRegistry) {
        Gauge.builder("demo.count", count, c -> c.incrementAndGet())
                .tags("host", "localhost")
                .description("demo of custom meter binder")
                .register(meterRegistry);
    }
}

这里实现了MeterBinder接口的bindTo方法，将要采集的指标注册到MeterRegistry

注册

• 原始方式

new DemoMetrics().bindTo(registry);

• springboot autoconfigure

@Bean
public DemoMetrics demoMetrics(){
    return new DemoMetrics();
}

在springboot只要标注下bean，注入到spring容器后，springboot会自动注册到registry。springboot已经帮你初始化了包括UptimeMetrics等一系列metrics。详见源码解析部分。

验证

curl -i http://localhost:8080/actuator/metrics/demo.count

返回实例

{
  "name": "demo.count",
  "measurements": [
    {
      "statistic": "VALUE",
      "value": 6
    }
  ],
  "availableTags": [
    {
      "tag": "host",
      "values": [
        "localhost"
      ]
    }
  ]
}

源码解析

MetricsAutoConfiguration

spring-boot-actuator-autoconfigure-2.0.0.RELEASE-sources.jar!/org/springframework/boot/actuate/autoconfigure/metrics/MetricsAutoConfiguration.java

@Configuration
@ConditionalOnClass(Timed.class)
@EnableConfigurationProperties(MetricsProperties.class)
@AutoConfigureBefore(CompositeMeterRegistryAutoConfiguration.class)
public class MetricsAutoConfiguration {

    @Bean
    @ConditionalOnMissingBean
    public Clock micrometerClock() {
        return Clock.SYSTEM;
    }

    @Bean
    public static MeterRegistryPostProcessor meterRegistryPostProcessor(
            ApplicationContext context) {
        return new MeterRegistryPostProcessor(context);
    }

    @Bean
    @Order(0)
    public PropertiesMeterFilter propertiesMeterFilter(MetricsProperties properties) {
        return new PropertiesMeterFilter(properties);
    }

    @Configuration
    @ConditionalOnProperty(value = "management.metrics.binders.jvm.enabled", matchIfMissing = true)
    static class JvmMeterBindersConfiguration {

        @Bean
        @ConditionalOnMissingBean
        public JvmGcMetrics jvmGcMetrics() {
            return new JvmGcMetrics();
        }

        @Bean
        @ConditionalOnMissingBean
        public JvmMemoryMetrics jvmMemoryMetrics() {
            return new JvmMemoryMetrics();
        }

        @Bean
        @ConditionalOnMissingBean
        public JvmThreadMetrics jvmThreadMetrics() {
            return new JvmThreadMetrics();
        }

        @Bean
        @ConditionalOnMissingBean
        public ClassLoaderMetrics classLoaderMetrics() {
            return new ClassLoaderMetrics();
        }

    }

    @Configuration
    static class MeterBindersConfiguration {

        @Bean
        @ConditionalOnClass(name = { "ch.qos.logback.classic.LoggerContext",
                "org.slf4j.LoggerFactory" })
        @Conditional(LogbackLoggingCondition.class)
        @ConditionalOnMissingBean(LogbackMetrics.class)
        @ConditionalOnProperty(value = "management.metrics.binders.logback.enabled", matchIfMissing = true)
        public LogbackMetrics logbackMetrics() {
            return new LogbackMetrics();
        }

        @Bean
        @ConditionalOnProperty(value = "management.metrics.binders.uptime.enabled", matchIfMissing = true)
        @ConditionalOnMissingBean
        public UptimeMetrics uptimeMetrics() {
            return new UptimeMetrics();
        }

        @Bean
        @ConditionalOnProperty(value = "management.metrics.binders.processor.enabled", matchIfMissing = true)
        @ConditionalOnMissingBean
        public ProcessorMetrics processorMetrics() {
            return new ProcessorMetrics();
        }

        @Bean
        @ConditionalOnProperty(name = "management.metrics.binders.files.enabled", matchIfMissing = true)
        @ConditionalOnMissingBean
        public FileDescriptorMetrics fileDescriptorMetrics() {
            return new FileDescriptorMetrics();
        }

    }

    static class LogbackLoggingCondition extends SpringBootCondition {

        @Override
        public ConditionOutcome getMatchOutcome(ConditionContext context,
                AnnotatedTypeMetadata metadata) {
            ILoggerFactory loggerFactory = LoggerFactory.getILoggerFactory();
            ConditionMessage.Builder message = ConditionMessage
                    .forCondition("LogbackLoggingCondition");
            if (loggerFactory instanceof LoggerContext) {
                return ConditionOutcome.match(
                        message.because("ILoggerFactory is a Logback LoggerContext"));
            }
            return ConditionOutcome
                    .noMatch(message.because("ILoggerFactory is an instance of "
                            + loggerFactory.getClass().getCanonicalName()));
        }

    }

}

可以看到这里注册了好多metrics，比如UptimeMetrics，JvmGcMetrics，ProcessorMetrics，FileDescriptorMetrics等

这里重点看使用@Bean标注了MeterRegistryPostProcessor

MeterRegistryPostProcessor

spring-boot-actuator-autoconfigure-2.0.0.RELEASE-sources.jar!/org/springframework/boot/actuate/autoconfigure/metrics/MeterRegistryPostProcessor.java

class MeterRegistryPostProcessor implements BeanPostProcessor {

    private final ApplicationContext context;

    private volatile MeterRegistryConfigurer configurer;

    MeterRegistryPostProcessor(ApplicationContext context) {
        this.context = context;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName)
            throws BeansException {
        if (bean instanceof MeterRegistry) {
            getConfigurer().configure((MeterRegistry) bean);
        }
        return bean;
    }

    @SuppressWarnings("unchecked")
    private MeterRegistryConfigurer getConfigurer() {
        if (this.configurer == null) {
            this.configurer = new MeterRegistryConfigurer(beansOfType(MeterBinder.class),
                    beansOfType(MeterFilter.class),
                    (Collection<MeterRegistryCustomizer<?>>) (Object) beansOfType(
                            MeterRegistryCustomizer.class),
                    this.context.getBean(MetricsProperties.class).isUseGlobalRegistry());
        }
        return this.configurer;
    }

    private <T> Collection<T> beansOfType(Class<T> type) {
        return this.context.getBeansOfType(type).values();
    }

}

可以看到这里new了一个MeterRegistryConfigurer，重点注意这里使用beansOfType(MeterBinder.class)方法的返回值给其构造器

MeterRegistryConfigurer

spring-boot-actuator-autoconfigure-2.0.0.RELEASE-sources.jar!/org/springframework/boot/actuate/autoconfigure/metrics/MeterRegistryConfigurer.java

class MeterRegistryConfigurer {

    private final Collection<MeterRegistryCustomizer<?>> customizers;

    private final Collection<MeterFilter> filters;

    private final Collection<MeterBinder> binders;

    private final boolean addToGlobalRegistry;

    MeterRegistryConfigurer(Collection<MeterBinder> binders,
            Collection<MeterFilter> filters,
            Collection<MeterRegistryCustomizer<?>> customizers,
            boolean addToGlobalRegistry) {
        this.binders = (binders != null ? binders : Collections.emptyList());
        this.filters = (filters != null ? filters : Collections.emptyList());
        this.customizers = (customizers != null ? customizers : Collections.emptyList());
        this.addToGlobalRegistry = addToGlobalRegistry;
    }

    void configure(MeterRegistry registry) {
        if (registry instanceof CompositeMeterRegistry) {
            return;
        }
        // Customizers must be applied before binders, as they may add custom
        // tags or alter timer or summary configuration.
        customize(registry);
        addFilters(registry);
        addBinders(registry);
        if (this.addToGlobalRegistry && registry != Metrics.globalRegistry) {
            Metrics.addRegistry(registry);
        }
    }

    @SuppressWarnings("unchecked")
    private void customize(MeterRegistry registry) {
        LambdaSafe.callbacks(MeterRegistryCustomizer.class, this.customizers, registry)
                .withLogger(MeterRegistryConfigurer.class)
                .invoke((customizer) -> customizer.customize(registry));
    }

    private void addFilters(MeterRegistry registry) {
        this.filters.forEach(registry.config()::meterFilter);
    }

    private void addBinders(MeterRegistry registry) {
        this.binders.forEach((binder) -> binder.bindTo(registry));
    }

}

可以看到configure方法里头调用了addBinders，也就是把托管给spring容器的MeterBinder实例bindTo到meterRegistry

小结

springboot2引入的micrometer，自定义metrics只需要实现MeterBinder接口，然后托管给spring即可，springboot的autoconfigure帮你自动注册到meterRegistry。