引语

SpringBoot升级到2.0后，重构了很大一部分代码，导致原官方提供SpringBoot-Starter不再适用，可以用io.micrometer:micrometer-registry-prometheus配合spring-boot-starter-actuator适用，笔者通过实践验证可以实现，但发现采集的指标过多，包括JVM等监控指标，笔者只想暴露自己自定义的一种指标，未搜索到可以关闭部分指标的配置，于是准备从源码入手完成实现

参考官方实现，基于SpringBoot Actuator，给出一种简单的实现思路，直接贴出代码

依赖项【笔者基于Gradle，Maven类似】：

buildscript {
    ext["springBootVersion"] = "2.2.7.RELEASE"
}
// 依赖版本管理
dependencyManagement {
        dependencies {
            imports {
                mavenBom "org.springframework.boot:spring-boot-dependencies:${springBootVersion}"
            }

            dependency "io.prometheus:simpleclient:0.8.1"
        }
    }
}

// 添加依赖
compile "org.springframework.boot:spring-boot-starter-actuator"
compile 'io.prometheus:simpleclient'

自定义类一：

@WebEndpoint(id = "prometheus")
public class MyPrometheusEndpoint {
    private final CollectorRegistry collectorRegistry;

    public MyPrometheusEndpoint(CollectorRegistry collectorRegistry) {
        this.collectorRegistry = collectorRegistry;
    }

    @ReadOperation(produces = TextFormat.CONTENT_TYPE_004)
    public String scrape() {
        try {
            Writer writer = new StringWriter();
            TextFormat.write004(writer, this.collectorRegistry.metricFamilySamples());
            return writer.toString();
        } catch (IOException ex) {
            // This actually never happens since StringWriter::write() doesn't throw any
            // IOException
            throw new RuntimeException("Writing metrics failed", ex);
        }
    }
}

自定义类二：

@Configuration
public class MyPrometheusMetricsExportAutoConfiguration {

    public static final CollectorRegistry collectorRegistry = new CollectorRegistry();

    @Bean
    public MyPrometheusEndpoint myPrometheusEndpoint() {
        return new MyPrometheusEndpoint(collectorRegistry);
    }

}

自定义类三【指标搜集类，自定义Collector】：

@Component
@Slf4j
public class MonitorCheckExporter extends Collector {

    @Override
    public List<MetricFamilySamples> collect() {
        List<MetricFamilySamples> mfs = new ArrayList<>();

        /*
        * 指标采集逻辑
        * */

        return mfs;
    }

}

SpringBoot启动类：

public class Application implements CommandLineRunner {

    @Resource
    private MonitorCheckExporter monitorCheckExporter;

    public static void main(String[] args) {
        SpringApplication sa = new SpringApplication(Application.class);
        sa.run(args);
    }

    @Override
    public void run(String... args) throws Exception {
        monitorCheckExporter.register(MyPrometheusMetricsExportAutoConfiguration.collectorRegistry);
    }
}

至此，可实现SpringBoot2.0暴露/actuator/prometheus接口供prometheus拉取自定义指标的功能

Prometheus自定义Exporter在SpringBoot2.0的实践

引语